I assumed that my oil seepage was a return of the clogged flame trap problem that I had temporarily fixed with the motor flush trick in the FAQ.

I just replaced everything in the vent system last weekend with new parts- from the block up to the flame trap. Very nice.

The pressure problem is still there! I'm worried about eventually blowing a seal.

What could the over-pressure problem be caused by?

I did replace that narrow hose from the flame trap, and used the straw from a can of WD-40 to poke out the crud in the manifold fitting; I felt a little pop from the manifold end so something (a partial obstruction?) came loose.

The thing is, the oil filler cap when unscrewed with the engine running, sits there rattling around madly --there is no decent suction holding it down. I take this as a bad sign.

That test of the cap staying in place at idle was valid for the heavier metal caps used by Volvo some time ago.

A better test of a slight vacuum in the crankcase is to use your hand or a piece of paper.

Randy

Try a new rubber O-ring for the oil cap. Mine was rock hard and shrunken. FCP for like 1$.

Did you drill out the brass fitting were the hose attaches to the intake manifold? It gets plugged with a hard carbonlike material.

Will do.

Mine (1990 745T, auto, 209k miles, towing package, by my lights) also seeps oil at the filler cap. Was leaving it alone, figuring pressure exiting there would damage less than it would elsewhere. Now I will look at this hose on my car, Thank you.