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post #1 of (permalink) Old 03-12-2005, 10:53 AM
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oil in my airfilter box

Hope somebody has an idea on this one because I'm stumped. My '89 YJ has the 2.5L engine and lately I have been having a problem with oil being blown back into the aircleaner through the vent tube that runs from the valve cover into the aircleaner box.

This only seems to happen when I have been doing some extended highway driving. If I am just running around town or out on the trails it doesn't appear to be happening, but if I go on the freeway for around 10 miles or more (more rev's) I will find oil in the bottom of the aircleaner box.

The engine has about 118K on it, but it seems to run strong and there is never any evidence of smoke coming out of the tail pipe. The pcv valve seemed to be working fine, but I replaced it anyway just in case. No difference. If I pull the breather tube out of the valve cover and hold a thumb over it while revving the engine, it doesn't feel like there is any pressure there.

I'm stumped and getting kind of tired of coming home from a run and having my Jeep bleed all over everything. Anybody got any ideas?
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post #2 of (permalink) Old 03-12-2005, 01:37 PM
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Re: oil in my airfilter box

You've probably got more blowby at highway speeds that the PCV valve can handle. Try a new PCV valve. If that doesn't cure it, run a compression test. It might be that you'll have to live with it or rebuild the engine.

I had that problem once and made a manifold that allowed me to put two PCV valves in parallel. That helped some but didn't cure it.
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post #3 of (permalink) Old 03-12-2005, 02:52 PM
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Re: oil in my airfilter box

This subject has been beat to death and lots of info can be found on here, if you are patient. Our search function is having some problems.

Personally, I've had great luck with blow-by by adding an oil additive called Restore.
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post #4 of (permalink) Old 03-13-2005, 06:00 PM
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Re: oil in my airfilter box

You're right, I wasn't patient. My first search returned a lot of threads that were'nt what I was looking for and I didn't feel like "waiting" until I could do another search. I'll try to be more patient.

Meanwhile, I have borrowed a compression tester from a friend and I will be checking the cylinders this week. I have replaced the PCV valve and that made no difference.

I am also thinking about creating a "catch can" to run the vent hose into. THis would allow me to avoid the oil all over my air filter and leaking out of the box until I can pull the engine out (if that's what it needs). Any thoughts on that idea?
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