So I just got my third XJ and feel great to finally be back in the 4.0. Needs a bit of attention, but nothing major. The other day I floored it turning onto a street and immediately after got a bad oil leak. It looks like the RMS needs replacing. I am tackling that today. Just posting for any ideas of anything else it might be in case the RMS doesn't fix the leak.

Basically, would pushing the old girl that hard be the cause of blowing that seal possibly? What else would go from flooring it that would cause this leak?

My valve cover gasket is new from previous owner. I checked and I do not see any leaks coming down the back of the engine.

 

If it hadn't been driven in awhile, or went through long periods of sitting, RMS can always be a prime suspect. Losing a ton of oil fast can indicate a RMS, but read cruiser's tip about diagnosing it first - since it could be a few other things.

When doing it, obviously you can do the pan gasket, which is probably leaking slightly anyway.

Also commonly the oil filter adapters can leak, and as you know - most oil leaks will wind up down near the RMS, so make sure to really diagnose it first, cuz the oil pan isn't going to be too much fun to remove, so only do it if you know you have to.

 

In normal operation the seal is about 4 inches above the oil level so the leakage it contains is oil that is splashing around plus the oil being delivered to the rear main bearing. Heavy acceleration or a steep incline can flood oil to the rear seal.

 

Thanks guys. Only 4 hours in and I just got the oil pan off. Hopefully the rest goes smoothly. I must say, I do miss having lifts and power tools at my disposal. This driveway mechanic stuff just sucks.

 

I'm right there with you bro. Have put countless hours into my trucks in my parking spot.

How was it? Did you just jack up the unibody to clear the drag link/track bar and stabilizer or did you have to take them off? I already cut my trans cooler lines and ran them to a new cooler, so at least I don't have to worry about that.... Having to take off the steering components wouldn't suck TOO bad since I just did them recently, but I'm hoping I won't have to.

I only ask because I'll be doing this myself very soon.

You might want to look into what else you can do while it's off. I read a few things you can do, like timing cover gasket set? Few other little things I think, but not sure how worth it any of it is, just a thought.

 

The timing chain was done not long before I bought the Jeep. Which is aggravating because the Oil Pan Gasket was nice and new already. I was thinking of putting a new oil pump in but decided against it. If I had to do this again tomorrow, I would drop all the steering components. I ended up breaking my trans lines so I have to replace them tomorrow. Getting the oil pan off then back on was the most time and it would have been no problem at all if I dropped the steering components. If everything is new then I definitely would. I jacked the frame up and put jack stands just behind the lower control arms.

 

I'll bet the true cause of the leak is oil filter adapter seals........

 

Close! after getting the RMS and pan gasket back in and patching the Transmission cooling line I busted in the process the leak remained...

Final verdict was the oil pressure sending unit.

Nothing like investing the time into the RMS then it turning out to be the super easy, super quick fix.

Lessons learned and next time I will make sure to not get to set on one thing.

Thanks for all the help guys!

 

That's why I wrote this years ago:




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