B31 - bad oil leak from Primary drive cover

[Fraz]

Hello.
I'm new to this malarkey and my new B31(1954) Plunger is dripping oil from the "primary drive cover" (if that's the right name?)

When the engine runs, it dumps loads of oil out of the same place (the lowest point of the cover)

I've removed the cover and about 1.5 pints of oil came out.

There's a cork gasket attached to the cover with Hermatite, leading me to believe that the cover should "seal" the area and hold oil?
Is this true?

How much oil should be behind the cover?
Should it be gasket sealed so it doesn't leak?
Where does the oil come from?
New gasket time?

Many thanks

[rhyatt]

if your bike has been standing a while, then the oil from the oil tank may have dribbled down through the oil pump into the sump - filled that up and then dribbled through the drive side main bearing into the primary chaincase. then onto the floor !!!!!

the cover when assembled should be about 1/8th pint(but others will tell you if I am wrong on the quantity)

basically - use the bike regularly or leave the sump plug out and re-cycle the oil dribbling down back into the oil tank

[Greenfield]

The first question I would ask is what are the levels of engine oil in the tank ? Was the primary drive overfilled or is it receiving engine oil/gearbox oil?
Are you leaving the bike on it's sidestand allowing oil to drain into the primary case?
Before you fit a new gasket made sure there are no distortions due to overtightening? If the faces are good, a smear of grease on the cork surfaces should be enough to seal. Don't overtighten. Remember to replace the felt and cork washers as well.
With the bike level, just add enough oil for the primary chain to pick up oil during running. Take out the spark plug, put it in top gear and turn the back wheel while you add oil through the inspection cover. You'll see when it start to pick up some oil.

[Fraz]

The first question I would ask is what are the levels of engine oil in the tank ? Was the primary drive overfilled or is it receiving engine oil/gearbox oil?
Are you leaving the bike on it's sidestand allowing oil to drain into the primary case?
Before you fit a new gasket made sure there are no distortions due to overtightening? If the faces are good, a smear of grease on the cork surfaces should be enough to seal. Don't overtighten. Remember to replace the felt and cork washers as well.
With the bike level, just add enough oil for the primary chain to pick up oil during running. Take out the spark plug, put it in top gear and turn the back wheel while you add oil through the inspection cover. You'll see when it start to pick up some oil.

Thanks for your reply.

The bike had been standing since 2016
I dropped the stop plug and the engine oil tank and filled it to correct levels in the tank.
Unfortunately, I don't have a side stand (I didn't know the B31 could have one - I've beta blessing if it could)

I've not found any felt or cork washers, only the cork gasket around the lip of the cover.

[Derek996]

I doubt if a side stand would make any difference. By time oil is leaking past the drive side main bearings the crankcase will be nearly half full anyway.

[Fraz]

I doubt if a side stand would make any difference. By time oil is leaking past the drive side main bearings the crankcase will be nearly half full anyway.

Do you know how much oil should be inside the primary drive chain cover?
Just a splash or up to the filling hole?

And should the gasket hold the oil?

Thanks

[rhyatt]

They're usually about 1/8th pint , but someone suggested earlier sensibly to put a small amount in and then run the engine and add a tiny bit until the primary chain just flicks the oil around.
Yes the gasket should hold the oil in there, but again someone else has recommended to ensure there are no deformation between the inner and outer chain cases.
The screws will pull the 2 halves together , but ensure they're a decent mechanical fit in the first place.

[Rog1]

I've not found any felt or cork washers, only the cork gasket around the lip of the cover.

There should be a cork washer at either end of the distance piece for the footrest bar, and a felt washer behind the sliding plate that sits behind the clutch. The two cork washers are both the same; part number 66-4902. The felt washer is part 15-8814. The cork gasket for the primary case cover, by the way, is part 66-7514.

[Fraz]

They're usually about 1/8th pint , but someone suggested earlier sensibly to put a small amount in and then run the engine and add a tiny bit until the primary chain just flicks the oil around.
Yes the gasket should hold the oil in there, but again someone else has recommended to ensure there are no deformation between the inner and outer chain cases.
The screws will pull the 2 halves together , but ensure they're a decent mechanical fit in the first place.

Thanks, a job for the weekend

[WayneBergman]

I have a 1952 B33. Leaks oil from all the usuall places. For what its worth I will share here what seems to be working for me for a solution......
When I drained all the oil out of the primary when I rebuilt the gearbox and clutch I decided not to put any oil back into the primary at all. I figure how much oil does an enclosed chain really need anyways. Depending on how much I ride it I will put the machine up on its center stand and start it up, let er run in first gear with the rear wheel off the ground spinning, then with a tooth brush I dip the brush into the motors oil tank (running the same 50 weight oil as normally used for the primary and engine) and then I open the little round inspection cover on the primary cover and lube the chain with the tooth brush. I do this about every 2oo miles and all seems to be good. I am no mechanic and also a bit lazy so always looking for the short cuts. I may be way off base on this one but I feel this is all that is needed. Hope this helps..........wayne