Wingin1t

92 XJ
4.5in Lift
32s
Stock gearing.
(Dont know if that is useful)

So this is my second 92. I've come to realize that 70+ mph for long periods of time causes moderate engine oil leakage.

1st XJ had leak. Replaced RMS/Oil Pan Gasket. No more leak. Drive cross country, moderate to severe oil leakage. Never got around to fixing it second time, Sold as is before my move.

2nd XJ (Current) no leaks period. Drive from SF Bay area to Vegas, first gas stop I have that same old oil leak again minor to moderate.

Question: is the rms more likely to be the issue and just failing after long drive at 70+ mph? Or would it be the oil pan gasket blowing out?

It always leaks from back of the engine where engine and trans meet. Yes I know it's engine oil.

I'm still in Vegas and figured I'd see if it is common for one or the other to go bad when driving long periods of 70+ mph.

Thanks!

docmedpros

OFA is another area of leaking prone on XJs. I'd power wash all the oil off. Drive for a 5 miles or so and see if you can pin point the leak. Don't forget your motor sits with the front slightly above the rear so everything will travel down and towards the back of the motor.

MonacaYankee

Do you have oil on the bottom of the oil filter? If so you need to replace the oil filter adapter o-rings.
Replace the factory valve cover gasket with a gel-pro one.

Both of these will get your oil leak down to a quarter spot a day like both of my jeeps. Rms needs changed but not worth it for me for minor leakage.

cruiser54

Here ya go:




I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.

Many mechanics, friends, people on Jeep forums who can’t see your Jeep from where they’re at, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.

First off, the engine sits nose-up and any oil will run back to the RMS 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, in that order, have to be eliminated as possibilities first.

Revised 02-26-2013

Wingin1t

Ok thanks! Off the bat I replaced the valve cover gasket with the fancy blue one about 2 weeks ago so the top of the engine has actually been dry. I'll check the rest when I get a chance and keep everyone updated.

Thanks!

Crazy 8s

Blockage in the CCV system will push oil out of the RMS too. Make sure those hoses are clean.

N Ga Rider

I feel your pain, I have replaced my valve cover, oil filter adapter O rings and pan and rear main seal. I cleaned engine prior to doing this. Rear main slightly leaking. No oil coming from anywhere else. Mine is a 1991. I might try and do the rear main one more time when I can.

forcefed44

Weather has been odd here.. I need to do this too. picked up the usual suspects: Oil filter kit, RMS, and valve cover along with new vacuum elbow and PVC's.. Lets see...

Wingin1t

What sucks about doing it all at once without finding where it is coming from is that you don't know where to look immediately if it happens again. Kinda my situation. I get that "if I'm down there I might as well do it all" mentality. Still in Vegas but heading back to Cali tomorrow and will be able to get into it more in depth and update you all.

Wingin1t

As of right now I'm going to say it was a combination of an old brittle RMS, as well as a brittle OPG. The RMS just about broke apart when being removed and the OPG was an old Fel-pro that was cracking and splitting. Replaced them both and no leaks yet. Haven't taken it on a long trip yet either to test it haha.