Baffled, confused and covered in oil!!!!!!

[duTch]

 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 .....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.....

[RDfella]

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.

[JulianS]

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.

[RDfella]

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.

[bikerboy]

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

[edboy]

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.

[RDfella]

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.

[bikerboy]

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 :)

[BigJim]

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.

[KiwiGF]

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.

[Swarfcut]

 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.

[bikerboy]

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.

[KiwiGF]

Im disappointed  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......

[Swarfcut]

 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.

[beezermacc]

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!