I'm not an auto engineer so that why the question mark in the Subject line.

I have the bleedin' infamous leaking oil cap on my '89 745T. Seal is fine; tangs have been bent over on cap for better fit, PCV hose to turbo is clear and blowing through renders little pressure loss.

But a few things to consider. Is blowing through the PCV line (w/ oil cap off) a good way to test? When the car is running oil is being pumped up and then gravity draining to sump. How is excessive pressure supposed to be relieved when the return lines are full of oil (for that matter, how do so much pressure get up there, considering it should have an easier route via oil separator to PCV and back into turbo intake).

One of my projects in new year is to take the valve cover off and machine the surface flat where gasket contacts. Mine has scrapes on it and I believe these are deep enough to allow oil to pass through them and onto valve cover. And being the anal-retentive chowder head I am, I DON'T LIKE oil on my valve cover.

But I realize machining the surface is not solving the problem of excessive pressure at the oil cap seal. Back to original query though. Why did Volvo choose to have one source for a PCV on a high compression turbo engine? Even my wimpy Honda has a PCV valve inline from valve cover to intake manifold PLUS a line to air cleaner housing via oil separator.

I guess what the Volvo engineers decided was decided. I just want to stop this excessive pressure yet I can't understand how to do it will current setup. And no Big Harry, I'm not hacking holes in my valve cover!

Thanks for your time.
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Norm Cook; Vancouver BC; 1989 745T 210,000KM