Author Topic: wet sumping  (Read 5329 times)

Offline broom34

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wet sumping
« on: 03.01. 2011 20:05 »
Hi
      Can anyone tell me why my A10 is wet sumping ,I know most A10's wet sump but why, and what actually is going wrong, and more to the point how to rectify this problem .After all they're not made to wet sump when coming from the factory ,so what's going wrong .and how do we solve this problem without fitting a non return valve or having to kick start the bike everyday, or fitting a new oil pump, which would be to costly, so whats the answer?

Richard

Online bsa-bill

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Re: wet sumping
« Reply #1 on: 03.01. 2011 20:30 »
There are two non return valves already in an A10.
One in the sump to stop oil returning from the scavenging side of the pump
One behind the pump to keep the pump primed
Obviously the one in the sump is the first to suspect, also some oil will drain down after the engine stops.

Normally it's not a big problem as an A10/7 used regularly as they were intended will clear any surplus oil from the sump without the rider ever knowing it was there.
The problem can happen if the bike is not used for some time, then it's possible that there is more oil in the sump then the pump can clear quickly and excess will be ejected via the engine breather behind the crankcase.

neither of my A10s wet sump even though they are left for long periods in the winter without starting but then they have both had engine rebiulds.
I did have an A10 in the sixties that did wet sump once but there were mitigating circumstances a/ it had stood for about three weeks idle and b/ the rider had no knowledge of maintenance including oil changes
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online trevinoz

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Re: wet sumping
« Reply #2 on: 03.01. 2011 20:37 »
Richard,
                This problem has been well discussed over the years.
Basically the problem is the gear pump and gravity.The gears in the pump have clearance between them and their housings and the head of oil in the tank will force oil through this clearance.
There is a check valve fitted behind the delivery port in the crankcase but it is not accessible unless the cases are split.
You may find that the check ball could use reseating after many tears of use and a new spring would not go astray.
Also you may find oil leaking from the pump body as there are no gaskets or seals.
Mostly we just live with it.
This problem is not exclusive to BSA.
Nortons had the problem for years until a check valve was fitted in the timing cover of the late 850s.
Ask Matchless and AJS owners about it also.
Trev.

Offline Goldy

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Re: wet sumping
« Reply #3 on: 03.01. 2011 20:46 »
Richard. You will find lots of discussion about wet sumping on previous pages of this forum it creats quite a talking point. The answer is very very simple. The oil either drains down through the non return valve or through the worn oil pump. I had wet sumping, even after stripping and cleaning the non return valve. I therefore fitted a drain plug to the sump plate by welding in a threaded boss. The idea was to remove the drain plug prior to starting the machine and so drain the oil prior to starting the bike. Although it is a simple job it turned out to be a pain, having to do this every time I started the bike, So I bought a new SRM oil pump and I have never had wet sumping since. All the best
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Online trevinoz

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Re: wet sumping
« Reply #4 on: 03.01. 2011 20:54 »
I think some of you gents are a bit confused about the non return valve in the scavenge pipe.
The only oil that can find its way back into the sump via this valve is that which is in the return line.
The oil in the tank cannot be siphoned back to the sump as the return outlet in the oil tank is higher than the oil level.
There is not enough oil in the return circuit to fill the sump.
Trev.

Online bsa-bill

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Re: wet sumping
« Reply #5 on: 03.01. 2011 21:18 »
Good point Trevor although those of us with filters will have a bit more available *smiley4*

I like to mention the two non return valves (I recall someone listing four once) just remind those who decry the Bri-Tie valve as dangerous  *evil*
But each to his own opinion of course
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

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Re: wet sumping
« Reply #6 on: 03.01. 2011 21:36 »
Bill,
         The in line automatic feed line valve IS dangerous!
I have seen what happens to a Commando engine when it fails to operate!
If the oil between said valve and the pump drains away, the valve will not open.
Trev.

Offline rocket man

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Re: wet sumping
« Reply #7 on: 03.01. 2011 21:47 »
fit an srm sump kit it has a drain plug with magnet on a very good idea


dave

Offline LJ.

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Re: wet sumping
« Reply #8 on: 03.01. 2011 21:57 »
A lot to be said for the straight 50 thick oil here. I use this in all my engines and wet sumping is not a problem. I have also heard mention that if when you switch off engine you leave the pistons at top dead centre, this also helps stop wet sumping? any truth in that?
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

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Re: wet sumping
« Reply #9 on: 03.01. 2011 22:07 »
I've heard that too LJ can't recall the reason but I think it made sense
Trevor I hear what you say but my mate and I both used the valves for years without trouble, would think pump condition has bearing

I have the kits on both my A's Dave, matter of fact the last one came from CCM ( I think ) made for B? something but fits A's
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline 1660bob

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Re: wet sumping
« Reply #10 on: 04.01. 2011 09:20 »
Trev, good point about the return line only having a small amount of oil in it-obvious when you stop to think.That leads me to wonder what is the purpose of the valve in the first place- i assume it is simply to keep the scavenge side primed so that it works from the off when the bike is started? Bob.

Offline muskrat

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Re: wet sumping
« Reply #11 on: 04.01. 2011 09:55 »
Yep, all said and done. A worn pump and or an iffy NRV behind the pump. Both my A's do it. Drain plug fitted, empty sump before ride takes 3 minutes.
I would prefer to leave crank at BDC so oil stays in the crank so big ends get oil right from the start.
Cheers
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Offline Mark Parker

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Re: wet sumping
« Reply #12 on: 04.01. 2011 10:48 »
I know with an A65 pump they can leak where the main body joins the front section even with the screws tight, oil goes directly into the timing case and sump, so no oil needs to seep past gears or past the little ball valve particularly, just seeps out the side, and may be the reason a new SRM pump can cure it. It's easy to see with the T/cover off, just wipe the side of the pump then come back in 15 minutes and look for oil at the joint. Seeping there is probably fixable with a lot of fiddling, it's only the feed side that needs working on, as has been pointed out it cannot wetsump through the scavenge side, though I guess oil from the feed side may be able to seep along the shafts in the pump into the scavenge pump area.
Mark
Had a nice A10 once, :( now only have the power egg child A65 :(

Offline nigeldtr

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Re: wet sumping
« Reply #13 on: 04.01. 2011 16:24 »
I have a spare death valve that I have taken of a recently purchased A1O. The oil emptied itself into the sum in about 3 days. Now fitted an SRM pump, external pressure gauge and am in the process or fitting external oil filter. The old pump looks in good condition and I think the real problem was the fact that the chap had used a fibre washer on the stud near the worm drive and a thinner paper gasket under the pump body so I suspect the oil was pouring out around the base of the pump only found this out when I stripped it (fortunately, the main bearing has no excessive play). Also, one of the studs was very tight in the pump body so may also have stopped the pump sitting flat on the face.

Not fired the bike back up yet, want to clean the oil tank and fit and external filter first. (hope the valve behind the pump is doing its job *smi *smile*le*)

Regards

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Offline BSA_54A10

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Re: wet sumping
« Reply #14 on: 05.01. 2011 07:23 »
Quote
After all they're not made to wet sump when coming from the factory ,so what's going wrong
We are.
From new they were designed to be used as daily transport, that meant firing it up at least twice every day if not 4 or 6 times.
When used this way very few wet sump, clutches don't stick & carb slides don't gall .
When used every second Sunday, only if it is a fine day lack of use problems manifest themselves.

Best solution is to fit a sump with a magnetic drain plug.
Every time you get home, before you even take your hat off, drain the oil from both the tank & sump.
Put the plugs on the tank to remind you that the bike has no oil.
The oil will be clean enough to be collected and put into your 4 wheeler and the oil in your engine will always be nice and fresh so you will end up getting 2 to 3 times the life out of your bottom end for the cost of about £ 200/ pa as comparred to £ 1000 + for a rebuild.
Bike Beesa
Trevor