Hello All,

I was recently given a 1990 Cherokee. It runs well (about 174,000 miles), but it leaks a LOT of oil when running. The Jeep was given to someone else who gave it to me. The intermediary took it to a mechanic who said that excessive crankcase pressure from a worn engine was causing the engine to leak from the front and rear main seals and the valve cover gaskets. He suggested a new engine, but after doing some research, I think there might be some hope.

I plan to remove the valve covers, clean everything out, and replace the CCV valve fittings and hoses to reduce crankcase pressure. Then I will replace the seals. I need some advice, though. I've found the parts and a write up that describes replacing the rear main seal, but I haven't found any write ups or any "front main seal" on the O'Reilly Autoparts website. Any thoughts? Could it be the "crankcase seal," or something completely different? Also, are cork valve cover gaskets fine, or do I need to pay an extra $35 for the perma-dry-plus gaskets?

Any other thoughts or suggestions?

Thanks!

 

My standard response:

I'd be looking up above first. A leak at the back of the valve cover could produce the same symptoms. Don't jump on the RMS/oil pan gasket bandwagon just yet.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for 2 simple reasons. First off, the engine sits nose-up and oil will run back to that area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket have to be eliminated as possibilities first.
Revised 3-23-2012

 

Like cruiser said. Start with those areas first and hope it's not the RMS.
Good luck.
Robert

 

x3 above.

And to answer your question, DON'T CHEAP OUT ON GASKETS. Get quality Fel Pro rubber gaskets for your valve cover and oil pan

 

Thanks for the advice. Where can I buy the oil filter adapter gasket? Also, it probably won't come to this, but is the front main seal also known as the crankshaft seal?

 

oil filter adapter gaskets are not gaskets, just o-rings. take it all apart (2 mins) take all three o-rings to an industrial seal shop, and they will measure them and sell you new ones. material makes a difference here. Buna is most common and is designed for high heat and oil/gas applications. Don't use nitrile, they wont last as long.

X2 on the rubber vc gasket. i bought cork cause i try to cheap out, and now its leaking a year later!

 

I doubt you need a new engine. Pretty typical on these Jeeps with those miles. I'd get some fresh seals as others have suggested and just replace them.

 

X2

 

The oil filter adapter O-rings can be bought off the shelve at most part stores. Dont remember where I got mine but come will a bunch of o-rings and gaskets for Jeep and Chevy engines (weird i know) for like $10-12 or something. oh Link for exploded engine view

Dont think there is a front main seal, the timing cover seals the front of the motor.

Have blowby? try , super easy to make and works awesome for catching oil