Oil leak through the air filter

I have a 88 4.0 litre that likes to leak oil through the air filter. I had a guy tell me that is was blocked somewhere and I should flush it with diesel once or twice and that should help it out, but a buddy of mine said it would completley de-lube the bearings and everything and I don't want to do that is there any other way to like flush the oil system out? Please help I have oil all over the engine compartment and it is no fun. It has about 144000 on it. It also sat for about 3 years.

How many miles on your XJ? Also, a 1/2 quart of diesel run thru at IDLE for about 20 minutes will not hurt anything since diesel is oil based. It sounds like you may have a case of blow-by and the pressure is venting out where it can. The diesel will help to clean the inside of the motor, but if it is blow-by I think other people will speak up and offer advice on how to deal with this. I just ran two hoses from the top of my valve cover down to the pass. side of the engine bay, down by the charcoal can, and stuck the hoses in the frame rail to keep the oil somewhat out of the engine bay.

88bluecrunched said:

I have a 88 4.0 litre that likes to leak oil through the air filter. I had a guy tell me that is was blocked somewhere and I should flush it with diesel once or twice and that should help it out, but a buddy of mine said it would completley de-lube the bearings and everything and I don't want to do that is there any other way to like flush the oil system out? Please help I have oil all over the engine compartment and it is no fun. It has about 144000 on it. It also sat for about 3 years.

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PCV system isn't working very well, common with high mileage XJs.
Read this article:
http://www.off-road.com/jeep/cherokee/98/04_apr/valvecover/cover.html
and this one:
http://www.off-road.com/jeep/cherokee/xjtech/engine/40ltr/blowby.htm

This is called blow-by and stated before. I had the same problem on my '88. There can be many culprits. First, clean out the rear CCV tube, with a paper clip or drill bit. YOu might replace it too or do the MAD-XJ update on it. http://www.madxj.com/
You can clean the valve cover and get new lines. This didn't cure my problem. I got a good seal on the valve cover to head with RTV. A leaking VC disrupts the balance of air flow and then lets the air intake such oil out of the engine.
Tom