Perhaps someone can give the benefit of their technical knowledge, I have recently discovered air being pushed out of the gasket under the rocker cover on my 110 2.5D. I have ordered a new gasket to replace the old grotty one, but a number of people I have mentioned this to have expressed surprise that I have air pressure inside the rocker cover at all. I have tried removing the breather tube from the oil filer cap, and sure enough there is air being pumped out of the filler cap as the engine idles. This seems strange given that there is a filter inside the cap which would indicate to me that air is supposed to flow into the rocker cover not out. Frightening phrases such as 'crank case over pressure' and 'piston replacement' have also been mentioned, so my questions are:
Should air be blown out of the rocker cover or sucked in?
If it should be sucked in why is mine being blown out and how do I fix this?
In trepidation...
Smudge