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post #1 of (permalink) Old 05-22-2010, 01:47 PM Thread Starter
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Question 4.0 valve cover help

I have a 1991 Cherokee Laredo that has the popular oil in air filter problem. After reading threads on here and purchasing the hoses mentioned i installed them and still oil in air filtler. Now after reading more threads on here I've come to the conclusion that I need a new valve cover to fix the clogged built in pcv valve. My question is will a 1993 valve cover fit on it? I've searched the web and am not having luck finding one for my '91.
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post #2 of (permalink) Old 05-31-2010, 08:26 AM
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To my knowledge they are the same. Did you consider cleaning the valves? It's no rocketscience. I cut some new gaskets from a piece of gasketpaper. But you should wonder why they get dirty. It sounds as if you have quite some blowby. Did the engine overheat 1 or 2 times? Are the rings worn? Did you test the vaccuum on the thin line?

If the oil is a sign of a worn engine, replacing the cover won't help much.


If in doubt, add a bit more

Jamboree '94 stock 4.0 AX15 8.25
Cherokee Pioneer '88 i6 2-door 5 speed mostly stock put asleep
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post #3 of (permalink) Old 08-18-2014, 09:23 PM
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My 88 XJ with the 4.0 has had the same problem. We found it when tearing the top end down to replace the head gasket. The valve cover had a layer of sludge covering the inside of it. We cleaned the cover with Purple Clean, as with all other internals. Under the head the pistons and all were pretty clean. The engine had been fully rebuilt, including bored .030 over, not that many miles ago. We ditched the stock air box for a homemade cold air set up. There is one of those small valve cover breathers in the big hole. I now have oil coming out of that and covering the engine and burning on the exhaust where it crosses under the engine.
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