P11 Oil leak from points cover

I have had my P11 for 20 years and enjoyed a reliable 20,000 + miles on it. It has however recently started leaking oil from the points housing (behind the cylinders). It became so bad that I was forced to strip the timing side out remove the housing and try to find the reason. I noted an oil drain hole which might be allowing oil in from the timing case (it has electronic ignition). I blocked this, rebuilt, no change. I stripped down again, removed the housing, took apart the back plate and replaced the internal paper gasket between the back plate and the points housing (not the paper one between the housing and the timing cover, which I change every time anyway) even though it looked fine, rebuilt, no change. I stripped it all down again, and this time changed the sealed roller bearing, even though I could not see a problem with the seals, rebuilt, guess what? still no change. Am now at a bit of a loss now to know how or where oil could possibly be getting into this housing. Has anyone else had this problem? Thoughts appreciated.

Are you sure the leak originates from the points housing? Considering its location, the ingress of oil from the timing cover should be virtually zero. My hunch tells me your rocker feed line could be the culprit ....

-Knut

It's a good point Knut, but fraid not. I can actually watch it drip out of the housing cover cable hole and after about a mile riding and it 1/4 fills the cover!

Oil level in the timing cover must be way too high. When did you last replace the oil pump seal (NMT272) and the Crankshaft oil seal (NMT 2124) ?

- Knut

I did replace the oil pump seal on the first time I stripped the housing out, but have to say... I did not think about the crankshaft oil seal. I think you must be right, but even if it is getting too full, it should not be able to get into the points housing, unless the pressure is so great from the timing side? Sounding like a major job.

How does your engine breath?

And are you sure it’s breathing freely?

Excess crankcase pressure will force oil out of many a seemingly unlikely place.

jonsug said:

I did replace the oil pump seal on the first time I stripped the housing out, but have to say... I did not think about the crankshaft oil seal. I think you must be right, but even if it is getting too full, it should not be able to get into the points housing, unless the pressure is so great from the timing side? Sounding like a major job.

Click to expand...

Replacing the crankshaft seal is a simple job, once the timing cover is off. The seal is secured by a circlip. If the seal is compromised, your timing cover could fill up to a level above the drain hole, especially if crankcase pressure is high.

- Knut

mdt-son said:

Replacing the crankshaft seal is a simple job, once the timing cover is off. The seal is secured by a circlip. If the seal is compromised, your timing cover could fill up to a level above the drain hole, especially if crankcase pressure is high.

- Knut

Click to expand...

I think you must be right, I will whip off that cover again and replace. Thanks for your help with this, I'll let you know how it goes.

Fast Eddie said:

How does your engine breath?

And are you sure it’s breathing freely?

Excess crankcase pressure will force oil out of many a seemingly unlikely place.

Click to expand...

good point, but I have a 8mm ID main crankcase breather normally placed in front of the barrels on the Primary side, calculated length based on the cylinder sweep, so it should breath OK and I just looked and can't see a kink in it.

Hi , sorry for delay in coming back to this issue, have been away, but just to let you guys know I replaced the crankshaft oil seal and alas no change, oil still fast dripping out of the ignition housing. I can only assume, now I have replaced all gaskets and oil seals in the timing side, that maybe the oil pressure release valve is stuck? if so I guess the pressure would build up in the timing cover particularly when cold and potentially blow through the timing shaft sealed bearing and the housing gasket? would that seem like a possible/likely cause? The OPRV is really tight on, I tried to remove before with the casing off without success but can get some leverage on it now its on the engine without risk of damage to the faces. Thoughts appreciated.

good point, but I have a 8mm ID main crankcase breather normally placed in front of the barrels on the Primary side, calculated length based on the cylinder sweep, so it should breath OK and I just looked and can't see a kink in it.