Boxerworks.com

As I was troubleshooting my ignition/timing problem, I finally got my bike going again and saw a bunch of oil leaking from my oil filter cover. I drained all the oil, replaced the filter, o ring, washer and seal. Started the bike up, and it is leaking from the exact same place. It seems to be around 7 o'clock if you are looking at the cover straight on.

It's a R100CS engine (1980). Any ideas what I can do to stop/prevent this?

Everything was cleaned up and reassembled ok.

It leaks when the engine is running (due to oil pressure). Not when sitting.

Dang, it's like whack-a-mole with this bike lately. Once I fix an issue, another pops up.

-JJ

Did you do the last oil/filter change? Condition of O ring and shim?

When you say "seal", do you mean the gasket?
I'm assuming this motor has just the larger white gasket with the recessed cover... no cooler.
It's my understanding you need to measure the depth that the washer sits at to make sure the o-ring has proper compression.

http://largiader.com/tech/filters/

I thought with those white o-rings, you don't use the paper gasket because it reduces the compression of the o-ring.
I could be wrong about it, but I don't use the gasket on my 77RS. or on my 94 Mystic that has a cooler and uses both the white o-ring and the black squared o-ring. I do use the gasket on the 75 R90S I care-take, as it has the inner cap and the flat cover.

When I first bought my Mystic, I took it to a dealer for a once-over. They changed the oil and filter. Afterwards, it had a slight leak from the filter. When I took the cover off the filter, I found they didn't seat the white o-ring properly. I've done all my own service since then.

I have the recessed cover - no cooler.
And it uses the white O ring, and thin silver washer, and the black paper gasket.

I'm going to try to lean the bike over to the side and go through it again. I will probably need a new gasket to be safe. I don't want to have to drain the oil again.... It's just odd that it happened in the first place, and then again with all new materials.

Be certain you install the shim in the correct order.

Yes, shim goes in first then the o-ring. On my /7, the canister is only 2.8mm below the surface of the case. For me, I need to use the paper gasket otherwise the o-ring gets way too much compression. Definitely measure the canister depth. If the canister depth is well over 3.5mm, you'll need an extra shim.

Kurt in S.A.

This depth determines the amount of space that the O-ring will occupy when the cover is installed. Different mechanics shim the O-ring differently, but they generally leave between 3.2mm and 3.8mm for the O-ring, which is 4mm thick uncompressed. Using a cover gasket increases the space by 0.45mm, and using a shim decreases the space by 0.3mm.
From Largiader

Regardless whether you have a gasket on the cover or not, If oil leaks from the cover then the white O ring isn't sealing and you will risk damage due to low oil pressure if you run it.

Think of the gasket as no more than a spacer to be used or not according to the canister depth calculations. Even without a gasket there should be no leak from the cover if the white O ring is being adequately compressed.

Aaaah. The shim was against the cover, vs in the engine before the white O ring. It was how it was when I took it apart and had nearly 1000 miles on it in that orientation. So I assembled it the same way.
I will lean the bike over with the help of an unsuspecting neighbor, reverse the two so the shim goes in first, and then use a new gasket. Hopefully that solves it.

Is the o-ring brand new? Inspect for cuts just in case. Don't use a new gasket until you know if you need to or not. Measure the canister depth and go from there. The gasket does not seal against leaks as previously explained. In this instance, it is a spacer. The gasket is a must use on the pre /7 engines with a completely different oil filter configuration.

Kurt in S.A.