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Rear main seal

L

LABMBA87

NAXJA Forum User
Location
Oregon
Do i have to pull the trans to replace the rear main in my 94 XJ with the aw 4 or will the top seal roll right in without removing it?
 
Okay, First rear main i've done so any special ideas? I've heard to replace the oil pan gasket with the one-piece mopar gasket as it holds better. Any suggestions on time saving or not being stupid?
 
If the rig is lifted it will be easier to remove the oil pan, otherwise a stock height rig needs some suspension/steering stuff moved.

Get the late model oil pan gasket.

Use some Vaseline on the seal and be careful pushing the old one out and pushing the new one in. Make sure it's facing the right direction. You will need to remove the rearmost bearing cap. (Here's a good link http://www.jeepin.com/features/rearmain/index.asp )

Be certain to clean the bottom of the block really well....it will be the longest part of the job and by far the messiest. Just make sure it's right otherwise it'll leak.

Take your time.....think about the effort in doing it twice. ;)
 
Last edited:
Buy the rear main seal from the dealership seems to slide in better than the felpro (upper)........ lube it with clean oil........ one piece gasket is great .....oil pan can be a bit of pain to slip in/out.....also might have to loosen rear crankshaft bolts.......i would replace the oil pump while i was in there (thats what i do)........get a fsm for reference.......good luck....
 
My last experience included using some plastic setup pins that retained the gasket against the block and guided the pan into place so you didn't have to juggle the pan, the gasket and the first couple bolts and try to align everything. Ask the counterman if they have something like that.
 
http://208.101.10.250/~naxjaor1/forum/showthread.php?t=904242&highlight=rear+main+seal

I did a RMS a while ago, I wrote a post with a few things that I found helped out. Most of them are obvious, some of them are written other places and others are just observations I made.
It isn't a hard job to do, just take your time. Most people say 5-6 hours, and that would be accurate if you didn't have to scrape old gasket off yada yada. I spent several hours *just* scraping the old gasket off the block and checking for other wear while I was in there, and another hour cleaning the inside of the oil pan. Even though I had an air grinder, it still took a while to get all the gasket off the pan, and a real long time to clean out all the sludge in the bottom of the pan.
 
Alright guys, replaced the rear main. Was super easy and only took 2 hours. Biggest problem was getting the pan off. Everything went smooth with the help of some good friends and good tools. I can't believe shops charge so much for doing it though. I checked my rod bearings as well and there was some abnormal wear to the front side of the bearing as if the rod was bent. No "copper" shining through though so..... any ideas as to what could be causing that? Didn't seem to be any sludge in the ol' 4.0 so not sure what the prob is? any ideas?
 
John90XJ said:
My last experience included using some plastic setup pins that retained the gasket against the block and guided the pan into place so you didn't have to juggle the pan, the gasket and the first couple bolts and try to align everything. Ask the counterman if they have something like that.
Click to expand...

More info on these setup pins PLEASE PLEASE PLEASE.

I did my RMS a couple months ago. I made the mistake of going with some cheap gasket kit from Maako off ebay (I think they got kicked off since I bought the gasket). I'd never seen a gasket like the one that the 4.0 uses for the oil pan, so I didn't realize how brittle the cheap one I got was. Long story short, I ended up picking up the felpro one. Must better quality. No problems to date.

I have to replace the RMS on my sister's XJ soon and would love to know what those setup pins are and where I can get them because the most difficult part of the seal replacement was reinstalling the pan gasket.

Thanks,
Matt
 
I'm not sure where to get them as I work at a Dodge, Jeep store in Oregon and one of my tech's had a set. They're plastic and they thread into the 1/2" corner bolts. Then, they hold the gasket and the pan. Super sweet. Don't by the felpro gasket. Go to the dealer and buy the mopar gasket. It's like 10 bucks more and much better quality. Have you done a rear main seal before?? There are a couple good write ups in my other thread from some other guys on here. If you have any questions, feel free to ask. Don't forget to check your rod bearings while you got the pan off.
 
Yeah, I did the RMS on my XJ a couple months ago. A few days later, I left Florida and hit up Upper Tellico in NC. Put over 1K on it on my little road trip. Probably has 3k or so on it now. Seems to be holding up well. I checked and cleaned everything I could while I was in there. Everything looks pretty good. My XJ's a 93, but only has 70k on it. Just gotta finish putting my new floor pan in, so I can drive the thing again.

I'll have to do some research on the setup pins.

Thanks for the info.

Matt
 
Yeah, make sure you use assembly lube to toss that upper gasket in. I used grease and bent my first one. Used assemly lube and turned the crank and it went right in.
 
I just wanted to add that the one-peice rubber gasket was definitely worth it for me. It was much easier to install, and I think there will be less likelyhood of a leak later.
 
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