Distributor + oil leak =

[rob650]

Thanks in advance for any assistance

I took off my front engine cover and discovered evidence of an oil leak out of the bottom of my (distributor? - silver can gizmo directly below my alternator).  

is this a common problem?
Sign of something nastier that I should be looking for?  
Can be remedied with a new O-ring? (according to MAXBMW parts diagram) and is that a straightforward job?

70K miles.  No operating problems otherwise.

[Bob_Roller]

You just need to replace the o-ring on the ignition canister .

Mark the engine case and the canister, so you get it back on and probably not have to mess with the ignition timing .

[georgesgiralt]

Hello !
There are two gaskets here. The obvious outside O-ring (which may well be the culprit) and a concealed gasket in the body of the can preventing oil to enter the can by sealing the axis of rotation of the device.
If the oil is leaking inside the can, this one is the culprit and you are dead because it is not possible to change it being below a soldered plate... And difficult to see, if you dismantle the unit you will just see it's lip (very fragile, do not disturb).

[rob650]

Thanks George and Bob, ill order the new o-ring, and mark the distributor so i can reinstall it in the exact same position.

[Barry]

Georges is correct the O ring only seals the exterior of the can.  On my points type can the shaft seal is some sort of mechanical seal made up of various discs as shown top right on this picture from ADVrider.

[georgesgiralt]

Not only, Barry, if you look into the can after removing everything, you'll see that the internal bottom is actually a plate of a different metal than the can. Underneath is the gasket I speak of. As this plate is sealed, there is no chance replacing the gasket.

[Barry]

Georges,  

Is this gasket some sort of lip seal. I don't remember seeing that on my bean can but I could be mistaken as it's 5 years since I had mine apart and It's also possible the points can and electronic can are different. The bean can was based on a Volkswagen distributor and perhaps didn't need such good oil control in that application.

I must admit that a proper lip seal is just what the bean can needs. I found  a little oil in my bean can when I first got the bike. I knew it was nothing to do with the O ring and just assumed the shaft seal was a little crude as the problem seemed to largely disappear on it's own. I did nothing except take the bean can apart and put it back together. I still have a little oil mist in there but it's not a problem and at least lubricates the advance mechanism.

I wonder if this problem is a symptom of excessive crankcase compression ?

 

[georgesgiralt]

Yes, it is a lip seal. I found the spring floating around the shaft when I opened my bean can so make me wonder. And after careful inspection I found it. Alas, I was unable to put the spring back nor replace the seal...