Oil in air filter

Curious, I have a 1987 XJ with a 4.0...... Changed my air filter today and half of it was coated with oil. Any input on why this happened....or is it normal?

I becomes normal with miles. The cure is to remove the valve cover and clean out the "snorkel" fittings.

In addition to the VC cleaning, probably replace or clean the CCV harness & hoses. Your 87 likely has some miles and this is a 'routine' 60-80k? replacement item.

There was a tech service bulliten (TSB) issued Oct 1991 (No. 14-51-91) for this problem. The TSB says to replace the small tube that runs from the rear of the valve cover to the intake manifold. The solution is to buy the new part which includes a new grommet.

On our 4.0 engine there is not a classic PCV system; instead, there is continuous crankcase ventilation (CCV) system. There is not PCV valve you can shake and make sure it rattles. The small tube I talked about has an orfice to provide a constant leak.

Also on the valve cover is a large tube connected to the front portion. This tube runs from the air fiter box to the valve cover. This tube provides filtered air to the crankcase. This item is sold in two pieces, so you have to buy both halves.

The problem you have occurs when the little tube becomes stopped up. If that happens then the only place for pressure inside the engine can exit is the large tube. That is why you see oil on your air filter.

In the owner's manual it says the CCV tubes are to be replaced ever 50,000 miles along with the gas cap, spark plug wire, distributror cap & rotor.

If your XJ was like mine when I took possion in 1997 all these tubes are OEM. I had to break the rubber fitting on the large tube to get it out of the valve cover.

My first recommendation is to go to the dealer and buy all 3 pieces. Expect to spend the better part of a $100 bill for these parts.

If you have oil on your valve cover then pick up a oil filler cap, I paid less than $3 at the dealer for my last one. I'd also pick up a new gas tank cap.

I would install all those new parts, then turn the air filter around in the box and drive it for a week or two. After that time then check the air filter to see if their is oil on it. If the filter is "dry" then you have the problem solved. Just remember to change those CCV tubes every 50K miles.

There are write ups about cleaning out the vavle cover, I did that to my XJ and did not change much. My valve cover did have some carbon on the snorkels but overall was clean.

If it still is dripping oil then I would take the XJ to the muffler shop and have them change the cat coverter. This is a lesson I learned on my own. If the cat is partially stopped up the exhaust system will provice a back pressure. It was not until I had the cat changed did this oil in the filter problem finally disappear.

So plan on spending $70 to $100 for the CCV tube and $150-$200 for a new cat installed a the local muffler shop.

Hope that helps, here an article I followed when I cleaned my valve cover http://www.off-road.com/jeep/cherokee/xjtech/engine/40ltr/blowby.htm

Adding to what Martin wrote, the newer vacuum line has a different set of elbows from the original, with gentler curves. It shouldn't make much difference, but it does. The system seems to be very delicately balanced. The combination of sharp curves and "arterial plaque" inside the lines is critical.

I can't recall where I found it, but if you remove the ccv valve (rear one) and drill out the hole to 1/8' or a little larger it will help also. when you do that make sure you clean the valve and the tubes. I did this before I changed engines and it fixed the problem for the two months I drove it before the engine was replaced with a '97
hth