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Exhaust in valve covers?

RammaR

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'96 XLT 4x4
I've had a good size oil leak from both valve covers on my '96 4.0 ohv engine. A little over a year ago I replaced the heads on the engine and used new rubber gaskets. So when I pulled the covers today, I was a little surprised at what I found. I had 6 oil leaks - once at each exhaust valve / manifold. see the attached pictures:

cover1.jpg


gasket1.jpg


You can see on the lower side of the gasket where it's blackened above each exhaust manifold joint / below the exhaust valve and allowed oil to leak. My first thought was that exhaust gases were blowing past the seal at the valve, but now I'm starting to think it's just the heat of the exhaust manifold that melted the gasket material.

Any thoughts or suggestions? Has anyone seen this before? It's doing it directly above where the exhaust manifold connects on all 6 cylinders. It takes awhile to pull off both valve covers, so if there is an issue, I'd rather fix it now than do it all over again in a few months.

Thanks!
 






SoNic67

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2001 V8 (Eddie Bauer) AWD
Before you did pull those covers off, did you try to remove the oil fill cap? Did it exhaust "smoke"? Do you have oil "spitted" past the oil dipstick? All those would mean that exhaust gases "escape" past one or more rings.
Also, the gasket might be overheated if you had exhaust "leaking" hot gases by the gaskets - but you would have to see the same burns in the manifold gasket, no?
 






RammaR

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Good suggestions on removing the caps - didn't suspect anything like that so I never pulled them with the engine running. Will check it out once its back together tomorrow.

Still seems strange that all 6 ports are doing it, not just one or two. The upper intake gasket looked perfect, the only dark / burnt gasket is the bottom side of the valve covers. In fact, the top side directly opposite the dark marks look fine.

I'm thinking of putting it back with some high temp rtv right in those areas to help seal / protect the gaskets. But would really like to know the cause.

Thanks.
 






SoNic67

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If the rings are worn, you will be able to feel a fairly strong pressure "pulsation" (related to engine rpm) when you cover the oil fill hole with your palm.
 






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