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what causes oil to come up into the oil cap while the engine is running? the engine is in a 1970 stang. 302, 2V, c-4 trans. i have a pcv valve in the right valve cover and a push-in ford motorsports oil cap in the left. the oil cap has a place to put a hose that would go to the air cleaner, if my air cleaner had a place to connect it. right now i don't have a hose on it. it is blowing enough oil to make me mad on my chrome valve covers. what would cause this or what do i need to do? any ideas...

My chrome valve covers both have baffles. I know that the oil cap needs some kind of vent in it, because I have tested that already. With the oil cap just plugged, I get some oil blowing out the dipstick tube. This leads me to believe that I probably have worn rings. I did a compression check and all cylinders checked good and strong. I don't get much oil blown out the cap, just blows a little out on the valve cover which P's me off. The oil cap I have is hollow. Maybe if I stuff something in there that will allow the engine to breath, but won't let the little bit of oil blow out. I think that if I run a hose to the air cleaner, it will just blow the oil up there, which I don't want either.

10,588 Posts
This question looks familiar..*G*

I'll assume you've verified the operation of the PCV valve (that it sucks)...

You might wish to do a leakdown test to determine where and how bad your blow-by is. Then, you can decide what to do next.

Although I have little blow-by on the race car and don't run PCV, I do handle oiling problems like you describe by running seperators on the valve covers with a hose going to a puke tank. Engine remains dry as a bone after years of on-and-off operation.

Most of your trouble would go away if you hooked up a hose to the air cleaner'd get some oil in there but at least it would be contained and more easily cleaned.

What were your cranking compression readings with the engine warm and no oil added to the cylinders?
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