So I have actually searched this topic and gotten some answers but I feel my situation is a tad bit different...

Well I recently replaced my rear main seal in my 1994 XJ and its now doing some funky stuff... When it has been sitting over night or just even a cold start the rear main will leak. Now its not spewing oil everywhere but its a significant "drip." So I immidiately shut it off wait about 2 mimutes and then fire it back up, drive it up and down the street, park it while its still running, let it idle for about 15-20 min and not a single drop! Then in other cases I will fire it up cold, let it sit and idle for again 15-20 min and again no leak... And thats on the first start up. Now I can't seem to find any rhyme or reason to why it is doing this and it is never consistant!! It will leak most of the time on cold starts then other times it wont even drip a drop on cold starts. But if it does leak and I shut it off then fire it back up and drive it around the block its perfectly fine. No drops. Any idea what is the cause of this?? Because I am just here scratching my head in confusion... I am 99% sure I installed the RMS correctly as I had some help from "5-speed" here on the forums.



So the big puddle is what it leaked when I first fired it up, was sitting for about 5 min. Then that little tinny drip is just left overs from the first start up... And that one drip was from it running in place for about 15 min.

 

Probably not the rear main seal.

follow this little diddy:

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, 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: “Crap 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.

 

Ive sat under while it leaks and from what I can tell it is a rear main leak. Oil pan gasket and valve cover gasket have both too been replaced and are leak free...

 

Ya he isnt kidding. His Jeep has a mind of its own. I have witnessed it. What he has not mentioned is that his engine is spotless thanks to a pressure washer. Clean enough to tell if it was leaking from the oil filter adapter area. It will literally leak, then shut it off, restart it and its fine.

 

Well now its doing something completely different... It never leaks when I start it up or when its running. Not a single drop! Now it only leaks when I shut it off... And it leaves about a bologna size puddle by the morning...

 

Put your eyes on it and find out what's going on!!!!

 

I have. Multiple time. Crawled under more than a few times and it is dripping down right where the RMS is... But only when its shut off now!!!

 

Well, if you see no oil above, put a rear main seal in it.