Interesting Oil Seep btwn Tranny & Engine

[losangelesR90]

Been a while since I've posted here. New forum it appears as I had to re-register my login.
Hope everything has been well. Imagine many of the same folks are hanging out here.


Got my 1976 R90 running again after pulling it from storage.
A new battery fixed my starting problem and the bike is running great & strong.

Engine was fairly dirty on the back end around the tranny and airbox (last major ride was the SoCal TT, ~600 miles in 2 days) so I pulled the airbox and and noticed the breather hose was no longer on the breather itself. Oil was definitely coming out of the breather into the airbox/starter area and the cause of all the grime. Removed the starter cover, cleaned out most the oild and put the hose back on the breather with a hose clamp to secure it.

Washed the bike and ran it a good 15 miles or so to do an oil/filter change. Upon return home, I noticed an interesting "oil seep" around the seam between tranny and engine.

First thought was rear main seal, but I always thought the sign of that was oil pooling on top of the oil pan below the tranny. That area seems pretty dry. Hoping that is not the case as I'm planning on riding the ~600 mile TT again Sunday-Monday.

So then I thought maybe the breather hose was off for a while and oil went down into the flywheel/clutch area and is now being flush outward when the bike runs..

Thoughts??

Took a few photos to share..

Best,
Erik Hillard
1976 BMW R90 S'd
Los Angeles

[ME 109]

Flung off the flywheel would be my guess.

[losangelesR90]

Thanks. Appears my gut is likely correct. Going to ride on and wipe it off as it comes out. Definitely seems like old oil at this point and not the fresh clean stuff currently in the bike.

[Kurt in S.A.]

Clean oil mixing with dirty oil residue and abraded clutch particles??

Kurt in S.A.

[Motorhead]

After my first BMW that had the wrong rings that lasted 1500 before major oil use oil habits similer to whats going on

I decided to use a R65 breather cover and plumb into 1977 R100RS clamb shell airfilter set up with Cold Charge holes which has a 2 inlet for the oil rich crank spacer breather to dump into both carbs


Didn't you use a aftermarket Nicsil kit in this bike

When is the Ride I'd like to be posted for the Hanson dam ride GOOD to hear for you Erik

Lyman

[Jay.T]

I have the same issue with a 93 PD. My guess is the input shaft on the gearbox. I also think it is being flung off the input shaft of the gearbox. The other spot I think it could be is the output from the engine. If it where the ouput shaft seal, by the time it worked its way all the way down to get flung off at the opposite end, it would have also be flung on to the clutch. I do not have any clutch slippage. I have bought the input shaft seal, $10, going to install in a couple of weeks. I will update my findings. This leak on my bike has been there for a couple of thousand miles with no other problems than unsightly oil so it has not been a top priority. A few other items first.

[losangelesR90]

I'm pretty sure the oil is leftover from the breather leak when the hose was unattached for a while. Ran the bike for just under 600 miles on the TT and there is a bit more but not much. Will do another clean of the bike and go out and run it hard again. But pretty much no oil usage on the 600 mile ride so I'm thinking all is good.

[losangelesR90]

Didn't you use a aftermarket Nicsil kit in this bike

I put in the Siebenrock 1000cc upgrade kit..

http://www.eurotechmotorsports.com/form ... StartRow=1