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Valve Cover Clarification

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I've seen a fair amount of talk on here recently about the steel vs. aluminum valve covers and I just wanted to clarify a few things I was unsure of.


I can visually recognize the difference between them from looking in the engine compartment... My '92 4.0 MJ has the aluminum one and my '01 4.0 XJ has the newer steel one found on the '97+ models. My first question involves the baffles inside the cover that everyone talks about. Since both motors are HO models does the aluminum cover on the MJ still have the baffles?


What are the advantages/disadvantages of performing the swap to the newer style steel valve cover on my '92 MJ? Will I need any additional or different hardware or is it a direct swap?


Pardon my ignorance on this subject, but I was interested in making the mod and wanted to get my facts straight before pursuing it further. Thanks.

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The aluminum cover does have baffles but are located only just below the breathers and not the entire length of the cover...


Advantages/disadantages? well the cork gasket for your '92 is alot cheaper than the rubber gasket for the '01...also supposedly valvetrain noise is less noticeable with the aluminum cover...


As far as I can see....it is a direct swap....the two covers just use different gaskets and breather grommets.

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I put a steel valve cover from a '96 on my '90 in an effort to reduce the amount of oil dumping into the air filter. The '96 (and newer I assume) has a one piece baffle that runs the entire length of the cover. It reduced the oil by about 50% but didn't stop it entirely.

If you don't have blow by soaking the air filter there's probably no advantage to swapping valve covers. But, since I'm on the subject, What else can I do to reduce the amount of oil dumping in my air filter?

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So just to get this straight... The only real advantage to the newer steel valve cover is the baffles running the full length of it which help eliminate any blow-by getting to the air filter.


I do have some blow-by getting to the air filter... not alot, but enough to annoy me. From what I've read here and in other posts, the valve cover swap is usually at least somewhat succesful in eliminating this problem.


I'm not real impressed with the cork gasket either. Granted, my XJ doesn't have nearly as many miles as the MJ, but I don't notice oil saturating the gasket and seeping through on the gasket on the XJ like I see on the MJ. I replaced the valve cover gasket on the MJ probably about 4 years ago and it already has gotten saturated.

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