zebvance

I have a 1988 mj 4.0. It has a about 103,000 miles. I drove it for about 1500 miles on the highway and beach and noticed oil pouring out of the air box from time to time. It was getting into the air box through the two small hoses the the rear of the air box. The side closest to the firewall. Well I did my reasearch and the attempted to fix it by replacing the valve cover, and all the CCv hoseing with new and replacing the plugs in the top of the valve cover too because I read that they could be clogged and this is what prob caused the blow by. Well I did all that and drove for about 400 high way and beach miles and it got way worst. It's almost as if those hoses being clogged helped it from pouring out on to the air box. Just pulled the air filter which has about 1800 miles on it because i am pulling the intake and everything off to put a header and motor mounts on and it is absolutely soaked and drinched in oil. I mean the whole thing is black.

So my next thought is the rings are gone....? Well that just seems hard to believe, only having 100,000 miles. Also the exhaust does not somke at all! On even one bit on start up. Just 100% clean dry exhaust. Also when the valve cover was off the rockers and everything looked in very good shape and there was no sludge build up. The truck runs great besides this. No knocking lots of power, no ticking, nothing.

So I guess I have come to the conclusion that there is nothing I can do about the blow by besides controlling it from pouring out of my air box and all over my shock, spring an down the whole driver side under carrige.

So how do I do this? I have looked at oil catch cans but it looks like the inlet and out let are to big for the hoses that are pulling the oil into the air box.

All help and advise is needed!

TheJerm

To check the condition of the motor, since the gauge might be wrong or something else is an issue, check the compression in each cylinder to see if in fact there are worn rings causing blow by

My heap has 230K hard miles and after replacing the head, clean 99+ intake and header, I was really mad when the blow by gummed up everything in short order. I made a oil catch out of a soup can, piece of beer can, duct tape, some heater hose, random pipe and t-fitting with some JB weld putty stuff to seal the fittings. I go snap some pics of it installed. works great.

zebvance

What year is yours and I would be interested in what lines you ran to the catch can.

TheJerm

Mines a 95 and was made with stuff laying around. Forgot to look but think its 3/4" heater hose i used that fits snugly over crankcase vents. Having issues with phone so have to wait to plug into my home computer to upload pics

TheJerm

Just noticed the Advance tech thread on this, posting pics over there to consolidate all the info for future people

tjwalker

You must perform a compression test. Good data = good decisions. Don't assume you can't have an issue with the rings just because of lower mileage.

Perform a dry test. Then if any cylinders are low, perform a wet test with a tablespoon of oil introduced into the cylinder. The compression spec for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders. If you have a low cylinder and the pressure comes up with oil introduced, you have a ring issue.

You can rent a compression gauge inexpensively at many parts stores if you don't have one or have access to one.

Let us know the exact numbers.

zebvance

Im not familiar with compression testing. If you don't mind me asking what is the procedure to do so.

tjwalker

Google it. Lots and lots of good articles that cover "automotive compression test".

DFlintstone

In my signature there is a valve cover mod by cruiser54 you might want to read