sudden Rear Main Seal (RMS) Leak

About 2 weeks ago after sitting for about a month. I started the Jeep and noticed there was a pretty massive oil leak at the back of the engine between the pan and the Trans. I have rulled out the valve cover, Oil filter, and Distributer as the sorce of the leek, and It really does look to be coming from the RMS. My Question is this... Is it common for a RMS to fail so suddenly and drasticly? I am loosing the better part of a quart of oil every time I drive 30 miles. The other confusing thing is there were 2 pin holes that showed up at the front of the pan that were leaking. (patched with JB weld). no damage and I know I didnt hit anything.

If it was summer I would just bite the bullet and change the RMS and Pan Gasket. But now that its getting cold I really shouldn't be out in the driveway under the Jeep for a weekend. Is there anything else that MAY be causing this? I especially dont want to do the repair and find out it was caused by something else.

Thanks for the help.

Ed


'88 4dr, XJ, 4.0 I6, Auto, 205,000miles

Usually the oil filter adapter o-ring seals failing will cause the engine to leak that much. Check for the oil leaking from the bottom of the adapter where it meets the block.

Hi,
I would also go with the oil filter adapter O rings, an excellent write up on changing them can be found here http://www.go.jeep-xj.info/HowtoOilAdaptorOrings.htm When I did mine I put RTV on both the engine block and the adapter housing before bolting it back up, 12 months later it's still dry as a bone. It sounds like you have rust perforation on your oil pan, you might want to brush engine oil all over the oil pan to prevent it getting any worse, or clean it up and use a good quality engine type paint.

thanks for the replys guys, but this leak is not coming from the oil filter adapter. it is dry around it. I am familiar with that leak though I had it not long back and replaced the O-rings. I am 99% sure the leak is from the RMS I am just surprised at how suddenly & drastically it started. I was wondering it it were possible that the Crank Case Pressure went up somehow to cause this, and how would I check that. It just seems really strange to have 2 pretty major leaks at the same time like this.


Thanks again for the help.

When it was sitting for 2 months did you ever start it and let it get to normal temp? It is possible that if you didn't do that then the seal could have dried out a little and when started up caused damage to it allowing the pressure to push the oil out. As for the front pinhole leaks were they in the pan itself or in the gasket?

Dave

It only sat for about a month, probably a bit less. I did not start it in that time.

The pin holes were in the pan itself.

Thanks for the reply,
Ed

Dood, joo gots gremlins...... Mabye theres loose bolts?///

Wally's been sippin on some syzzurrupp

When's the last time the valvecover gasket was replaced?

I'd do that first to make sure nothing else can be the cause of this leak. Alot easier to do the valvecover than the RMS that's for sure, and if it is the RMS you didn't waste much time.

When you noticed the leak had you been driving it at all or was it sitting in the same spot the entire time? If you had driven it at any speed it's also possible the oil pressure unit went bad which would have enough pressure to spray oil all over the place and then run down the flex plate making it look like a RMS.

Blane,

The VC gasket was just replaced. when I noticed the leak I ran right out and replaced the VC gasket. It is sealled up perfectly now. I can run my hand around it completely and not get a single drop on my fingers. So its not the VC. but it was my first thought.

Dave,

I noticed the leak after it sat for that month, I warmed the jeep up and was taking it out for a drive. As soon as I got on the highway I noticed was leaving a smoke trail (oil dripping on the exhaust pipe).

I have been laying on my back under the jeep while it is dripping and it does seem to be coming from the area of the RMS. I can reach up arount the oil sending unit while running and it is dry.


Too funny wally & gradon, I do have gremmlins.

This jeep is running better than it has ever run. but now is leaking so much oil I really shouldnt drive it.


Thank for all the replys so far guys. It is greatly appreciated.

Ed