Thread: Help - Oil overflowing

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Hey guys,

I have a 1978 T-Bird, with a 351 Windsor.

My question is: What would cause oil to overflow out of my vented oil cap? It doesnt fly out of the cap, but I can see that some oil got onto the valve cover.

Hopefully this is enough info. Thanks a lot for your help!

Originally posted by elbatrop1
Hey guys,

I have a 1978 T-Bird, with a 351 Windsor.

My question is: What would cause oil to overflow out of my vented oil cap? It doesnt fly out of the cap, but I can see that some oil got onto the valve cover.

Hopefully this is enough info. Thanks a lot for your help!

Could have a blown gasket. Could have excessive blow by. Could be as simple as needing a new PCV valve.

thanks for a place to start

I read into it a little more, and I checked my crankcase vacuum at my oil cap. Then I checked the vacuum from the manifold (with the PCV valve still attached to the hose) and I was shocked cuz the valve damn near sucked my finger in

Would this be a PCV valve problem?

A plugged oil return hole in the head will fill your valve cover with oil.

Pull the valve covers and use a coat hanger to unplug the oil returns in the heads.... common old ford problem when the oil wasn't changed regularly...
on your pcv problem its probally related as it most likely that it has sludge built up in it also, holding the valve in it open..
also beware that after you disturb all that sludge that will be built up on the top of the heads that you will most likely have to pull the oil pan and clean that and the oil pickup screen,might as well put a new oil pump in it wihile your there.......

Or it could be that you have cheap aftermarket valve covers that don't have a baffle under the cap. The rocker arms fling a lot of oil around under there and a baffle minimizes the "escape" of the oil droplets. Btw, there are baffled grommets that sometimes help.