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post #1 of (permalink) Old 09-10-2001, 07:16 PM
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Oil In Air Cleaner of 4.0 L

I just picked up (cheap) a 1993 YJ 4.0 (fuel injected) Auto, with 115K on it. Oil is blowing into the Air cleaner. I cleaned out the CCV (like a PVC) valve and installed a clean line to the manifold thinking that the vacuum was blocked but I am still getting oil in the air cleaner. Any thoughts?


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post #2 of (permalink) Old 09-10-2001, 08:04 PM
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Re: Oil In Air Cleaner of 4.0 L

do a compression test on it.. sounds like your rings are bad.. you can get a tester at like autozone.. they loan/rent these out.. test the compression.. should be about 150psi.. probably have one or more cylinders low.. around 120-130 range.. if so.. then squirt some oil into those low cylinders.. and retest them.. if it jumps up to 150+ then those cylinders have bad rings in them.. this is a common problem with any old engine..
what happens is as your engine runs.. the compression inside the cylinders gets passed by the rings.. and down into the crank case (oil pan).. as oil is pumped thru the engine.. (to the top) it should drain back to the oil pan.. but due to the bypassed gases that are in the crank case.. it now has a higher pressure than the rest of the engine.. so oil will take the path of least resistance.. ie.. out that unblocked hose and into your air cleaner..
for a temporary fix.. unplug it from you air cleaner.. and run it into a container.. ie. gatorade bottle.. when full dump out... just keep oil in the engine.. (this trick also works for when you blow out a rear main seal.. )


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post #3 of (permalink) Old 09-10-2001, 08:25 PM
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Re: Oil In Air Cleaner of 4.0 L

Jeepgod is right, but if you run that line into a Gatorade bottle you'll be breathing fumes all day long. The problem is that the oil comes out of the valve cover in a vapor form, and it enters the bottle. Sure, some may settle and form a puddle, but for the most part my experience has been a cabin full of oil smell from the fumes all over the engine bay. You'll have to rig up something a little more elaborate than just a tube to a bottle to avoid the fumes.

Another idea which helped me some was to slightly enlarge the hole at the entrace to the CCV tube on the valve cover end. Allows it to suck in a little more fumes into the manifold.

Good luck.

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post #4 of (permalink) Old 09-10-2001, 08:44 PM
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Re: Oil In Air Cleaner of 4.0 L

Thanks Guys- That was my guess but I was hoping that there was a trick that I didn't know about that would keep me from have to rebuild the motor for awhile. I'll do the compression test to make sure.

Thanks Again!

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