'Yellow' oil from crankcase vent pipe.
 

Can anyone help.

In the crank case vent pipe that fits onto the air filter housing, there is some yellow oil residue (we're talking a bright golden yellow!), as well as oil fumes that increase when the engine is reved.

I thought it may be water getting into the engine, but there is no residue on the oil filler cap and no sludge in the water expansion tank which I though were the normal placed to look

Any ideas????


'88 560SEC 176,000 miles

Try pulling out the crankcase dipstick to see if the same residue or foam is seen there.

Water can go into the oil without the reverse taking place (oil in the water).

Ken300D

Aside from the unusual color, it appears that at 176,000 miles, your engine may be suffering from "blowby", in which gases from combustion escape from the cylinders due to worn cylinder bores and/or worn or cracked piston rings, pressurize the oil sump and escape (with a small quantity of engine oil) via the route you discussed.