Gas mixes with oil, and blows through inlet

[Tobi09]

But how is it even possible that oil is blowing out of the inlet? What is the mechanism? In my view this could only happen if the inlet valve is defective. Or how do you see it?

I had a similar problem. Mower was not used for a while, needle of the carb let gas through, found its way into the oil, raising oil level significantly over the highest mark (was not checked before starting) and the oil blew out of the air inlet into the air filter. Replacing the oil to a normal level made the engine run "ok" again.

 

[bertsmobile1]

The engine breathes through the air filter so the oily fumes get sucked back into the carb and burned.
Same thing happens with your car.

The oher mechanism is there is a decompression system that is only supposed to work when the engine is at cranking speeds which bleeds off some of the charge backwards into the manifold & carb where s in the old das was bleed off into the exhaust