The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: bikerboy on 12.09. 2019 00:49
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This is a long story and it is in relation to my recently rebuilt A10 plunger frame. Not that it makes any difference but its got a large journal crank, thick flange barrels and an alloy head (A10 not A7)
I finished it a couple of months ago, regrind new shells, new bearing and bushes line bored etc etc guides valves all new the only thing not new was the pistons and rings they seemed ok and the bore measured ok, not great but ok.
Took it out done 28 miles and noticed a significant loss out of the engine breather once it got hot, I know some hate them but I fitted a wet sumping valve as it was wet sumping despite new check valve ball and spring. Unfortunately it also went on to one cylinder as something got dragged into the carb (no air filter as always)
Took the top end off again no big damage but as it was losing oil out of the breather decided on a rebore and new pistons as they were the only thing it could be. Flat top pistons not some 10:1 job.
Now the confusion starts. Started it no problem and oil circulated and pumped out of the breather at the same rate it came back to the tank. No smoke and it stopped after a few minutes so I assumed some oil had crept down to the sump despite the valve. Done 5 miles and everything cool, oil pumping round well and running fine so off I went, no sign of any more loss from the breather.
18 miles later most of the bike covered in oil and oil tank nearly empty. Was at a friends so topped up the oil and investigated. Circulating intermittently almost like a restriction in the line. Rocker feed even tho it was jubilee clipped blew the pipe off and oil pumping out at a rapid rate. Has to be a blockage in the oil tank I assumed. Tank off pipes cleaned even poked an old throttle cable down the tank from the top in case crap was in the tank return pipe. Nothing all perfectly clean and clear. Then fitted a replacement return pipe into a separate container so that I could watch the return easily.
Start it up again oil circulating nicely and again pumping out of the breather at the same rate that it is circulating. Assumed I must have broken a piston ring when fitting new pistons so compression test, all proved fine, still no sign of any smoke, spark plugs a perfect colour engine starts and runs fine.
After running for a few minutes, oil stops from breather and everything is perfect.
What the hell will cause oil to spew out at a ridiculous rate intermittently from the engine breather yet still circulate and run fine? Not only when its cold and has not been used even when it is hot and being ridden.
Pump has been tried and tested on my other A10 I only changed it to give me a tacho drive on my Super Rocket.
Oil straight 40 not that it matters.
Obviously all oilways checked and blown out during rebuild. I do not have one of the drain plug sumps with a magnet on it.
So no smoke at all, perfect starting and revving, plugs a perfect colour. I really am confused and baffled. I cant see why it would be the PRV which does have a new ball and spring anyway.
My next move is to remove the sump and leave a container under it to see if the sump is filling with oil but the tank level is not dropping, well not until it throws all the oil out of the breather its not. Anyway it cant wet sump when its being held at 50 mph for 10 miles surely?
Any suggestions would prove very well received :(
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Are you sure the oil is coming out the breather hole?
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Positive its pipe on this plunger of mine
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Just a thought, is the vent in your oil tank working?
Blowing lines off, oil out of the breather, i can only think that pressure is building up and looking for an escape route.
Lee
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Just a thought, is the vent in your oil tank working?
Blowing lines off, oil out of the breather, i can only think that pressure is building up and looking for an escape route.
Poking a wire up the tank vent would sort that, but taking the tank filler cap off and blowing in it will also give an indication.....or both in conjunction (saves any crap ending up in the tank)
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The breather is timed, are you shure the plug from the camshaftpinion is always in its hole?
Its only a suggestion, as you wrote, sometimes its all ok.
cheers Klaus
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Looks like too much oil added, and the scavenge side of the system with an intermittent fault. I would suspect an air leak or blockage in the sump pick up pipe...the welded 90 degree bend where it enters the crankcase behind the pump sometimes fractures, crack opens as motor warms up, pump sucks air instead of oil. The ball valve on the end of the pipe also needs a looky look....The ball movement on some pipes is almost zilch, restricted with a build up of carbon and other muck. The construction of this neglected component is detailed somewhere on the Forum.
As a start, begin with the basics, tank, pipes, tank breather all clear, timed breather set up with no play, with a well sealing cork washer. With the inner cover off, check timing gears are correctly indexed and the correct ones.....Longstroke gears look the same, but timing marks slightly different, but unlikely on a motor which runs OK otherwise. Oil pump... securing nuts tight, good gasket in place, no holes blocked, anti drain ball valve behind pump still in place. Check operation by pushing a matchstick down the oilway and feel for a spring loaded ball. Sump plate off, sump drained "dry", plate back on and oil tank filled with correct quantity of oil. Start 'er up, oil should return as small gulps, changing to a good steady stream after a few moments running. If the problem remains, the pick up pipe is number one suspect, followed by the pump. This all assumes the delivery side is working OK, but here an internal leak will overwhelm even a correctly working scavenge side.
Look for a post "Oil suddenly coming out of the breather" what has happened is fairly common.
Swarfy.
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G'day bb.
I'm thinking the scavenge pipe is the problem. As Swarfy mentioned the pipe can fracture or the ball restricts flow. The pump draws oil from the tank so oil is being deposited into the sump. The scavenge side of the pump is getting some but not all of it out till the level in the sump covers the fracture and starts scavenging normally. By this time oil is spewing out the breather.
Klaus has a good point about the timed breather. Double check it and the cork is a good size (10 to 20 thou crush).
As for blowing off the rocker feed. *dunno* clamp not tight. Do you have a filter on the return line after the rocker feed tee off but before the tank?
Cheers
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Hi,
Swarfy covered almost everything there
1 more , is there a magnetic drain plug in the sump plate? This can cause the ball to stick.
Also there's a pin or clip to prevent the ball being sucked up to the narrower part of the tube, If missing the ball will block the oil
John
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Hi,
Swarfy covered almost everything there
1 more , is there a magnetic drain plug in the sump plate? This can cause the ball to stick.
Also there's a pin or clip to prevent the ball being sucked up to the narrower part of the tube, If missing the ball will block the oil
John
"I do not have one of the drain plug sumps with a magnet on it."
He does NOT have a magnet in the sump,
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Thanks for all your comments and help just to answer a few questions.
The cork washer on the end of the camshaft is fine and the breather peg is located.
It has no oil filter fitted, the return pipe has a simple T piece in that goes off to the rocker box just before it enters the tank. I think the rocker pipe blew off when I put my finger over the return hole hoping to encourage the oil to circulate.
I have, in my own mind, put the problem purely down to the return system to the tank but I must admit it never occurred to me that the scavenge pipe could be cracked and if it is then that would explain everything. Sticky ball yes but I never thought about a crack.
With the plunger if my memory serves me rightly the scavenge pipe is actually bolted to the inside of the crankcase, I will have to hook out another set of cases and check. If it is then its an engine strip down for sure :(
Now correct me if I am wrong but if its not just the ball sticking, which I doubt I am quite thorough on a rebuild as a rule. That pipe returns directly to the back of the oil pump so removing the pump and putting an air line on it should expose a crack particularly if I wobble the pipe a bit as I blast air into it.
Looks like it could be another weekend spent on stripping and rebuilding again :(
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Yes, the pick up pipe is bolted to the crankcase at its lower end, bolt secured with a tab washer. BSA recommended never to disturb the pipe, as back in the day it was "cemented" into the crankcase, probably with the 1950's forerunner of Loctite Bearing Fit, which should do the job today. If it's loose and wobbles, not sealed to the crankcase, could be the problem. So, a finger over the oilway behind the pump and a plastic tube over the business end and a little bit of air pressure should locate a crack in the pipe, poor seal between pipe and crankcase or a dodgy bit of welding or brazing in the construction of the pick up pipe. If all OK, check for a sticking ball...not moving enough, or the retainer in the ball housing compromised and drawing the ball up to block the pipe, as mentioned by Chaterlea John. If it all seems in order, then the mystery continues, so although it could mean a major strip, cross fingers for some sign of an answer.
The design is different on S/A motors....a straight pick up pipe and internal oilways drilled in the alloy crankcase. Any chance one of the big end bolts on the big journal crank has caught and flattened the pipe, or even machined a hole in it?
Swarfy.
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G'day Swarfy.
That's a good point. I didn't consider the LJ crank touching the pipe.
When I put a LJ crank into the A7SS cases I had to remove a bit off the nuts to give clearance as they hit the case. Also had to deepen the cam trough for the 357 cam.
Cheers
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Thanks for all your comments and help just to answer a few questions.
The cork washer on the end of the camshaft is fine and the breather peg is located.
It has no oil filter fitted, the return pipe has a simple T piece in that goes off to the rocker box just before it enters the tank. I think the rocker pipe blew off when I put my finger over the return hole hoping to encourage the oil to circulate.
I have, in my own mind, put the problem purely down to the return system to the tank but I must admit it never occurred to me that the scavenge pipe could be cracked and if it is then that would explain everything. Sticky ball yes but I never thought about a crack.
With the plunger if my memory serves me rightly the scavenge pipe is actually bolted to the inside of the crankcase, I will have to hook out another set of cases and check. If it is then its an engine strip down for sure :(
Now correct me if I am wrong but if its not just the ball sticking, which I doubt I am quite thorough on a rebuild as a rule. That pipe returns directly to the back of the oil pump so removing the pump and putting an air line on it should expose a crack particularly if I wobble the pipe a bit as I blast air into it.
Looks like it could be another weekend spent on stripping and rebuilding again :(
I’ve heard of s/a bikes where the scavenge pipe had fallen off (or was missing) without causing symptoms of wet sumping, as the oil level just rises a bit to the level of the gallery in the case, I’m not sure if this is the case with the semi unit engines but I thought it worth mentioning, before you strip it down!
It does sound like the cases are filling with oil.
I had a puzzling oil supply issue with a Honda gb500 (no supply to head/cam), I eventually worked out what was going wrong by “experimenting” with pieces of tube and bottles to hold supply/return oil, this may be an option for you before you strip it down *dunno*
Edit...I just re read yr 1st post and oil was coming out of the head oil feed “fast” when you had the oil coming out the breather, no way it should ever be “fast” ....the oil supply to the valves on my bike is a dribble at best. That indicates the cause is probably a blockage (intermittent?) between the tee to the head and the hole in the tank pipe doesn’t it?
I think Rocket Racer had this issue (during a rally) and the blockage was cleared quite easily.
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Thanks for your ideas lads regarding the crank but I have run an LJ in plunger cases for years and feel sure I would have noticed anything like that but I will check it of course.
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BB...Here's me thinking you know nothing about these motors... turns out you are well experienced and with what looks like a choice when it comes to replacement parts. Apologies if I have stated the obvious, but it is always difficult to know what knowledge, experience and skills the fella with the problem has. Looks as if despite your engine building skill, it has defeated you (and a good few others) for the time being.
Stick with the KiWi....a re visit of the oil lines and tank is quick and easy.....a good pressure on the return side of the pump would indicate reasonable pick up and a good pump.
KiWi....Working OK without the pipe is possible on the S/A engine, the oilway is just above sump plate level. The plunger pipe works its way from the sump, hugging the inner crankcase wall, so the oil would need to be up to the main bearing bush, and higher, by which time all the oil is out of the tank and being spread over the road.
Swarfy.
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Swarfy
No problem got my first A10 (and still got it) back in 1972 when I was 16 and have had so many to bits over the years I have lost count :)
But as you know that does not mean somebody has all the answers nor does it mean that sometimes we overlook the obvious so I am always grateful for advice particularly as some people on this forum make me look like a total newbie with their technical knowledge.
I would still pit myself against anybody at fitting the rocker box tho, I definitely have that down to a fine art and can fit one in minutes :)
Probably because of the amount of times I have messed up a rebuild and needed to have the rocker box on and off 150 times lol
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“”I would still pit myself against anybody at fitting the rocker box tho, I definitely have that down to a fine art and can fit one in minutes””
If you fancy posting some tips on this subject, or a “how to” video, I would not be offended!!!
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Hi Minto, If I were to pay your fare to Adelaide Australia plus accomodation and meals due you think you would be able to fit my rocker box on my 59 A10......:-) Cheers Gerry
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Hey Gerry
That sounds great, I’ll pack my case later. I’ll see if I can talk BikerBoy into coming as well, he can show us both how it’s done. 👍😁
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I had the same problem turned out to be the pressure release valve makes no sence but changed it and hey presto
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Of all the different engines I've worked on in the last 55 + years, from lawnmowers to race cars plus marine, I've never come across an engine model with more oil issues (most of which are plain weird) than the A series. The singles use a similar system without problems, so why are the twins less reliable lubrication-wise than the weather? And let's not pretend that isn't the case, as the posts on this forum prove otherwise.
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Of all the different engines I've worked on in the last 55 + years, from lawnmowers to race cars plus marine, I've never come across an engine model with more oil issues (most of which are plain weird) than the A series. The singles use a similar system without problems, so why are the twins less reliable lubrication-wise than the weather? And let's not pretend that isn't the case, as the posts on this forum prove otherwise.
I recon you can point the finger directly at the R/H main bush with oil trying to be forced through a rotating shaft with a small hole drilled in it. Most other reliable systems have a centre fed crank. Once the crank starts spinning it acts like a centrifugal pump in itself. maybe if BSA had fitted a pump with twice the volume it may have worked properly (eg auto crank & pump style). Other engines with Right hand main bush oil systems suffer as well, one that comes to mind are the AMC singles. ( try finding one without a shot bigend bearing). the difference between these & BSA singles are chalk & cheese, yet they both use roller bearings, in fact at a quick glance the AMC looks beefier.
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Minto
I can give you one tip I sometimes use
Bend the pushrod comb so that it comes down to sit on the top fin of the cylinder head. Use one of those spring steel chassis clips to slide over the fin and the comb holding it nicely in place. Make sure its one of the inlet pushrods that is high so the two exhaust rods are at at the same height.
Loosen the adjuster nuts on the tappets but do not slacken the actually tappets at all. Slip the box on and all those little rods will drop straight into those cups perfectly every time
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Well so far no joy. Oil pipes off and all clear, return to the tank clear as a bell.
Sump off and there was too much oil in there but as the pump is tried and tested a bit confused as to why.
Scavenge pipe not blocked in any way (no magnetic bolt on it)
The only parts on this bike I have not run relatively recently are the crankcases so to me I am still thinking scavenge pipe but god knows why.
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As an indication of the oil return, try a transparent plastic pipe fitted onto the scavenge pipe dipped into oil in an oil drain pan under the open sump. A bit messy, but shows the relative balance between feed and return. Poor pick up is a combination of obstruction, air leaks, poor seal between pump and crankcase, or just a poorly performing pump.
Here look for a worn, cracked body, sheared off drive tab on scavenge gear, really badly worn or loose end plate. Not all or any may apply to your pump. Long shot, but substituting another pump would be well worth another try before a full strip down to change the cases.
The PRV is an enigma, as open or shut the total volume of oil delivered is the same, whether blown off or fed under pressure to the crank bush and bearings. But experience would indicate changing the PRV can sometimes effect a cure for mysterious oil problems.
Swarfy.
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On Tr*umph twins it's possible to test the scavenge pipe by slipping a piece of tubing over the scavenge pipe and gently sucking while blocking the oilway on the engine with your thumb.
It's a good definitive test of the pipe, so maybe it could be used here too?
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Well I have changed everything except the PRV which looks fine.
Oil circulates perfectly but its still throwing it out of the breather when it does more than about 15 miles :(
Looks like another strip down after swapping the PRV with one of my working A10's which I dont think will cure it :(
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i would say the prv is very important and worth a good examine of the ball and seat. if the ball doesnt seat after the oil warms [ spring ] oil will be dumped into your crankcase and out the breather. it will ruin your big ends quickly as they lose oil pressure.
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I once found a nasty split in a BSA prv where the ball seats. I was looking to use one on the beezer until I thought sod it your messing with the engines heart and bought srm pump and prv. I had a few and even converted one when I wanted to play about with something to test oil pressure before and after relief to cam etc. The springs and seat can never be as good as when they left the factory I couldn't believe a hard ball bearing could have such a wear mark in it but then again its getting attacked by all sorts of impurities *bash*, after all i'me bu**ered at 60 *sleepy* and some of them are even older than me, the pump and prv should be pensioned off unless put to a test and proven to be able to provide a good service *warn*
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Thanks for all your comments and help just to answer a few questions.
The cork washer on the end of the camshaft is fine and the breather peg is located.
It has no oil filter fitted, the return pipe has a simple T piece in that goes off to the rocker box just before it enters the tank. I think the rocker pipe blew off when I put my finger over the return hole hoping to encourage the oil to circulate.
I have, in my own mind, put the problem purely down to the return system to the tank but I must admit it never occurred to me that the scavenge pipe could be cracked and if it is then that would explain everything. Sticky ball yes but I never thought about a crack.
With the plunger if my memory serves me rightly the scavenge pipe is actually bolted to the inside of the crankcase, I will have to hook out another set of cases and check. If it is then its an engine strip down for sure :(
Now correct me if I am wrong but if its not just the ball sticking, which I doubt I am quite thorough on a rebuild as a rule. That pipe returns directly to the back of the oil pump so removing the pump and putting an air line on it should expose a crack particularly if I wobble the pipe a bit as I blast air into it.
Looks like it could be another weekend spent on stripping and rebuilding again :(
I’ve heard of s/a bikes where the scavenge pipe had fallen off (or was missing) without causing symptoms of wet sumping, as the oil level just rises a bit to the level of the gallery in the case, I’m not sure if this is the case with the semi unit engines but I thought it worth mentioning, before you strip it down!
It does sound like the cases are filling with oil.
I had a puzzling oil supply issue with a Honda gb500 (no supply to head/cam), I eventually worked out what was going wrong by “experimenting” with pieces of tube and bottles to hold supply/return oil, this may be an option for you before you strip it down *dunno*
Edit...I just re read yr 1st post and oil was coming out of the head oil feed “fast” when you had the oil coming out the breather, no way it should ever be “fast” ....the oil supply to the valves on my bike is a dribble at best. That indicates the cause is probably a blockage (intermittent?) between the tee to the head and the hole in the tank pipe doesn’t it?
I think Rocket Racer had this issue (during a rally) and the blockage was cleared quite easily.
Only just seen this post; I did have an intermittent oil return problem on my super rocket which seemed to be blockage related and only occured once to me then behaved. The present owner (with one in between) has replaced the original oil pump with an SRM one, had the return thoroughly cleaned and removed the oil filter on the return which was plumbed up via the tool box. That engine also has long had a bearing conversion with a centre feed. I believe its presently behaving again.
Cannot imagine the PRV likely to be related although the later A65 type plunger version far more reliable than the original ball bearing type.
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the a65 also had an oil warning light which would be helpful as the oil is not going where it should and if low oil pressure, will knock out the mains.
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I am going for the PRV out of desperation really I would not mind so much if the oil was not circulating but its returning perfectly with enough pressure that if I block the hole in the oil tank using my finger it blows the rocker feed pipe off.
The return to the tank is constant while normally it spits a bit as the return is more powerful than the feed, but the oil pump was on my other A10 and was only changed to fit a rev counter drive so in my eyes it cant be the pump.
The only bit of guesswork left for me now is the PRV not opening/closing at the correct pressure even tho it has a new ball and spring in it and appears to operate ok.
The one thing that keeps nagging at me is the scavenge (the crankcases) as these are the only parts that are untested by me as such. I bought them off ebay I think and maybe I missed damage to the scavenge pipe or something when I put it together.
It would not be so bad but the engine starts and runs perfectly and even the rocker box does not leak so stripping it down again will be a right pain
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do you mean you got the cases off ebay and didn't check your sucky tube? if so there may be an intermittent fault depending on revs and vibes and it could be pulling air at times and not oil when you are riding it and seem ok when its stood *conf2* *dunno2* just a thought because I haven't got a clue really and weird things like that happen, like two strokes increasing revs when they pull excess air from a joint and you spray joint with oil or something and find where its sucking air in. I will shut up now rambling again . time for bed said zeb *sleepy* *sleepy* *sleepy*
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G'day bb.
I was trying to think of a way to test the scavenge system for leaks.
Drop the sump plate and push the ball up the pipe a bit to drain any oil out. Remove the return line from the motor and with the plugs out kick her over till no oil comes out the pipe. Put rubber hose over the pipe and a finger over the scavenge pipe. Now suck on the hose and put tongue over the hole. See if it holds vacuum.
Or, put hose over scavenge pipe and block it. Then apply air pressure to the other hose and listen for any hissing. 20Lb pressure should be enough and be safe.
Cheers
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.......Or, put hose over scavenge pipe and block it. Then apply air pressure to the other hose and listen for any hissing. 20Lb pressure should be enough and be safe.......
Fairly much how I tested mine at Larry build, but figured the ball should block it anyway( guess a bit of hose will stop splatter?)
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G'day duTch.
I figured with a blocked hose it would eliminate the hiss coming from around the ball *dunno*
Cheers
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...I figured with a blocked hose it would eliminate the hiss coming from around the ball *dunno*.....
Fair call- I remembered I did it all before i putt the pump on too, so less oth er places to leak from.... and at same time made sure the feed side was clean and ball and spring doing their stuff
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hi bikerboy, i wonder if the crank gear is making good contact with the oil pump gear [ which do wear].is the crank washer missing , too much end float? if your problems started after swopping oil pumps i would go back to the old oil pump and test.
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In case you don't know, the SRM PRV is a different design. It has a piston, rather than a ball. I think that Triumphs had that design. I fitted one to my bike. I do not know if that is a superior design.
https://shop.srmclassicbikes.com/product/stainless-steel-pressure-release-valve-bsatriumph-twins
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Is it possible for the timed breather to create an intermittent fault?
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Hi RD and All,
Is it possible for the timed breather to create an intermittent fault
If the driving peg was barely engaging the breather sleeve due to either a worn casing or the driving dog not positioned correctly in the gear then Maybe??
John
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with all the investigations you have done yourself and the advice from the knowledgeable guys on here,
we often look for deep issues without always checking the simple things first
we all tend to think the worst when it is your own bike
is there a chance the flexi oil pipes are swapped over from their correct position
just a thought
but our sympathies are with you
and We will get it sorted between us
Clive1
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More thoughts. Seems it is intermittermently wet-sumping, causing the breather to throw out the contents of the sump. And do they!
I can think of two possibilities: the wire pin in the pickup pipe is missing, meaning the anti-drain ball can go right up and block the pipe, or the sump gauze is too fine and oil can't drain through it fast enough to get to the return suction pipe. Often wondered about the latter ever since I had a wet-sumping with oil pumping out via breather. I had already drained the sump (via the drain plug). Or so I thought. Actually I'd only drained a little and the rest was 'hiding' above the gauze, presumably held there by vacuum. I think most of the oil actually drains down through the hole the pickup pipe goes through rather than the gauze itself. My view is that the mesh supplied these days is a little too fine..
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Good point about mesh size.
There is an old Triumph service note which gives that as a possible cause.
Same note also says that a scavenge pipe end being too close to the sump bottom can also be a cause.
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The mesh size is definitely worth checking....fwiw, I discovered the brass mesh strainer around the pickup in my Gutzzi fell apart about four years ago so I replaced it with some 100 wire stainless mesh because I figured the 40 wire was too coarse and listed replacement ones looked too dodgy.... I had to pull the sump soon after to replace a seal and found the mesh had sucked a big tear hole *eek*.....so sourced some new brass not so fine and did it again- still monitoring it (nb, the strainer is~70mm dia. x 50mm high)..
In addition, as far as I can tell from the online images, the SRM type gauze is only a flat disc whereas the original item is cylindrical and allow much more flow..... *dunno*
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Just another thought, though I’m clutching at straws here – when I rebuilt my A10 I couldn’t get a proper oil flow (return to tank was a light dribble). The pump mating face was flat and I’d stripped and checked the pump. Everything was in order and I was really without a clue.
Then someone (forget who) on this site suggested a pump gasket with bigger holes. Couldn’t see why that’d make a difference, as the gasket mated with both c’case and pump holes OK, but tried it anyway. Success – a positively gushing return flow.
So, does your gasket have oversize holes – and after all the stripping and checking is the lone gasket at pump drive end still in place? Obviously the latter doesn’t apply if using the one piece gasket.
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There are some very nasty pump to crankcase gaskets offered.
Photo top right is the very nasty one, note the small holes, smaller than those in pump and case thus masking the oilway and reducing flow, also the mounting holes are too large and allow the gasket to be displaced.
Top left is a genuine BSA new old stock, see the larger oil holes and smaller mounting holes.
Bottom is SRM gasket extended to deal with the spacing of the pump on the front mounting stud. The large hole is for the modified anti syphon ball used on the end feed conversion.
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Another thought – if the rocker feed is excessive, the oil pump will draw from the tank, but not all will be returned. Some will start accumulating in the crankcase, causing wet sumping. I can think of two reason this may happen: the rocker banjo holes are too big, or the tank breather is blocked.
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Firstly thanks to all for your ideas and I will answer as I can
Musky
I did exactly that with a hose but I doubt that I went up to 20 psi so good call a recheck on that one
Gauze too tight, now thats not a bad call I have checked that the sump pipe has not been bent down to hit the pump and that has a load of clearance but that gauze is tight maybe I should check that out
Yes the crankcases are untested but I obviously checked all the oilways and blew them thru but the one from the PRV valve still worries me its tiny and maybe some crap has got in ther to block that.
The breather slipping as well is doubtful but well worth a check
When it comes to the oil pump, yes it has the spacing washer behind the drive and yes it has the fibre washer under the front bold. As for the gasket I always specifically check the holes line up perfectly knowing what gaskets are like nowadays.
The oil pump was not changed as such, it was on my other A10 and running fine but I put a rev counter drive on that and used the pump on the plunger engine when I rebuilt it so in my eyes it should be good.
Oil lines round the wrong way? Thats not really possible on the plunger as its totally different to the swinging arm model
End float I managed to get down to 2 thou which is pretty good in itself, I did use shims instead of making a one piece shim but there is no sign of anything in the sump that would indicate them breaking up, plus its done it from the start and I have only done 100 miles on it now
I will say I have dropped the sump 3 times now and on two occasions I have considered it had too much oil in it so my next move is firstly to degrease the damned thing its coated in oil yet again but at least I know it wont rust :(
Next I am going to take the PRV out of one of my running A10's just in case and put it in this one as a test
If that fails I am going to strip the timing case side down, check the breather location and send the oil pump away for a recon unit, a guy on the south coast has said he will do a recon exchange pump for about £85 which is not unreasonable.
While the pump is off I am going to (yet again) whack an air line on all the oilways particularly the one down to the sump to see if that has some form of a leak or something in it.
If all that fails I might seriously consider setting fire to it :(
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i think we have all been there bikerboy.
i rebuilt a plunger engine and hadnt noticed that the plug for the prv to camshaft gallery was missing.oil ***** out everywhere and i thought i had cracked cases.
you learn so much more on the second engine rebuild.
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bikerboy - know how you feel - I was on the brink of smashing up my GF when it suddenly started refusing to pump oil soon after a rebuild. Spent hours on it, getting nowhere. Never did find the cause, but it's OK now.
Before you start stripping things and throwing money at it, try the simple ones first.
Is the tank breather clear? A bit of hose should quickly confirm that.
Are the rocker banjo bolts the right ones? If the holes are too big, that could cause your problem as the return to tank would be diminished.
Re the sump gauze - that's only really to prevent crap from getting to the pump and damaging its teeth. Most filtration is done by sedimentation in the tank so, provided your engine is clean, try running it without the gauze for a few miles.
Lastly, on SA models the sump pickup pipe has a pin welded in it just above the ball to prevent the anti-drain ball from going too high. Does the plunger have a pin as well? Because if they're missing, apparently the ball can rise too far and block the return pipe.
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Well this gets even stranger and I have decided it has to be a blockage in the crankcase oilways somewhere.
I have stripped, cleaned and swapped parts with my other A10 which runs fine.
Drain the sump to make sure it had not wet sumped. Topped up the oil and everything worked perfect and the oil returned perfectly. Once the bike warms up the oil pressure coming back to the tank is ridiculous, if i blip the throttle it comes out of the return pipe in the tank so hard it flies out of the oil tank literally about 3 feet and then it starts coming out of the engine breather.
The only thing I can guess at is that the oilway from the pressure relief valve is blocked and the valve is not being allowed to relieve the pressure. I cannot think of any other possibility. The pump is hardly going to pump harder or increase pressure when it warms up so what else is left? One other faint hope is that the tophat breather on the end of the cam is some sort of freak part with the locating hole in the wrong place but I think thats highly unlikely.
It has taken me a while to have a good look because when the petrol tank decided to start leaking I got so peed off with the heap of **** that I simply could not be bothered to even look at it.
Thank god I have 6 bikes so had 5 others to play with :)
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I am afraid i cannot help with those oil pressure problems bikerboy but i can relate to your frustration and anger. If possible it is best to turn away and leave well alone for a while. Came close to putting a sledge and grinder to mine not so long ago. Foibles is a word, usually with a lot of expletives with it. Have since turned a corner and am currently enjoying the beast.
Good luck, i'm sure someone will be along soon with something useful to say.
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Well this gets even stranger and I have decided it has to be a blockage in the crankcase oilways somewhere.
I have stripped, cleaned and swapped parts with my other A10 which runs fine.
Drain the sump to make sure it had not wet sumped. Topped up the oil and everything worked perfect and the oil returned perfectly. Once the bike warms up the oil pressure coming back to the tank is ridiculous, if i blip the throttle it comes out of the return pipe in the tank so hard it flies out of the oil tank literally about 3 feet and then it starts coming out of the engine breather.
The only thing I can guess at is that the oilway from the pressure relief valve is blocked and the valve is not being allowed to relieve the pressure. I cannot think of any other possibility. The pump is hardly going to pump harder or increase pressure when it warms up so what else is left? One other faint hope is that the tophat breather on the end of the cam is some sort of freak part with the locating hole in the wrong place but I think thats highly unlikely.
It has taken me a while to have a good look because when the petrol tank decided to start leaking I got so peed off with the heap of **** that I simply could not be bothered to even look at it.
Thank god I have 6 bikes so had 5 others to play with :)
Ive not read the whole thread sorry, but the pressure relief valve is not in the return circuit (eg oil pumped by the pumps return side) so the relief valve cannot be the source of the problem?
If there is pressure in the return circuit then there is blockage between the pump and the oil tank return outlet in the tank, given you are seeing pressure at the tank outlet i suspect thats where the blockage must be, but its a very odd problem. Normally the return side operates at very low pressure as there is nothing significant impeding the flow back to the oil tank, there is a deliberate slight restriction in the banjo on the tank, so a small proportion if the return oil “diverts” up the small bore copper pipe up to the valve gear, and some bikes have a filter that should only be a small restriction.
A quick test would be to remove the pipe off the return side of the oil tank and see if it flows out slowly, The pumps do not move a lot of oil even at high revs so the level in the tank will not drop too much while you do that test.
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Just had a read thro' from the beginning.
With a good 3 foot spit from the tank return, there can't be much wrong with the scavenge side. Can't guess how this is actually set up, on my plunger the return oil come out of a hole in the side of the pipe. But a high pressure would normally indicate to me that there is some restriction in that pipe, either a partial blockage in the pipe, or the exit hole is offering a restriction. Did I understand the pressure blew the rocker feed pipe? It's almost as if feed and return are mixing to return a far greater return volume and the most likely culprit for this to happen is something within the oilpump body.
Whatever the basic fault, as a consequence higher than normal flow is being directed to the rocker feed. This small but constant higher than designed volume will tend to fill the sump, as extra oil scavenged is being simply returned to the sump in a continuous cycle, eventually exceeding the scavenge capacity, so when the sump fills, out of the breather it comes.
So a few easy things to check....a restriction in the return pipe and exit hole in the oil tank, plus anything in the rocker feed which would tend to offer an easier route for flow in preference to returning to the tank. Thinking big holes in the banjo bolts.
With the PRV removed, have a look for a hole leading down (early cases, oil blow off to pump cavity) or later cases, upwards, this leads to cam trough. Worth poking with a fine wire or a blow with the airline just to make sure the PRV has somewhere to vent. If the pump can't blow off excess pressure, where else can it go? Back into the scavenge side of the pump via a crack in the body, gasket fault or a missing or loose driven gear spindle? We assume the PRV is not jammed shut.
The symptoms indicate the pump is producing a working pressure, but there is something quirky about the balance between flow and return, and as the motor runs fine, is it just the scavenge that's the culprit? If you have a filter in the return, it should be fitted before the T off to the rockers. A restricting filter after the T will force more volume to the rockers as outlined.
Well worth first trying a non restricted return test as suggested by KiWi, before you get the timing cover and pump off, maybe a short road test with a hose direct from the return pipe on the crankcase into the open top of the tank to eliminate any possible restriction within the tank inlet pipe.
Swarfy.
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Just to answer a few questions.
The oil pump was used and worked fine on my other A10 I only changed it to fit a rev counter to it, so I know the pump is good.
I have swapped PRV's with my other bike so I know thats good as thats done 10'000 miles since I built it.
All of the flexible oil pipes are new and have also been replaced again with new. The rocker feed pipe is also new and has also been replaced with new again. The only time the rocker pipe blew off is when I put my finger over the return in the tank cos it was bursting out all over the place.
On tickover the oil just returns a bit quick but as soon as you blip the throttle is when it spurts like a demon.
So this is my logic.
Firstly the feed must be fine or it would not return like a lunatic it would splutter as the return side of the pump is bigger than the feed anyway.
Now as it insists on pumping out of the breather in the crankcase and its returning like a lunatic then there simply must be too much pressure in the crankcase.
My next thought is the only thing that relieves that pressure in the engine is the PRV. Now if I know the valve itself is good so then my logic tells me that the oil ways from the PRV must be blocked thereby not relieving the pressure.
What else can it be?
There is one tiny oil way from the PRV that is drilled thru the crankcase (its blocked at the front after the drilling) which must be where the PRV directs the oil when it relieves the pressure. I obviously blew this out when I built the engine but all I can think is that when the engine gets warm that this gets blocked or partially blocked causing the problem.
Every other part of the engine barrels, head, rocker box, camshaft etc. except for the crankcases I have used in the past. Obviously the big ends, and bearings are all new but they wont be causing this.
The oil pipes, the first bit from the engine is solid and was well cleaned and there are only a couple of inches of flexible oil pipe (all renewed twice now) the oil tank has been off 3 times and there is no way there is a blockage in there, trust me I have mini brushes etc and made sure that was clear AGAIN. I do not have an oil filter on the return side the oil system is totally standard with no modifications of any type except for the rocker feed being mainly rubber instead of 99% copper pipe but thats not blocked cos if I take the pipe off at the rocker box end the oil comes out quite happily.
In my eyes, obviously I have been trying to cure this on and off for over a year so have done a lot more than I have written on this article, all thats left is a complete engine strip and major inspection of the crankcases.
What choice do I have? If anybody has a better one then I will be more than willing to listen cos its already been line bored etc. so I dont really want to change crankcases if I can avoid it.
For those who think I might be a total thicko (you wont be the first to think it by the way ;) ) I got my first A10, this one as it happens, when I was 16. I am now nearly 64 so not a newbie in anybodies eyes and I can virtually build them in my sleep. Maybe thats where I went wrong on this one, dozed off and put the oil pump on upside down or something, and yes I do know thats impossible. Fitting the oil pump upside down I mean not me dozing off.
The most infuriating thing of the lot is that the damned thing is oil tight, even the rocker box and now I have to strip the damned thing apart :(
How on earth does one get an A10 oil tight when the pressure is too high? I cant normally get them 100% oil tight when the pressure is normal.
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Im disappointed *dunno* you did not think it worthwhile removing the return oil pipe and seeing how it returns oil into a catch tank but I also understand you don’t think there could possibly be a blockage in the tank.
You are right in thinking a high pressure in the crankcase could conceivably cause “spitting” at the oil tank outlet (I had thought about that, but discounted it) but to do so it would have to push air backwards through the gears of the return side of the pump.....possible but really unlikely?
This statement below I’m afraid is incorrect as the (timed) crankcase breather stops pressure build up in the cases, you had stated that oil comes out the crankcase breather vent (this being the one by the final drive sprocket) so I had assumed that the breather was checked and working but you know what they say about assumptions .......
“My next thought is the only thing that relieves that pressure in the engine is the PRV. Now if I know the valve itself is good so then my logic tells me that the oil ways from the PRV must be blocked thereby not relieving the pressure”
The job of the PRV is simply to prevent overly high oil pressure occurring, it does this by “diverting” oil to the crankcase when it exceeds (say) 60 psi, in practice most oil pumps can only get to that pressure when the oil is cold, when it takes more pressure than “normal” to push the oil through the big ends. When the oil is hot, in most engines the PRV is not called upon to limit pressure as it never gets to 60psi (There may well be exceptions to this State of affairs, from those with SRM pumps and newly built engines with new oil).
The oil pump really does turn slowly, and pumps a surprisingly low volume of oil, and it may help your understanding to see this in practice by removing the return pipe and observing the oil flow, noting even if the crankcase was pressurised (by say gases passing the rings) the amount of oil returning to the tank cannot exceed the amount pumped by the flow side of the pump.
Edit: I’ve just read the whole thread and you already observed the return but i still think it worth doing as it will show up any crankcase pressure build up, and also whether too much oil is going to the rockers, on that, the swing arm bikes have a “special” banjo at the oil tank that “bleeds” a small proportion of the return oil to the rockers. RDFella mentioned this a few posts ago. Given the return side only has in the region of 30% more capacity than the flow side its important that the “bleed” to the rockers is considerably less than 30% if the return volumn, for this reason a simple “TEE” to the rockers (as you mentioned early on) may not restrict the flow to the rockers enough, which would lead to a crankcase full of oil some minutes (maybe many minutes) later. Just a thought......
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bikerboy How wrong was I ? One of the downsides when attempting to offer assistance is that is is sometimes difficult to appreciate the knowledge and skill of the Forum Member with the problem.
This is why my suggestions are mainly biased towards the very basics, and possibly viewed as simply repeating established practice. Fine if you already know the what's what, but I hope of benefit those sufferers and newbies who don't.
So, looks like you know what you're doing, but the machine is about to win. Before ripping it to bits, I would try a simple open topped temporary oiltank, and just get an idea of how the oil is flowing as regards volume and pressure with no restriction on the return. As you have experience with these motors, I suggest forgetting the rocker feed for a short test, a direct connection to the feed and return plain pipes should do. Start with a drained sump, correct oil volume and see what happens. May save a load of work if the fault is simply the oiltank.
Good Luck with this one!
Swarfy.
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I'm joining this discussion late so apologies for perhaps missing some of the earlier posts. I must confess I haven't read everything but I reckon I've got the gist of it. Here's my two penn'orth....
I've seen pumps deliver from a wet sump and they don't squirt three feet even when the engine is revved! The holes in the rocker banjos are so small they wouldn't make that much difference if they were closed off altogether. In my opinion the return side is acquiring additional pressure from the crankcase pressure. Even though the crankcase breather seems to be working I suspect something wrong in this department so that crankcase pressure is pumping through the return side via the pickup pipe or via the gasket at the back of the pump. I would put an extra breather on a tappet cover. If you have a spare timing cover put a breather on that. I would also make absolutely certain the oil pump is seating properly. Sorry if this is repeating what you've already heard. Fundamentally, I think the crankcase pressure is finding its way into the oil return...somehow! The only other possibility I can think of is the oil return hole in the return pipe in the tank blocked or too small for another reason. Where else could such excess pressure be coming from? Good Luck!
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Excess pressure in the crankcase can come from a head gasket leaking into the pushrod tunnel.
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Hi
Time for a leak down test before pulling the top end part ?
Without going back to the start what type / make rings are fitted ?
A bad bore or cocked piston from a misaligned small end will cause lots of blow by
John
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Just a very brief observation, you mentioned a fibre washer under the forward fixing on the oil pump. You probably meant to say gasket, but just in case ( and I'm sure you are aware ) the forward circular gasket is the same thickness as the main pump gasket.
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Thanks for all your ideas because I really dont want to strip this engine down if I can avoid it, I will now try to answer those ideas.
One thing I probably did not emphasis is the way the engine runs. It runs wonderfully, it ticks over perfectly and is instantly responsive when blipped. Obviously its running in so I have not revved it to death but a quick blip and its great. I have done about 250 miles on it (and about 25 gallons of oil ;) and it starts and runs perfectly with no smoking and the plugs are a lovely colour.
Just a very brief observation, you mentioned a fibre washer under the forward fixing on the oil pump. You probably meant to say gasket, but just in case ( and I'm sure you are aware ) the forward circular gasket is the same thickness as the main pump gasket.
Yes its actually a very thin washer which I assume is fibre and it is fitted.
I’ve just read the whole thread and you already observed the return but i still think it worth doing as it will show up any crankcase pressure build up, and also whether too much oil is going to the rockers, on that, the swing arm bikes have a “special” banjo at the oil tank that “bleeds” a small proportion of the return oil to the rockers. RDFella mentioned this a few posts ago. Given the return side only has in the region of 30% more capacity than the flow side its important that the “bleed” to the rockers is considerably less than 30% if the return volumn, for this reason a simple “TEE” to the rockers (as you mentioned early on) may not restrict the flow to the rockers enough, which would lead to a crankcase full of oil some minutes (maybe many minutes) later. Just a thought......
I agree so I removed the Tee piece and refitted the standard plunger rocker feed which has not helped at all.
As you have experience with these motors, I suggest forgetting the rocker feed for a short test, a direct connection to the feed and return plain pipes should do. Start with a drained sump, correct oil volume and see what happens. May save a load of work if the fault is simply the oiltank.
Good idea one I will try when I can but I am fairly sure the oil tank is ok it was my first thought a blocked return but I have cleaned them again quite vigorously.
In my opinion the return side is acquiring additional pressure from the crankcase pressure. Even though the crankcase breather seems to be working I suspect something wrong in this department so that crankcase pressure is pumping through the return side via the pickup pipe or via the gasket at the back of the pump. I would put an extra breather on a tappet cover. If you have a spare timing cover put a breather on that. I would also make absolutely certain the oil pump is seating properly. Sorry if this is repeating what you've already heard. Fundamentally, I think the crankcase pressure is finding its way into the oil return...somehow! The only other possibility I can think of is the oil return hole in the return pipe in the tank blocked or too small for another reason. Where else could such excess pressure be coming from? Good Luck!
Firstly dont worry about repeating anything if it helps I will love you forever :). I had a rocker box breather on which did not seem to leak oil or improve things nor did there seem any pressure coming from it but I do find the idea of the crankcase pressure actually boosting the oil pressure a very sensible train of thought. I will definitely check the seating of the oil pump because that would possibly explain a few things.
Excess pressure in the crankcase can come from a head gasket leaking into the pushrod tunnel.
Now thats a good thought as I had that many years ago on another engine and it actually ended up with the pushrods being bent from the heat. I dont think thats my problem this time as a compression test was fine but the engine was not at running temperature when I did that test. That would also explain why the plugs are still a relatively good colour.
Time for a leak down test before pulling the top end part ?
Without going back to the start what type / make rings are fitted ?
A bad bore or cocked piston from a misaligned small end will cause lots of blow by
Another top idea particularly as I actually have a leakdown tester that I have only ever used once and that was not even on one of my engines.
The pistons and rings are heppolite but they are the old heppolite from many years ago, not the newer ones. I have quite a multitude of spares some of them I have had for 40 years and altho they looked ok and all measured ok thats a damed good shout. The problem is I cannot remember if I put new rings on them or they are original rings. They were obviously measured and gapped etc before fitting and the compression seems good but again those tests were done before it was at full working temperature.
A huge thanks for all your ideas I will investigate all in turn before I rip the engine out and set fire to it :)
It might take a few weeks before I get around to it because I do have other projects on the go but I really do appreciate everybodies input.
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Hi bikerboy,
Just another thought?
Have you shone a light down the plug holes to see if the bores have glazed preventing the rings from bedding in ?
John
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Have you shone a light down the plug holes to see if the bores have glazed preventing the rings from bedding in ?
Yes I did that when I ran the compression test, I have actually done a lot more than I have posted on here but if I tried to describe every check that I had done then this article would be 5 pages before anybody else commented.
I think the most misleading thing is that the engine runs so damned well. When I first started the bike it fired first kick and started second kick. Even now after not touching it for 3 months (due to pure anger as much as other projects) it started first kick. It sits there ticking over lovely and holds at 55 mph like it could sit there all day, it probably could if I had an oil tanker following me :)
my plan to proceed is as follows:
Disconnect the return pipe and run it to a gallon can or something to take the oil tank out of the equation. Some will say disconnect the rocker feed but I am not happy doing that as its all brand new valves and guides and I dont want one of them to pick up.
When and if that fails, remove the timing cover and check the oil pump is sitting nicely, I might even change it I have a few of them.
When and if that fails, remove the rear rocker box cover and run it without to normal temp to see if the head gasket is blowing into the push rod tunnel, altho my endescope might tell me that with running it there are bound to be signs on the push rods if it is.
If all else fails then make sure its hot and get the leakdown tester on to it, 100 PSI should be enough.
If none of those tests diagnose the problem then its going to be a case of head and barrels of at least which will be a pain but I want to find out exactly whats up.
A very vague memory tells me that the piston rings and barrels were all kept together because I have used them before but I cant swear to that.
I might just buy a new set of pistons for the hell of it anyway.
It has got the big valve alloy head on it which is a right pain to get on and off but this is the price we pay for collecting thse old english bikes.
If all else fails I might set alight to it and go and buy a kawa*****.................................... Ok no!!!!!!!! its not quite driven me that crazy yet :)
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Have you shone a light down the plug holes to see if the bores have glazed preventing the rings from bedding in ?
Yes I did that when I ran the compression test, I have actually done a lot more than I have posted on here but if I tried to describe every check that I had done then this article would be 5 pages before anybody else commented.
I think the most misleading thing is that the engine runs so damned well. When I first started the bike it fired first kick and started second kick. Even now after not touching it for 3 months (due to pure anger as much as other projects) it started first kick. It sits there ticking over lovely and holds at 55 mph like it could sit there all day, it probably could if I had an oil tanker following me :)
my plan to proceed is as follows:
Disconnect the return pipe and run it to a gallon can or something to take the oil tank out of the equation. Some will say disconnect the rocker feed but I am not happy doing that as its all brand new valves and guides and I dont want one of them to pick up.
When and if that fails, remove the timing cover and check the oil pump is sitting nicely, I might even change it I have a few of them.
When and if that fails, remove the rear rocker box cover and run it without to normal temp to see if the head gasket is blowing into the push rod tunnel, altho my endescope might tell me that with running it there are bound to be signs on the push rods if it is.
If all else fails then make sure its hot and get the leakdown tester on to it, 100 PSI should be enough.
If none of those tests diagnose the problem then its going to be a case of head and barrels of at least which will be a pain but I want to find out exactly whats up.
A very vague memory tells me that the piston rings and barrels were all kept together because I have used them before but I cant swear to that.
I might just buy a new set of pistons for the hell of it anyway.
It has got the big valve alloy head on it which is a right pain to get on and off but this is the price we pay for collecting thse old english bikes.
If all else fails I might set alight to it and go and buy a kawa*****.................................... Ok no!!!!!!!! its not quite driven me that crazy yet :)
On my s/a bike its not possible to disconnect the return pipe and not disconnect the rocker feed at the same time? Are plungers plumbed differently to the swing arm bikes? Makes me wonder how the rocker feed is plumbed into the return pipe, can you show how with a photo?
Another test could be to run it without the outer timing cover on so you can see if the oil level builds up in the sump or if the oil pump leaks, I’ve not done this so don’t know how messy it is, maybe someone else can comment?
The rocker feed on my bike is a few drops per second, just a dribble really, as very little oil is needed in the rocker box (and there is considerably less than 35% to “spare” from the return oil supply for the rocker box anyway) Theres also plenty of “oil mist” coming up the barrel so personally I think you would be ok if you only run it without the pressure feed for a few mins, you could take the rocker covers off and squirt some oil in around the guides before doing the test, then replace the covers, if still concerned.
I could be wrong but i still don’t think pressure in the cases will cause the return oil to be pressurised, so i think you either have one problem (with the oil return) or two unrelated problems (the second being pressure in the cases). I know of an A10 with piston blowby issues that were bad enough to keep popping the drive shaft oil seal out of place, but not, from memory, cause any issues with the oil return to the tank.
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yes but no but maybe , has the pump gasket blown across the oil ways and to the inside of the engine? could be part of the problem as well as wrong breather timer thingy or breather cork disintegrated *eek* does the oil get black quick, I should hope not with new valve gear but these things can bite us, apart from that I have no idea so will shut up! good luck in the investigation, I can't wait to find out what the problem was, -- not is *smile*
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G'day bb, what a mess (pun intended).
I agree with KiwiGF and can't see how crankcase pressure can affect return oil pressure.
The sump filling to the extent of blowing out the breather means the return side of the pump isn't keeping up with the feed side or something is stopping it (blockage).
Just a random thought as I don't have any literature anymore. I think the A50/65 pump spins the opposite way to the A7/10. If this is so, could you have a later worm drive. I know it would be hard to reverse the hoses on a plunger but not impossible.
Clutching at straws is hard with oily hands.
Cheers
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Had a similar distressing problem with the A10 a few years back.
A 20 mile run to work would result in most of the oil tank content ending up on the road through the breather. Changed oil pipes, blew out oil ways, stripped and check the pump. All the usual. Put it back together and no improvement. Repeated the process still no improvement.
In desperation checked the return pipe in the oil tank and found it obstructed and allowing only part of the return oil to get back to the tank. Had to open the top of the pipe and push obstruction out. It looked like bits of wire wool. How did it get there?? Sealed top of pipe. refilled tank problem solved.
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G'day bb, what a mess (pun intended).
I agree with KiwiGF and can't see how crankcase pressure can affect return oil pressure.
The sump filling to the extent of blowing out the breather means the return side of the pump isn't keeping up with the feed side or something is stopping it (blockage).
Just a random thought as I don't have any literature anymore. I think the A50/65 pump spins the opposite way to the A7/10. If this is so, could you have a later worm drive. I know it would be hard to reverse the hoses on a plunger but not impossible.
Clutching at straws is hard with oily hands.
Cheers
The a65 pump does turn the opposite way, which is why you have to fit an A10 drive/ worm section to the A65 body to get the resultant bastardised pump to fit an A10, its a good mod tho (i have done it). To fit a complete a65 pump to an A10 one would have to put the “reverse” worm on the crank, which would take some doing! But stranger things have happened I guess.
Reversing the oil pipes to “correct” an A65 pump working in an A10 in reverse would not work, as the return/scavenge side would still have less capacity than the pump side? *dunno* makes my head hurt.
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Reversing the oil pipes to “correct” an A65 pump working in an A10 in reverse would not work, as the return/scavenge side would still have less capacity than the pump side? *dunno* makes my head hurt.
G'day Kiwi.
That's what seems to be happening.
JulianS could be on a winner.
Cheers
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The A65 pump rotates the same direction as the A10. The a65 worm drives the pump gears furthest from the crankcase/pump joint, the A10 worm drives the gears nearest the joint. The A65 worm and worm gear on the crank have an opposite cut to the A10 so the pump rotates in the same direction as the A10, as required by the oilways in the crankcase, which are basically the same form both models. If it had the same cut the pump would rotate in the opposite direction.
The A65 pump nose is longer than the A10 and the worm is longer so you cannot fit the A65 worm into the A10 nose.
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On my s/a bike its not possible to disconnect the return pipe and not disconnect the rocker feed at the same time?
Dont have a pic but its a steel tube in the return line with a take off but all I would do is disconnect the rocker pipe at the rubber joint and stick a bolt in it to stop feed to the rockers so its easily done. The connection is just before the return pipe fits to the tank so on a plunger its easy to do, I know what you mean for the swinging arm model as the take off is actually off the tube coming out of the oil tank.
does the oil get black quick
It does not appear to
I think the A50/65 pump spins the opposite way to the A7/10. If this is so, could you have a later worm drive. I know it would be hard to reverse the hoses on a plunger but not impossible
The A65 worm gear ann the A10 pump would never marry together or visa versa as the worm drive runs in the opposite direction. I know that for sure cos I have my A65 engine half built :)
It would be a stunning feat to cross the oil lines over and if I did it would not be returning at all nor would it be getting any oil down to the engine cos the level would need to be above the return stick in the tank
In desperation checked the return pipe in the oil tank and found it obstructed and allowing only part of the return oil to get back to the tank. Had to open the top of the pipe and push obstruction out. It looked like bits of wire wool. How did it get there?? Sealed top of pipe. refilled tank problem solved.
I have pushed brazing rods down the return pipe in the tank and blown it out with about 150 PSI because that was my first suspicion so I am 100% sure there is no blockage in the tank or the lines but I do aim to hook the return pipe up to a separate container to take that possibility totally out of the equation.
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G'day JulianS & bb.
Thanks for putting my "random thought" to bed. I learn something every day.
Cheers
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G'day JulianS & bb.
Thanks for putting my "random thought" to bed. I learn something every day.
Cheers
Here is a good thread on the A65 and A10 oil pump differences, and the worm gear differences, I see Julians statement above the pump rotates the same way as the A10 so this really does my head in *pull hair out*
Possibly going off topic here tho *shh*
https://www.a7a10.net/forum/index.php?topic=5829.msg92030#msg92030
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Hi.
Iv'e been following this post with interest & don't think Iv'e seen mentioned the anti- siphon ball & spring & cap screw thats fitted from the inside of the crankcase. Is It there? If not, this could explain a massive over feed of oil. The engine won't seize as the crankshaft will have plenty of "splash' lube.
Just a thought.
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Yes its there, it still wet sumps mind but for the minute I have fitted a tap in the oil line to avoid that happening while I sort this problem out. I have prodded that from the oil pump end in case the spring had broken or something else bizzare and its in there and springing back even if its not much of a seal. I would do the A65 type mod if I knew how long the spring should be but I have never seen anybody that knows for sure so will not risk starving the crank of oil by guessing at a spring length.
I did have an anti wet sumping valve in but suspected that might be effecting it so temporarily I fitted a standard tap, if I manage to fix the problem I will invest in one of those taps that stops it starting if its not switched on but I am not willing to spend another £50 on it yet in case I do decide to set the damned thing alight :)
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Maybe time to 'bite the bullet' & strip the cases to check the pick-up tube as others have suggested. You seem to have covered
& re-covered everything else in the oil system. You've mentioned a couple of times there was too much oil in the sump when drained after a ride but have a healthy return flow. ( How much ? 1/2 liter , 1 liter? ) Tends to indicate the sump is filling to a higher level than its supposed to.
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This posting now runs to 6 pages with a member tearing his hair out trying to diagnose a BSA A series lubrication problem. And how many similar posts have there been? Wasn’t that long ago I was in a similar situation with my own GF (for the 2nd time). I just don’t get why this model’s lubrication system should be so uniquely unreliable. The singles aren’t, nor indeed any other engine I can recall – and I’ve worked on a few over the last 55+yrs – and a wide range too. Only failure I remember was on a TE20 Ferguson, where the oil pump gear fell off. Stupid design, a gear of around 3” dia just pressed onto the pump’s ½” shaft. Next one I pinned and it’s still going 50yrs later. Certainly takes the shine off owning a BSA twin.
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You've mentioned a couple of times there was too much oil in the sump when drained after a ride
Thats only been after leaving it a while I have never ridden it let it cool and then taken the sump off its always been a few days/weeks later
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Hi bikerboy,
I would do the A65 type mod if I knew how long the spring should be but I have never seen anybody that knows for sure so will not risk starving the crank of oil by guessing at a spring length.
I posted the information and photos of the mod a while ago
https://www.a7a10.net/forum/index.php?topic=13668.msg111568;topicseen#msg111568
John
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John
Thanks very much for that info if I have to strip the cases down I will do that for sure :)
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john very good!! the berger build is getting the conversion as well as an oil drilling for a pressure gauge, it might end up with a dashboard like a mk1 capri gtlxr *lol*
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. . . . one tip I sometimes use
Bend the pushrod comb so that it comes down to sit on the top fin of the cylinder head. Use one of those spring steel chassis clips to slide over the fin and the comb holding it nicely in place.
Thought I'd try this, modded a comb so it could be clamped firmly to the top fin on LH side of head - and the whole caboodle went on first time, no messing. Easiest ever reassembly.
Will find out if it works twice when I check-tighten the head in a bit . . . !
So - a very good tip - thanks!
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You are very welcome *smile*
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When the return is too slow and engine fills up and blows the oil through the breather, remove the sump plate. Push a rubber hose over the pick-up tube and insert your airgun. When blowing air into this contraption look and hear for leaks. Check that the ball is free moving and has still its upper stop in the pick-up tube - otherwise it might seal the tube enough to reduce/stop the return. The possible outside leak is the aluminium pin that is inserted into the return bore right above the frame tube, the inside leaks can only be at the oilpump gasket or where the pick-up tube is inserted into the crankcase or the tube is cracked somewhere, allowing air to be sucked instead of oil. If this is all good, there is only a damaged return pump or a problem in the hose or tube and connector going into the oiltank.
cheers
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This engine sounds like it is wet sumping when in use, when the pump is running. Not a leaving it standing issue. Ball valves will cure a parked non running wet sump but an engine that is pumping oil both ways should by definition return more than it feeds. So the scavenge balance is compromised, could be anywhere from the rocker feed taking all the return (if lines obstructed), or a leak in the scavenge pipe or loose pump. Its not PRV or pressure related, any excess oil in a crank will end up blowing out the breather, nothing to do with crankcase pressure or breather timing. Presumably you're not running a return filter which can obstruct the return feed.
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BSAmoto
Great idea when I get around to looking at the plunger again I will do exactly that thank you.
Rocket Racer
Thanks for the input and altho I know the pipes are clear yours are good observations
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Watching this thread, there are a lot more capable of giving advice than me, a question after a run and giving bike an hour to drain, how much oil would be expected to drain from sump, Ive got 100mm after a run, give a few days its more , which I allow for and drain again or run, 51 A7, just lets the oil go down :!
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the more i consider a 20mm deep threaded insert to house the anti syphon ball the more i like the idea. removable to clean and check seating surface and could even dowel into the pump body. a brass insert would be easy to make. one side of the bsa lubrication shortcomings taken care off.
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G'day Steve.
About a cup (250ml) or less should remain (after 15 minutes of drain down).
G'day Edboy.
Easier to do the A50/65 modification.
Cheers
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hello muskrat,
i m not convinced with the a65 conversion. is the oil way oversize to the steel ball and oil flow is around the ball bearing. also is the spring able to move around side to side ?
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When I converted mine to the A65 type system I made the rear plug with a small dimple to locate the spring centrally in the hole (1/4 spring in 5/16 hole) as I didn't want it lying on the bottom. I found the conversion made no difference and it still wet sumped until I fitted a valve in the oil line. I believe the A10 and A65 springs are different, but some suppliers provide the same spring for both. Maybe the stronger spring is needed, but mine's cured with the valve now.
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Hi All,
Edboy, Yes and yes to your questions,
I recently posted further information on the conversion when I was modifying a bush equipped engine.
RD,
The conversion will work 100% only if the oil pump does not leak. Almost all original pumps leak along the drive spindles and between the joints on the body. The bodies can also be porus and leak through the mazac
The new pumps have a seal on the drive spindle which helps considerably..
John
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great info john. i m off to the shed. there must be a spare pump somewhere.
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Thanks Musky thats about the amount I have after drain down, a bit less.
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Wow is it really 2 years since I abandoned this project?
Well I have picked it up again now and already I am confused.
Dropped the sump first and checked the oil level. Sump had some oil in it (obviously) but not a lot. Seeing as how it used to wet sump, took the sump off filled the oil tank stuck a container under the engine and 48 hours later no sign of wet sumping whatsoever. Kicked the engine over a few times nad left another 24 hours still no sign of wet sumping so maybe its time to start it up and see if it has fixed itself which I find highly unlikely.
By the way never abandoned it as such. The petrol tank decided to leak and it took me time to source anothe tank and get it painted up. Thats why I have not bothered with at so much lately.
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G'day BB.
Just spent an hour going right back to page 1.
One thing that hasn't been mentioned is the joint from crank case to the feed/return pipe fitting and it's dowel. If the dowel is damaged or missing the holes won't line up 100% and could restrict the return.
On my recent plunger rebuild I noticed the dowel looked a little sad so replaced it.
Cheers
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Me likewise. On the face of it, except for the joint to the crankcase, every part of the system took centre stage at some point. Easily overlooked, that dowel keeps the feed and return pipe oilways in line with the crankcase drillings.
Swarfy.
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Thanks for the comments in my case the dowells were both not the greatest so I made and fitted new ones when I built it.
What I have done so far is dropped the sump. No sign of wet sumping. I have put a rubber pipe on the scavenge pipe and blew up it with an airline. As expected it blows back to the oil tank and seems ok.
I am going to now start it with the scavenge pipe in a jar of oil to physically watch it scavenge and make sure it is scavenging more than its putting into the sump. I am not that happy about running it with the sump off but it does seem to be the next logical step. I only aim to run it for a minute or two.
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What I have done so far is dropped the sump. No sign of wet sumping. I have put a rubber pipe on the scavenge pipe and blew up it with an airline. As expected it blows back to the oil tank and seems ok.
G'day BB.
There would have been a fair amount of restriction as the air has to pass through the pump gears. If it was an easy blow I'd be worried about the pump.
Cheers
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That airline test will certainly allow air to the tank, but it should not be a free flow. Like Musky says, the pump gears are in the way. The real test is to remove the pump and test for free flow from the return oil drilling to the tank. Then proceed to that pesky pick up pipe. With the airline on the pipe oilway there should be no flow. The ball valve seals the pipe, and the pipe is sealed to the crankcase. Any sign of a hiss means a leak and the pump will scavenge air rather than oil. Make sure the ball has enough lift on it to allow a good return oil flow, how this valve is assembled is on the Forum.
If these basics check out, it's down to the pump.
Swarfy.
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Evening all. Firstly it was not a free running air back to the tank but it was reaching there eventually. Started the engine today with the sump off and a pipe on the scavenge pipe altho to be fair I did find that a bit weird and worrying. The scavenge part worked perfectly and needless to say oil was running out of the sump at a reasonable rate. Put the sump back on, checked the levels etc and everything was perfect "for now".
Altho the pump whould be high on my list of suspects as I mentioned before I had that on one of my other bikes for over a year and only changed it because I wanted a rev counter drive type so I really cant see it being the pump. I have come to the conclusion that I will use it a bit with a very watchful eye on the oil situation and should it start to pump out of the breather again I will try a different pump but then I am going to strip the engine down and change crankcases. Thats a right pain because obviously it has been line bored, shimmed etc and it will need doing all over again.
The most infuriating thing is that even tho I have not touched it for 2 years I started immediately and ran wonderfully, one of the quietest engines I have ever built to be honest. So thanks for all your help I will see how it reacts over the next month or so altho with how cold it is in the UK at the moment any test runs will be pretty short for sure :)
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The bike is a freak thats my honest opinion :(
It no longer wet sumps unless the engine is running!!!!!! Then it pumps out of the engine breather at roughly the same pressure that it returns to the tank and it returns to the tank at a very consistent rate. Have taken the oil pump off, have "yet again" blown through all the oilways they are clear. It has to be a scavenge problem even if I can see it returning nicely to the tank. I took the sump off before starting it and no oil came out, it had not wet sumped since last taking the sump off. Started it, runs great returns to the tank and pumps out of the engine breather. Dropped the sump and over half a pint came out of the sump, the oil tank level dropped over an inch as soon as it started even tho the return looked good.
It can only be the pump or something wrong with the scavenge pipe in the crankcase. Broke the inner timing case gasket so fitted a new pump but cant put it back together until tomorrow when I get a gasket. If it still pumps out of the breather then its going to be another engine strip :(
Either way its very intermittent because I must have started it 20 times over the last two weeks and this is the first time its pumped out of the engine breather like it did when it was first built.
The only good news is that I have one of the shorter bike ramps so the rear wheel is in mid-air so to speak. When I was running it the rear wheel was freewheeling as I blipped the throttle and the good news is the breather lubricated my chain completely and my workshop floor :(
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*pull hair out*
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G'day BB. *pull hair out* *rant* *help* *problem*
It's gotta be the scavenge pipe, loose fit into the case *????*
A bit off left field. The rocker banjo's are the correct ones and not off a single. Singles have a larger hole. Too much could be going up there and overwhelming the scavenge side.
Cheers
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This lubrication system depends on the balance between the rate of supply and the rate of return. With the scavenge side having the greater pumping capacity, the balance is in favour of the return. Have we tried a pipe on the pickup pipe in a bowl to catch the crankcase drain down, motor running to observe the scavenge working?
Otherwise the pump is delivering too much oil, somehow. Think of anti wet sump spring plug leaking, main bearing bush leak around the outside, or simply the PRV stuck open. I'm no hydraulic engineer, but a high flow rate because of low resistance could be the answer. Big ends surviving on copious splash? If you're lucky enough to have a rubber join in the rocker line try pinching this off to restrict rocker feed as Musky's thought.
Swarfy.
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Hi All,
I have had an experience where a needle roller converted A10 gave trouble by pissing oil out the breather,
Eventually I found a leak in the end feed to the crank,
For some unknown reason this must have sprayed oil at the timing gears????
That carried the oil up to the breather..
This is of no help to the question of the sump filling with oil though *conf*
John
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It's gotta be the scavenge pipe, loose fit into the case
checked and its not worse luck
Have we tried a pipe on the pickup pipe in a bowl to catch the crankcase drain down, motor running to observe the scavenge working?
Yep scavenged perfectly
Think of anti wet sump spring plug leaking,
checked working perfectly no sign of wet sumping even if left for a month
or simply the PRV stuck open
have swapped that with my other a10 which worked perfectly with its own PRV and works perfectly with the one out of this bike.
Oh well engine strip I guess :(
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G'day BB.
Before you start pulling it down try cutting off the rocker feed as swarfy suggested.
The rocker feed is teed off the return line. If too much is going that way it would give the impression of too much feed to the motor and overwhelming the scavenge side with oil building up in the crankcase.
Cheers
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so fitted a new pump but cant put it back together until tomorrow when I get a gasket. If it still pumps out of the breather then its going to be another engine strip
Can't see it's an engine problem. Are you checking the sump for oil before each start? If there's half a pint in there it will chuck it out of the breather when you start. Some bikes don't wet sump. others do after a week or more, some after just a couple of days or so.
In the above quote, is that another pump fitted - and did you strip the previous one to check the internals?
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i removed the 5/16th bolt in my home made sump plug conversion many years ago and not a drop of oil came out untill i jumped on the kick start then loads came out. , maybe a vacuum was holding it in there,
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i removed the 5/16th bolt in my home made sump plug conversion many years ago and not a drop of oil came out untill i jumped on the kick start then loads came out. , maybe a vacuum was holding it in there,
Got caught out the same way - only I presumed the sump was empty and started up, dumping a quart of oil on the floor in seconds.....
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As a suggestion before putting the motor under the spanner.
Start it up, get the oil circulating, stop and let things settle. Sump plate off, let it drain down to ensure the crankcase is truly empty, sump plate back on. Disconnect Rocker feed and direct to the oil tank filler. Start up, and observe the oil return from rocker feed and the normal return flow. Ok, the rockers will be dry for a few moments of the test, but this would prove the scavenge works and the problem is oversupply to the crankcase rather than poor scavenge. Oiltank level should settle slightly, then remain constant.
The ball valve for the anti wet sumping is sealing the oilway to the timing bush when the engine is not running. So sure, no wet sumping on standing. But behind the ball is the spring and its blanking plug so when oil pressure moves the ball, this pressure is also acting on the spring plug. So a leak here feeds directly into the crankcase, and will only be apparent with engine running, and with oil pressure in the gallery. Something else to check, but awkward to do in practice, oil pump off, pump some oil into the gallery from a pressure type oil can and looking for rundown is one way.
Swarfy.
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I have found the problem thank god even tho its major. Behind the oil pump gasket the crankcase has cracked at the top return hole. The scavenge is effectively pumping some back to the tank and some back thru the crack into the bottom of the timing case. I discovered it when I was trying to change the pump.
As a temp thing and more as a test than anything I cleaned it up last night and filled the crack in with chemical metal. Tested it all today and its fine nothing out of the breather at all. I did say right at the beginning of this "War and Peace" fault that the only thing not tested was the crankcases. The crack was not noticeable at first but I think repeated loosening and tightening of the pump has actually opened the crack up. Its still only hairline but its there and if I had not decided to change the gasket for one of the one piece SRM ones I would never have found it.
I daresay the chemical metal could be used to make a permanent repair but I have spare crankcases and wont be comfortable unless I change them. Shame now I need a new main bush and line reaming all over again :(
Still at least a very baffling question has been answered.
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G'day BB.
TFFT *yeah* *yeah* *yeah*
Sort of bitter sweet outcome. As the motor gets hot the crack would open up allowing more oil to pass.
Could you post a pic of it?
Cheers
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Sort of bitter sweet outcome. As the motor gets hot the crack would open up allowing more oil to pass.
Firstly I have found it and thats the good thing. Bit upsetting that I need to strip and rebuild but it is what it is I am just thankful that I found it. I will try to post a pic when I have the crankcases apart but for some reason I have never had any joy posting pics here.
Thank you everybody for your patience with both myself and this damned problem. it has driven me to despair and I guess you have had more than enough of it as well :)
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G'day again BB.
email me any pics and I'll insert them.
Cheers
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Thank you everybody for your patience with both myself and this damned problem. it has driven me to despair and I guess you have had more than enough of it as well :)
It is when you despair that a forum like this one is invaluable. Been in that situation a couple of times myself.
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I was so happy thinking I had cured it and the damned thing still throws all its oil out once it gets hot :(
5 years off and on I have messing about with this bike (I do have other projects)
I ran it in the workshop and it got damned hot (no air flow of course) When it got hot it started pumping oil out of the breather AGAIN
Let it cool and stripped the top end off it. OVER a pint of oil in the sump????
So basically when it gets hot it is not scavenging properly.
I am gutted it was 100% oil tight and ran fantastically barring the oil problem.
I checked for wet sumping and it does not wet sump at all. A full oil tank the sump off and there is literally nothing after 3 days coming out of the sump.
I am now going to strip it completely either its the scavenge pipe cracked and the crack opening up when it gets hot or something is blocked in the crankcase.
It literally cannot be anything else
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Hi Bikerboy
I am not sure where I posted this previously so if you have already read it apologies. I had this problem and it turned out to be the oil pump not sealing/seating correctly. I am sure you have checked that but hear me out it might be worth visiting it again. I found that the washer 67-0645 between the worm pinion and the pinion gear on the crankshaft was too thick touching the body of the pump and holding it off its seating. The same thing could in theory happen if the main bearing flange is too thin or the crank its self worn positioning the crank further out towards the timing side. There is not a lot of room in that area, perhaps as it seems to happen when it gets hot and things expand two gaskets under the pump and front fixing point could be used to move the pump a bit further away from the crankcase, worth a try?
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I wonder if the problem is as simple as the return side sucks air intermittently when hot rather than oil. So, what could cause that? In that case it has got to be before the pump, and there's not much there. Pick up, crankcase wall, pump seating whatever. I just don't see anything else and that would explain all the symptoms. I'm aware this is not an answer but I wouldn't be sidetracked by anything else.
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stab in the dark because i like the dark side. have you got a powerfull sump drain plug magnet and as the oil thins with heat the magnet holds the ball down in the return pipe. ok i will go back to my beers *beer*
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I had exactly the same problem years ago with a discarded Z A7 Series crankcase. Built up a motor which ran fine until one day it started to blow smoke, eventually getting worse until the sump filled with oil, the tank emptied and contents dumped via the breather. Rebuilt, checked everything, but with the innocence of youth took heed of the do not disturb sign on the pick up pipe. Another fruitless rebuild later, same problem. Rebuilt with another set of cases, all fine.
Not to be beaten, took out that pickup pipe for a closer look, found a hairline crack in the right angle bend. Whoever was on pick up pipes in 1952 had managed to put the bare minimum of weld on the joint. Probably a good few out there like this from the same shift.
It's the top one pictured.
Swarfy.
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stab in the dark because i like the dark side. have you got a powerfull sump drain plug magnet and as the oil thins with heat the magnet holds the ball down in the return pipe
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It does not have a magnet pickup in the sump but thank you for the suggestion
I have stripped it right down and have removed the sump pick up pipe. Unfortunately it appears ok but I am going to heat it up with a blow torch tomorrow in case a crack reveals itself.
I kid you not at this point in time I am still totally baffled and I have owned and been rebuilding A10's for over 50 years. This is actually the bike I took my test on over 50 years ago (yes it had a sidecar on at the time for you legal eagles lol)
I have not done 100 miles on it since the rebuild over 5 years ago due to this problem and this and every time I think I have fixed it I put it back together and it does the same thing 10 miles later. I keep parking it up and using my other bikes until I eventually get the enthusiasm to try again.
Thanks for the suggestion on the distance washer I will check that out
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I feel for you, I really do. You seem to have covered everything, common and unusual. Do make sure you follow through the whole of the return system looking for intermittent blockage material. Rubber oil pipes have been known to have a dislodged piece that acts as a one way valve. I've had that on a petrol pipe (car). Perhaps a bit of debris somewhere? It's got to be something, however obscure.
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You seem to have covered everything, common and unusual
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Yes its totally freaky the problems I have had with this bike but I have found a place that will check and recondition the oil pump so with a bit of luck he will be able to tell me if the scavenge side of the pump is breaking down when it gets hot which should eliminate that concern.
Having said that its the 3rd pump I have fitted and one of them was tried and tested on one of my other bikes and it still got the same results
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Having said that its the 3rd pump I have fitted and one of them was tried and tested on one of my other bikes and it still got the same results
So it's not the pump! *pull hair out*
Without going back to page one. The rocker banjo bolts are correct? There some sold where the holes are too big so the oil supply overwhelms the scavenge.
Cheers
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The rocker banjo bolts are correct?
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They are right I checked them for size :(
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Reckon that another set of cases would decide this once and for all. Does the return to the tank falter as the engine warms up? If it does I would suspect a lack of scavenge. If the return remains good and strong, then it is more a measure of over supply. The crack you found may not be the only one.....there is a lot going on around that oil pump and its sealing face. Any restriction in the oil line past the rocker T off will result in increasing amounts of oil circulating directly back to the sump, coincidently accumulating the longer the engine runs and warms up. Blockages in the oil tank return pipe are rare but possible and easily checked.
Pick up pipe was originally "cemented" into the crankcase. These days Loctite does the job.
If you consider the present cases to be "scrap", and a lot spent on line boring a new bush, you have nothing to lose by simply transferring the new bush and bearings to another set of cases, chances are it will be fine. Remember the outer face of the bush needs to be an oil tight fit in the crankcase, a leak here is another source of over supply and low oil pressure.
Swarfy.
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Reckon that another set of cases would decide this once and for all
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I thought this about 2 years ago but just to let you know at no time does the oil not pump back to the tank and it does not appear to splutter at any time. The time I got it to happen in my workshop and not on the road I was alongside it watching the oil circulation none stop.
I have been keeping my eyes open on ebay and at jumbles for a set of plunger cases but so far no good. I did, yet again, blow all the oilways in the crankcase out again and no sign whatsoever of a blockage of any type. I removed the scavenge pipe and put a blowtoch on it to see if there were any cracks that opened when hot but there were not and even connecting an airline to it there is no sign whatsoever of a leak. I am sending the oil pump away for a recon and when I get it back I aim to bolt it on the case to see if there is any sign of a leak from the mating surface.
Unless I manage to pick up a set of cases I guess its rebuild again and see how it goes
Thank you everybody for your help and time
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As I am double, treble, quadrupal checking every part of this damned motor in an effort to track down why it does what it does can anybody remember the size the little holes should be in the rocker box oil banjo bolts.
I think its 1/64 but am not certain
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G'day bb.
1/64" sounds right for both inlet & exhaust sides. Apparently the SRM banjo holes are bigger *ex*
The problem with bigger holes is oversupply to the rockers and it drains down to the sump. Over 15-30 minutes that overwhelms the scavenge side of the pump and fills the crankcase to blow out the breather. Just like your problem.
Cheers
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As I am double, treble, quadrupal checking every part of this damned motor in an effort to track down why it does what it does can anybody remember the size the little holes should be in the rocker box oil banjo bolts.
I think its 1/64 but am not certain
Just a dribble of oil to the rockers on my A10, I actually think the small bore copper pipe leading to the rockers has a big if not biggest affect on flow *dunno*
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Biker Boy,
I cannot remember if I mentioned this before or not?
If there was a loose lump floating about in the return system it could restrict the return at odd times ?
I once found a lump of silicone stuck up at the top of a return pipe in the oil tank, it was right at the top where the pipe is crimped off, the only way I found it was using a lengthof inner cable, winding it up through the oil pipe
The only other suggestion, is the oil pump and its seating area flat, undamaged and level with the 3rd screw mount
I often thought that using a fibre washer at the front screw was not a good idea, who knows what thickness the washer is compared to the gasket? I make my own oil pump gaskets and extend it to the 3rd mounting
or use one of SRM's one piece gaskets
John
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I think at this point I would sit down and make a lit of every bit that has been changed and every bit that has not and look very closely at those. I number of us running old Land Rover have had really hard to find problems with the inner linings of fuel pipes becoming loose and causing restrictions leading to carb rebuilds that don't fix the fault.
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Over the years I have had banjo bolts with varying sized holes and non caused any oiling problems. The first photo is of a "Eddie Dow" rocker feed manifold and its supplied banjo bolts, see the size of the exhaust rocker hole, quite large.
Second photo shows the Webco version, which takes original pattern bolts showing smaller holes. This one been fitted to my A10 for years again no oiling problems.
Like John experience I also had a problem with an obstructed return pipe in the oil tank itself. Back over 10 years ago before I realise there was a problem, the oil tank blew its contents out of the breather during a 20 mile run.
A further problem came when the SRM end feed conversion was damaged, this caused a build up of oil in the sump which then sprayed from the breather. A new seal sorted that.
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... at no time does the oil not pump back to the tank and it does not appear to splutter at any time. The time I got it to happen in my workshop and not on the road I was alongside it watching the oil circulation none stop.
I had a long re read of this tale of woe and picked up on BB's comment above.
Maybe I'm taking you too literally but do you mean the oil return remains at a constant smooth full stream flow? i.e. we normally expect full flow from cold start after being left for a week or two then as the residual over filling of the crankcases is cleared the return starts to splutter and gout as the scavenging pump (should) always beat the supply side.
If your return stream stays a constant flow say more than two minutes in after start up then over supply, rather than poor scavenging would seem to be the issue here.
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Firstly thank you for all your suggestions and ideas regarding this P.I.T.A. problem
I decided to go back to basics and check absolutely everything.
Without the engine in the bike getting at the pipes to the tank is easy so I blew the return line out and can poke a bit of cable up it easily actually being able to see the end of the cable coming upp the return pipe in the tank. I also blocked of the return in can the tube in the tank was cracked low down, stuck at airline on it and am totally confident that there is no blockage or restriction of any kind.
Next I checked the bolts that hold the rocker box feed to the head, the flow holes in the bolts actually seem to be slightly smaller than 1/64 so I know its not getting too much oil up to the rocker box and consequently flooding the sump that way. I am unsure if I should actually drill them out to 1/64 I am still thinking on that one.
There are very few oilways in the crankcases but blew them all through thoroughly, again no sign on any restrictions. Having removed the scavenge pipe that is also clear and good. Blow one way and the ball seals blow the other and there is no restriction at all. I even heated it with a blow torch to make sure there were no cracks that I could not see that might cause the problem.
The oil pump I have sent away to be tested and I am waiting for an update on this.
The oil pump gasket is an SRM one so it does not need the washer under the pump at the front but when the pump returns I will be checking the seating of it. I aim to bolt it on the right hand case so that I can blow all the oilways when it is in situ to check that it is seating correctly.
The next stringent check will be to make sure that it in engaging correctly with the crank and the worm drive.
I have also extended the breather pipe coming out of the crankcase so that I can actually put a rubber pipe on it and wedge it into a container, just so that I dont get covered in oil again and if it does pump out I will at least be able to measure the flow coming out of the breather.
Once all these tests have been performed and hopefully passed I will bolt it back together. Should it pump oil out of the breather AGAIN I will then have a full ceremony where I will douse it in petrol and happily set the damned thing alight. *smile*
I will be purchasing a few things off Andrew at Priory, new PRV ball and spring, gaskets etc etc.
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If you can think of anything I have forgotten please shout very loudly at me *smile*
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bikerboy don't open up the banjo bolt holes i got told off for wanting to do this over 40 years ago by a chap who worked for classic mechanics. i think you should scrub out all the breather channels with little spiral brushes, i did this on worty's engine build and masses of crud came out. i also remember a piece on different timed breathers regarding the position and timing of the different holes. maybe someone could show the different timed breathers? good luck.
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Hi Berger
I did wonder if possibly I had the wrong breather part, as in the holes in a different place to what they should be. Does anybody know eactly when the breather should open as in at BDC or whenever.
All the breather spares I have the holes are in the same places so I assume they are right. Did any engine use a different breather top hat to the A10?
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Just to add to that berger every oilway, gallery etc etc has been cleaned completely including the breather route. I can honestly claim that there is no oilway that has not been blown out or had a wire or brush pushed down it to ensure it is clean and clear of any restriction
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Maybe I'm taking you too literally but do you mean the oil return remains at a constant smooth full stream flow?
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Yes I think you may be taking me a bit literally, The flow increased and decreased as I used the throttle but at no time did it stop or splutter or give any indication that flow had stopped due to the oil pump or a blocked oilway.
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bikerboy the oil return to the tank should blow a bit of air with the flow once it has scavenged any surplus from the sump on start up. i have a clear plastic line on the feed up to the rockers and always see air going up the pipe and splutters of oil into the tank, not a continuous stream .
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Hi BB,
A forum search should show posts on the breather sleeves
Something tells me that there is a difference somewhere in the gear train between the plunger and swing arm engines.
While you have the engine all apart plug up the main bush where the crank fits,
Use a pressure oil can to pump oil from the pump face hole through to the prv and crank bush. This should reveal any leakage between the bush and crankcase or at the PRV.
A hydraulic test is much better than compressed air, you would be surprised at the pressure a pump oil can can make.
Juliana post reminded me of another case
where leakage at the end feed block on a SRM converted engine made the owner and me to tear out the remining grey hairs..
I'm thinking leakage at the main bush could cause similar to Julian's and my friends Bikes symptoms?
I figured that excess oil in the timing case was carried up by the gears and flooded the breather!
Heat up your crankcase and check for leakage as above
John
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If you can think of anything I have forgotten please shout very loudly at me *smile*
The ball and spring in the crankcase to reduce wet sumping?
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The ball and spring in the crankcase to reduce wet sumping?
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Done it does not wet sump at all ever
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I'm thinking leakage at the main bush could cause similar to Julian's and my friends Bikes symptoms?
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I will check it but it was ground until it was round and then a new bush line bored as is the norm nowadays. It seems to fit fine, definitely no play for sure
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bikerboy the oil return to the tank should blow a bit of air with the flow once it has scavenged any surplus from the sump on start up
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I am aware that the scavenge is higher geared than the feed so at low revs the return does splatter a bit but over about 1000 revs its pretty consistent and has been on every A10 I have ever had. This flows as I have always known an A10 to return
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Hi BB,
I will check it but it was ground until it was round and then a new bush line bored as is the norm nowadays. It seems to fit fine, definitely no play for sure
A lot of off the shelf bushes will not be a good fit in the alloy case and leakage occurs between bush and case
(is what I was trying to say)
John
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Hi Bikerboy, A well-established member suggested for my stripdown a few years ago that I leak-test the T/S bush. It had been installed by a well-known engineering company and line-bored. I put a large rubber sleeve through the bush for sealing and immersed the crankcase half under water, and blew compressed air down the oil feed hole. Bubbles did come out from one particular spot between the bush and crankcase on one side only. Since the bush was new and had done only 80 miles I was very reluctant to replace it at huge expense. So I cleaned it with carb cleaner, dripped some Loctite 641 down the crack and ground back the surface and put some 2-pack epoxy over the offending spot. I rechecked and no bubbles. It does sound like butchery, but oil pressure was great before and after. 1000 miles later still no problem. When I told him what I had done I did not get a reply and haven't heard from him since. Seems he may not have approved. *eek* OK if you have unlimited finance!
I think if it had been leaking more severely, I would have replaced it.
Col
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Sorry I have not read all 11 pages, however, I did have a similar problem, not identical symptoms, but eventually took the bike to old mate Orabanda who pretty soon removed the oil pump, and the gasket behind it which revealed (as the photo shows if you blow it up a tad) a small score from the top left hand oil way to a gap leading back to the sump.
At idle sufficient oil was being returned to the tank to show oil returning, while the remainder was returning to the sump. Once over 40mph the oil built up in the sump and went everywhere. Just a thought from my encounter... check the base where your oil pump sits and ensure it seals. Once that offending score line was sealed... another wonderful A10 !!!
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bikerboy the oil return to the tank should blow a bit of air with the flow once it has scavenged any surplus from the sump on start up
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I am aware that the scavenge is higher geared than the feed so at low revs the return does splatter a bit but over about 1000 revs its pretty consistent and has been on every A10 I have ever had. This flows as I have always known an A10 to return
The scavenge gears are wider so pump more oil, but they turn the same speed as the pressure side.
The A65 pumps have different gears to A10, I guess longer teeth? and pump around 35% more than an A10 pump, the SRM pumps use the A65 design gears (I think….).
I have an A65 pump body and gears on my A10, with A10 drive end, so 35% extra volume at any given rpm.
I wonder if its possible to mix up A10 and A65 gears and the result is a pump that does not have the much larger scavenge capacity than the pressure side?
Another point worth emphasising is that the (gears) pretty much pump constant volume at any given rpm eg volume pumped is the same regardless of the pressure/oil viscosity etc, same goes for scavenge side so it would take a major blockage to prevent flow back to the tank, and there is no PRV in the scavenge side to limit the pressure build up if such a blockage occurred.
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The A10 and A65 gears were the same part from 1956 until 1969 according to the parts books, and had 14 teeth. There were improvements to the A65 pump by dowelling then body to nose and adding an O ring seal to the nose where the drive goes through. The last A65 pumps were iron bodied.
The photo shows the later A65 high delivery gears, much wider and with 11 teeth. The SRM pump uses the same gears.
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Just a few random thoughts...I'm baffled as well by now!!
Breather bush....Reckon the configuration and orientation of the holes is the same for all types, but Longstroke engine has the drive peg in a different place, and timing mark is different, tho' the cam gear blank is the same for all. All on the Forum, but unlikely you have the wrong gear set. Breather intake profile changed over time, later models have a shield over the bush, and so use a different part for the outer cover.
Over supply has been mentioned often enough, and we know the cases are suspect, as detailed in earlier posts. Poor seal of bush to crankcase is a real possible, see Col's experience.
Oil Pumps, plenty on the Forum. Early bikes have a "Straight Cut" to the gears, this profile changed to a more "Petal Profile" and although having the same number of teeth, do not mix. Later pumps have bigger Petals but fewer teeth, carried over to the A65 etc which shares the same basic pump body. Building up an A65 pump with A10 nose is possible but frowned upon by purists, but if you can find one with a cast iron body you get the best of both worlds at a far more economic cost....Julian got there first with a little more detail.
Oilways, don't forget the one that leads from PRV blow off to cam trough. This is not found on early engines, which vent into the oil pump cavity.
Swarfy.
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G'day BB.
Again without going back to page 1.
The steel end plate of the pump can/does over time become worn from the gears trying to mill their way through. This reduces the scavenge sides capacity to pump.
Whenever I have a pump apart I lap the end plate and extension housing on a piece of glass to remove the marks.
Cheers
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regarding everything that has been said about this engine chucking oil out of the breather i know these engines run with flat cam lobes, convex followers , 2 inch of piston slap , well maybe ;) super pocketed valve seats . snapped cranks!!!!!! as in mine in 1980 did , mine present day with 10thou difference in piston heights after getting the big end eye round again after some pillock had shaved a cap years ago and she still hits 7000rpm when i'm on one! in worty's case an eighth of an inch play in the timing side bush --- not quite but might as well have been , a loose oil pump and for gods sake a million more horrors that i found and worty's didn't chuck oil out when it got hot, in fact it's a wonder it didn't blow itself up!!!! if you read worty's engine strip on this forum you will wonder what the hell is going on with this engine that makes it chuck oil out when it gets hot and worty's horror didn't !!!. send it to me i NEED to know why?
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worty's horror engine, ball bearing in cam oil hole , how the hell did that get there?? my snapped crank , worty's idler bush loosened because of the crank dancing about like a northern soul geeza on powder. i wish i could find or not deleted more photos of the loose oil pump and as i say it didn't chuck oil out it relied on the big ends being splash fed because of a lack of pressure and the shells took the strain and luckily not the journals. so what is going on with that engine chucking oil out when worty's should have been the engine throwing oil out -- regarding feed and return flows ??????? and look how much worty's crank had danced about! i am baffled by your problem but i need to know WHY!?
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A lot of off the shelf bushes will not be a good fit in the alloy case and leakage occurs between bush and case
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Oh my bad I misinterpreted what you meant that is definitely worth a check
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I put a large rubber sleeve through the bush for sealing and immersed the crankcase half under water, and blew compressed air down the oil feed hole. Bubbles did come out from one particular spot between the bush and crankcase on one side only
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Highlighting what chaterlea said and well worth a check
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Hi Gavin
I can see what you said and thought the last time I had stripped it that I had found a crack in the crack case behind the pump and not on the sealing surface. Unfortunately when stripped it was not cracked (my mistake) it was just a bit of a score that was no problem the sealing surfaces are fine although I am going to check them for flat before it goes together again.
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Oilways, don't forget the one that leads from PRV blow off to cam trough
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Mine does go to just above the oil pump a tiny hole in the crankcase. I have blown it out and it appears fine but I did wonder if maybe my PRV spring was weak therefore oil going straight thru into that oilway in turn filling up the timing case. I have already swapped the PRV with one of my other A10's so think its unlikely but I am going to change the ball and spring in the PRV anyway.
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Again without going back to page 1.
The steel end plate of the pump can/does over time become worn from the gears trying to mill their way through. This reduces the scavenge sides capacity to pump.
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Hi muskrat there was nothing apparent wrong with the pump thats why I have sent it to be tested as their test rig is bound to give better results than me inspecting it by eye.
Thanks to all of you for your suggestions I do take them all seriously
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Hi BB,
The oilway as you said his up to the timing gears, But also continues to the rear of the engine then right angles along parallel to the camshaft.. there is a drilling from the cam trough into this passage, which has an alloy plug pressed in at the crankcase half joint.. it is this passageway that takes the bulk of the oil that is bypassed by the PRV.
John
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Oilways, don't forget the one that leads from PRV blow off to cam trough
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Mine does go to just above the oil pump a tiny hole in the crankcase. I have blown it out and it appears fine but I did wonder if maybe my PRV spring was weak therefore oil going straight thru into that oilway in turn filling up the timing case. I have already swapped the PRV with one of my other A10's so think its unlikely but I am going to change the ball and spring in the PRV anyway.
As per my prior post the pump will pretty much pump the same volume regardless of resistance (and consequent pressure) so a weak PRV will make little difference to volume pumped.
99% the issue is on the scavenge side, where pressure is minimal.
I do realise given the circumstances everything has to be checked…..
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The oilway as you said his up to the timing gears, But also continues to the rear of the engine then right angles along parallel to the camshaft
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Many thanks after all these years I did not know that the oilway continued on to the cam trough. Now I do and I checked and it is all clear :!
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As per my prior post the pump will pretty much pump the same volume regardless of resistance (and consequent pressure) so a weak PRV will make little difference to volume pumped.
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I tend to agree no matter how much is pumped into the sump then the scavenge if working properly should be able to deal with it. I would have stuck with that thought until this damned engine and now I am beginning to wonder.
Having so many bikes does not help I thought this still had old pistons in it but when I stripped it the ones in there are new.
Still confused and still waiting on a verdict regarding the oil pump
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Right I resume the saga of the plunger A10 *sad2*
Oil pumps back from testing (I sent two off) apparently they were both working absolutely fine.
Scavenge feed removed and checked out, blow one way and it seals blow the other and it is as clear as a bell. All oilways blown out and where possible something poked thru to check they are all clear. I did think of taking the sludge trap back out for a look but cant see the point. IMO the problem must be on the scavenge side so if any feed pipes were blocked then the sump would not fill up anyway.
Poked a bit of 14/030 cable up the scavenge pipes to see if there was any obstruction all seems clear.
I have extended the breather pipe from the crankcase so that at least I can get a tube on it and save myself coating the back end of the bike in oil again. I was thinking of putting a tube on the breather and taking it to a clear bottle of some type so that I can keep my eye on it while I try it.
Any other suggestions before I bolt it together AGAIN?
If it still pumps out oil I will put it back in the garage for a year or two as I have enough other projects that are not driving me insane to get on with. Meanwhile I will keep my eyes open at the jumbles for a set of plunger crankcases purely because I cannot think of anything else that it might be.
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Somewhere in the previous posts mention was made of the pistons and bores. Poor sealing of the rings is a recipe for blow by and crankcase compression,(though whether this would cause a continuous flow of oil from the breather) and could be a contributing factor. My earlier thoughts on the pick up pipe hold true, it gave me the same symptoms. If the motor is built up again and still plays up, try it without the tappet covers. With no crankcase pressure (and normal oil return) that would point to the problem being related to the pistons rather than the lubrication system.
Pass me another straw to clutch......
Swarfy.
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Poor sealing of the rings is a recipe for blow by and crankcase compression
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I agree and I am going to take the pistons and the bore in to be measured up but if the bores or rings were faulty I would expect the cylinder head to show signs of burning any oil that got past the rings. The inlet valves are the perfect straw colour with the exhaust valves being a fair bit darker which is exactly what a lovely cylinder head and valves should look like. I will add it does not smoke AT ALL even when oil is pumping out of the breather. Compression test is fine, new pistons and a relined bore. I do have a leakdown tester which I will put on it but I will be honest I find it hard to believe its the bore.
Thanks for your suggestion tho because sooner or later this fault will be exposed I am just gutted it has taken so damned long *sad2*
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i went to the pub *countdown* breather timing or cork not working , these engines running with one ring wouldn't chuck oil out of the breather as you describe it. send it to me down the river on a biscuit and hope it floats ;) now there's a thing a re lined bore with sleeves - maybe the problem , gaps and spacers hit and miss liners? ok i am going to bed *countdown* *help*
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Well I had quite a detailed chat to Andrew of Priory Magnetos to get some spares. We came to the conclusion that either the gauze plate in the sump is not letting enough oil back from the crankcases or too much oil is going up to the rocker box which slowly filles the sump up. Its about all that is left. I aim to punch a couple of big holes in the sump gauze before I put it back on and if it cures it then I can just replace the gauze with a new one. If that fails I aim to block the rocker feed and see what happens, I have a blanked of breather in the rocker cover so I can squirt a bit of oil in there ever mile of so to make sure its lubed up ok.
If that fails I will change the crankcases next.
Fingers crossed *sad2*
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Well I had quite a detailed chat to Andrew of Priory Magnetos to get some spares. We came to the conclusion that either the gauze plate in the sump is not letting enough oil back from the crankcases or too much oil is going up to the rocker box which slowly filles the sump up. Its about all that is left. I aim to punch a couple of big holes in the sump gauze before I put it back on and if it cures it then I can just replace the gauze with a new one. If that fails I aim to block the rocker feed and see what happens, I have a blanked of breather in the rocker cover so I can squirt a bit of oil in there ever mile of so to make sure its lubed up ok.
If that fails I will change the crankcases next.
Fingers crossed *sad2*
Sorry if this has been mentioned but there are 12 pages of comments 🤔 and I’ve not read them all….but I was doing an oil change today and whilst waiting for the tank to drain it occurred to me that the oil tank breather/tower could cause mayhem if blocked or restricted as the return flow would pressurise it, and maybe force more oil up to the rockers, possibly also cause the flow side to increase in volume….maybe via the non return ball/spring *dunno*
Simple check would be to go for a ride with filler cap removed.
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Well, well, well I appear to have cured the damned problem and the answer was just ridiculous.
I wont take all the credit mind. I phoned Andrew at Priory for some bits and pieces to rebuild the engine YET AGAIN and we had a somewhat detailed chat about things. We decided two things, it was either pumping too much oil to the rockers OR it was not getting the oil out of the sump quickly enough and therefore the sump was filling up bit by bit as I rode until it pumped out of the breather.
I said to Andrew that I had checked the sump gauze and was not happy that oil could get through it quickly enough. Basically I held the gauze over a container and pumped some oil on to it from my oil can. I could actually count to 6 quite slowly before the oil actually starting dripping through the gauze. As a test I decided to leave the gauze off for test purposes.
Well I left it off and rigged up a container to catch any oil that did come out of the breather as I am sick to death of being covered in oil. After doing 20 miles, with my eye one the container all the way, there was no oil whatsoever coming out of the breather or any sign of any oil in the tube coming from the breather. *smile* *smile* *smile*
The bike run perfectly and as it used to start pumping out after about 7 or 8 miles I am actually confident that I have cured the damned problem.
Yes the gauze was brand new, yes it looked ok, so its yet another big sign that some pattern parts are pure crap.
Thank you so much for everybody who showed an interest and attempted to help with some great suggestions but I am actually confident this time that the problem has been found.
5 years trying to track down a stupid problem caused by a stupid bit of wire bloody gauze.
Before anybody thinks I spent 5 years non stop on this I never I do have quite a few bikes so kept pushing this one to the back of the garage with pure frustration *conf*
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bikerboy *yeah* *yeah* sometimes problems are so difficult but yet so easy, rate pleased for you *beer*
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Can you post a picture of the gauze?
It would be interesting to know what is actually wrong with it.
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The offending item
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That's really interesting. At first sight the gauze looks OK but I suspect the wire size is too big to while the pitch looks right the gaps are too small. Almost impossible to notice.
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Strange stuff. Looks like a gauze that would work OK.
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Just looked at images of the original A10 set up. The gauze is a top hat shape soldered into the cover. That means it has quite a bit more area with the sides as well as the top. All the replacements are flat but as you have proved, its not the same. If you fit a return filter you could probably do without the gauze. Mine has a replacement flat gauze so I will be watching this closely.
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I can think of two possibilities: the wire pin in the pickup pipe is missing, meaning the anti-drain ball can go right up and block the pipe, or the sump gauze is too fine and oil can't drain through it fast enough to get to the return suction pipe.
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Going through this thread I just noticed this comment from RDfella
Seems like he was right and as the gauze was brand new I sort of glossed over it. Well done RD shame I obviously discounted the possibility.
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G'day BB.
Great to hear you found the culprit. *yeah*
Strange as I have those fitted to both my A's. The Cafe breather is plumbed back to the oil tank but the A7 is standard and never had that problem. I can't remember where I got mine from but could it be that different manufacturers use different gauze ? Mine do look like yours.
Cheers
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Just looked at images of the original A10 set up. The gauze is a top hat shape soldered into the cover. That means it has quite a bit more area with the sides as well as the top. All the replacements are flat but as you have proved, its not the same. If you fit a return filter you could probably do without the gauze. Mine has a replacement flat gauze so I will be watching this closely.
I think this gauze is to protect the scavenge side of the pump from big particles? (rather than the bigger job of keeping the oil clean).
My bike has this gauze, I guess there are some finer than others *dunno*
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I agree its to protect the pump from bits, but if the engine is creating bits like that you have bigger problems. With a return filter everything should be getting taken out by that so it can't come round again and there's the pick up filter in the tank too. I do think its worth having the sump gauze in for the first few runs after a rebuild, no matter how careful there always seems to be a lump of Hylomar that finds its way to the bottom.
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The ones I use and sell have 'SRM' embossed around the edge.
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It's great that you've got it fixed. Theoretically, if the sump plate is properly sealed against the bottom of the crankcase, the return suction pipe should cause a vacuum in the void where the oil usually collects, sufficient to draw the oil through the gauze. This leads me to wonder whether the sump was sealed properly and maybe the suction pipe was drawing air instead. Whatever!....It would appear to be something to do with the gauze plate.
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wow, what an interesting issue and long drawnout solution!!
I have been looking to fit a sump plate with a magnetic drain plug for sometime, just never got around to it. However, I would like to do that and have been looking at a few different styles, is there a particular version that fits without any modifications and works best (I have noted some with flat gauzes ie minimum volume under the gauze and wondered if thats a good idea, maybe the suction tube can sit too close to the bottom flat face for example??
maybe useful thoughts to close out this thread..
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I have tapped my steel sump plate 3/8 BSC and used the drain plug 82-5343 with a Dowty washer. In the past I have made magnetic sump plugs by drilling and pressing in a neodymium magnet but I've only found them useful on gearboxes where they will catch a tooth chip and stop it doing more damage. In the engine its mostly, if not all, non-ferrous.
I did spend quite a bit of time adjusting the pick up and gauze to get a good fit between the pipe and the hole but I'm not sure its possible to get any form of seal.
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I did spend quite a bit of time adjusting the pick up and gauze to get a good fit between the pipe and the hole but I'm not sure its possible to get any form of seal.
If the gauze is domed or raised, like the thing below, the oil level might never reach the hole, so a seal might not be important.
(https://i.postimg.cc/j5QhRHCn/IMG-0859.jpg)
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That is the original design and I think it is better. My gauze was missing and I couldn't find a solder in replacement, only flat plates. This discussion has got me thinking whether its possible to buy some flat gauze and make one. I've been making patrol tap filters from brass gauze and its gone better than expected.
Someone has old stock correct sump plates and gauze on e-bay but they are £35!
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Good to know yet another facet of this syndrome has been revealed. I'm considering the viscosity of stone cold oil and whether on start up the residual oil coating on small mesh is enough to cause the blockage. But all through this saga I'm sure the oil return has been accepted as closer to expected normal than otherwise.
As far as lubrication goes, early post indicates Straight 40. Would anyone consider a modern synthetic low viscosity oil eg 5W30 as being suitable? I know thin oil is a recipe for wet sumping, but this stuff is used on car engines with more stress than our motors.
Rob's picture shows support wires within the dome. These domes come in various forms, I've seen one which is made from sheet, with small holes punched. Not one I would risk. The dome offers a greater surface area for filtration over the flat plate, which looks to be not such a good idea.
Swarfy
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I've done a web search and here are pictures of a new original part 41-620 and a quality flat replacement. Its hard to be sure but I think the original part is a more open mesh.
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my biggest concern with the flat plate is the lack of clearance between the pipe end and the plate....
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Hi All,
Asking the question?
What brand and grade of oil is BB using?
There are some brands of "classic" oils on the market that are not suitable for our BSA bikes
As far as I can find out they are 're constituted blends? So have "heavy" additives which can form a thick slimey coating that clogs up gauze screens etc.
Swarfcut ? Asked about using modern multi grade oils in our BSA's,
As far as I know these do not have the zinc additive needed for cam/tappet lubrication as in BSA engines.
Attached pic of a sludged up tank filter that resulted in a main bush seizure *eek*
I only use Castrol 40 in the BSA's and their 20/50 in the MG
John
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That is horrifying and should not be possible. I've put a 20/50 from Smith and Allen in the BSA and Matchless, I buy it in bulk and use it in the 1970 Land Rover too. My other thought was a straight 40 mineral oil. After seeing your piture I will be keeping a very close watch on flow and sludge.
https://www.smithandallan.com/product/smith-allan-ultra-20w-50-mineral-engine-oil-3986
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Hi All,
Asking the question?
What brand and grade of oil is BB using?
There are some brands of "classic" oils on the market that are not suitable for our BSA bikes
As far as I can find out they are 're constituted blends? So have "heavy" additives which can form a thick slimey coating that clogs up gauze screens etc.
Swarfcut ? Asked about using modern multi grade oils in our BSA's,
As far as I know these do not have the zinc additive needed for cam/tappet lubrication as in BSA engines.
Attached pic of a sludged up tank filter that resulted in a main bush seizure *eek*
(https://i.postimg.cc/0NxS9qB9/IMG-0865.png)
I only use Castrol 40 in the BSA's and their 20/50 in the MG
John
Goodness! How long did that sludge take to build up? Were oil changes neglected?
I change oil (synthetic 20W/50) and paper element filter annually, which is around 2,000 miles. I can see the gauze, through the tank filler neck and no sludge builds up on it at all. The wire mesh is shiny.
There is a small amount of settled-out black stuff on the bottom of the tank. I’ve cleaned it once in 32 years.
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Hi TT and All,
I rebuilt the bike approx 10 years before it was sold on to the current owner, it had covered only about 4k miles in that time. The owner was well experienced in old bikes and I very much doubt such "goo" could accumulate if the Castrol 40 I put in it oil had not been changed.. I have other anecdotal stories where these oils have gummed up crankcase pickup meshes resulting in wet sumping.
John
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Chipping in with my experience. I fitted one of the modern flat screens in the sump along with a ally sump plate, fitted an external filter, serviced the anti-wetsump valve in the crankcase.
I bought a 25ltr drum of Morris's SAE40 oil and changed the bikes oil frequently. Over 10 years, no oil problems.
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What brand and grade of oil is BB using?
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I am using Moris straight 40 like I do in all my A10's. The oil on that A10 was changed about every 20 minutes or so *smile*
On a great note I have road tested the bike 3 times now every ride was over 20 miles and my emergency oil container from the breather does not have a drop in it *smile*
I think i can remove that and declare the bike fixed.
BTW it rides fantastically and I am super super pleased.
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Well 1400 miles later and no problems I think its fixed for sure.
It was running with no strainer in the sump so I took the sump off and fitted one of my old standard sumps with strainer and it appears fine.
I was well pleased because altho it had not been started for 8 weeks when I dropped the sump there was possibly half a cup of oil in there so it does not wet sump at all as well.
Thanks again to everybody that commented and tried to help, this forum really is invaluable even to seasoned A10 owners, despite how much you experience you have there is still lots to learn from the people on this forum
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*yeah* *yeah* *grins*
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Swarfcut ? Asked about using modern multi grade oils in our BSA's,
As far as I know these do not have the zinc additive needed for cam/tappet lubrication as in BSA engines.
Attached pic of a sludged up tank filter that resulted in a main bush seizure *eek*
I only use Castrol 40 in the BSA's and their 20/50 in the MG
John
John,
I realize this is an old post already, but curious. Does the Castrol 40 have the added ZDDP (zinc)? I'm using Valvoline VR1 20/50 Recing Oil rated for push rods and flat tappets. Not sure it's street legal, but who's tasting (mmm, that's delicious!) https://shop.valvolineglobal.com/collections/vr1-racing-motor-oil/products/vr1-racing-motor-oil-sae-20w-50?bvstate=pg:2/ct:r&utm_source=google-ads&utm_medium=cpc&utm_campaign=DTC_DSA_Racing-Oil&utm_agid=155129418909&utm_term=&creative=680461325921&device=c&placement=&gad_source=1&gclid=CjwKCAjw5qC2BhB8EiwAvqa41nc8O6H2BVFitdEnTOlvGGVAgHZrfEitOiq4k1nODxQDcQltKgVDCBoCo3AQAvD_BwE
Richard L.
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I am using Valvoline VR1 20-50 in 2 A10s and an A7 for about 5 years and am now using the "new" formula, all good so far. As I understand it oil with high zinc and other additives in "racing" oil are not suitable for road vehicles because they can damage catalytic converters and thus avoid claims against themselves. It is of course necessary in our old bikes for the extreme pressure at the cam and follower
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Hi Richard and All,
Yes the Castrol "Classic" range has the needed zinc and additives that are needed for "flat tappets" and the likes
John
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I am using Valvoline VR1 20-50
In my post about the VR1 racing oil I slipped and called it Mobil. Fixed now
Richard L.