95JeepZj

I found somewhere on the web where a guy posted a step by step process on how he replaced the rear main seal on his Xj. same motor and trans that's in my Zj. Anyone out there have any pointers? I don't want to drop a trany unless I totally have to which I know I don't. Any help would be great. ie: pointers tips. Trans fluid started leaking today with about 40min of 70mph highway speeds... what a bummer. (it's lifted on 33's btw)

I know I'll have to take the yoke off that holds the crank shaft to expose the lower part of the rear main seal but I have never done it. Thanks for the help guys!

Bustedback

If you're leaking trans fluid changing the rear main seal is not going to fix it. You may have a front pump seal, torque converter seal, cooler line, or trans pan gasket leaking.

Thaimonkee

That corect. Rear main seal will leak engine oil from in between where the engine and trans meet. Usually will be leaking down the rear of the oil pan.

95JeepZj

Hmmm... Well I know for sure the RMS will need to be replaced because it is currently on a 2-day oil refill regiment!

I'll have to look into the trans leak, it's not the pan gasket, it's dripping down from the bust plate where the bell housing bolts to the block, I didn't look into it to in depth because it started to get kind of dark.

95JeepZj

I go through this process:
Oil leak from oil pan, replace gasket, leaks a couple drips more a day
The same thing happened to a 351W I had in an 89 short bed ford.

95JeepZj

My Zj, just for those curious!

Bustedback

I would start with confirming the source of the leak, rear main seals don't go out as often as you think. If you have the 4.0 you could bet on the oil filter adaptor orings leaking, and those are under pressure, which explains the rapid oil loss.

95JeepZj

By oil filter o rings I assume you mean the o ring on the filter itself. That oil filter has only 2k miles on it and last I looked wasn't leaking. I'm pretty positive my rear main is leaking and I found the thread or web site the guy has about his Xj and his modifications to his intake. I got an intake from a newer grnad Cherokee 4.0 I'm going to put on my jeep as well as the injectors. Too many things to do in so little time!

Bustedback

No, not the oil filter oring. There are three orings on the oil filter ADAPTER, and the one that seals the ADAPTER to the engine block will leak. The oil runs to the back of the engine and makes it look like the rear main seal is leaking.

95JeepZj

I was not aware of that. I'll have to take a close look, thanks for the advice!

dave1123

I'm assuming it's not transmission fluid as you originally stated. If the rear main OIL seal is leaking, you'll have to pull the oil pan and rear bearing. You can "roll" out the top half of the seal without too much trouble. The bottom half is in the bearing cap. Just make sure it's NOT the filter adapter o-rings or the pressure sensor before you go that far.

You never said whether it was a I6 or V8 either. If it's a V8, it's probably the pressure sensor which is behind the distributer on top of the block. You'll have to remove the oil pump on the V8 to get to the rear seal.

95JeepZj

It is the 4.0 I6. And it has been leaking oil from the rear of the block for a little while and I'll just add oil accordingly. Just recently the trans fluid started to leak from the dust plate on the front of the bell housing.

dave1123

Okay, tranny fluid coming out of the bellhousing is indicative the of input shaft seal where the torque converter goes into the front pump. That will require pulling out the transmission OR the engine to get to it. On my Chevy truck, I just broke it apart and slid the trans back to change the torque converter. This may not work with a Jeep because I'm not sure if the rear crossmember is bolted in or welded. There is a seal ring on the front of the pump that the torque converter rides on. This can be changed without much fuss but is a PITA to get to. Check the sleeve on the back of the converter for a groove where the seal rides. A groove will cause the new seal to not last long, but can only be fixed by replacing the converter.

Make sure on reassembly that the converter is fully rearward and engaged with the pump drive tangs. Before you draw up the bellhousing bolts, make sure the torque converter spins freely. If it doesn't, it not engaged with the pump. If you draw it up tight and it isn't engaged, it will break the pump! Be careful.

ALSO, use care with the crankshaft position sensor when you do this.

NewJerseyXJ609

To answer your question... It's alot simpler than you think... Pop the oil pan and take the main cap bolts out. Remove the cap. Take the bottom piece of the seal out. Use a hook or a pick to push the second half around and out. Repeat procedure to put it back in. I can't remember the torque specs for the main off hand.. But that's it.. Did it on my zj in a half hour...

Woops ^

dave1123

I agree with you, Jersey. The hard part is the torque converter seal.