[micco]

Hi!
I was changing motor oil yesterday to R1100RS '98 when I noticed that old oil flows out very slowly. I opened the oil fill cap and oil comes out normally. The breather is completelly blocked. It doesn't breath at all when engine is running.

 

[micco]

micco, does your bike behave like mine, soaking your feet in oil as you ride it? With my bike parked at idle speed, I can feel puffs of air with my hand, blowing past the valve cover gasket. At highway speed this air under pressure carries along a lot of crankcase oil.

The owner of the bike burned clutch 6 months ago and it hasn't been ridden since. I replaced the clutch and was doing maintenance when I noticed blocked breather. There are no signs of oil leaks anyway.
I opened the front cover but it was waste of time. Nothing to see there.
I also used compressed air to blow to breather pipe. Nothing goes through.
Then I installed front cover back to engine and blowed some pressure to engine through oil fill port. Nothing comes out from breather.

 

[micco]

R1100 engine has two rear main seals and crankcase pressure should flow between them. In this case the outer seal was pushed so deep inside it blocked air passage.

 

[micco]