Rear Main Seal Replacement (4.0)

Well it’s been about 300 miles. And it started to leak again. It seemed pretty straight forward i don’t know what I could have done wrong. I guess i’m going to try it one more time. Seems like the 2 piece design makes it about 2 times easier to replace and about 10 times more likely to leak. I don’t know which one is better. You guys have any thoughts on what commonly goes wrong.
 
chad said:
Well it’s been about 300 miles. And it started to leak again. It seemed pretty straight forward i don’t know what I could have done wrong. I guess i’m going to try it one more time. Seems like the 2 piece design makes it about 2 times easier to replace and about 10 times more likely to leak. I don’t know which one is better. You guys have any thoughts on what commonly goes wrong.
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Not clean enough or installed wrong.
 
chad said:
Well it’s been about 300 miles. And it started to leak again. It seemed pretty straight forward i don’t know what I could have done wrong. I guess i’m going to try it one more time. Seems like the 2 piece design makes it about 2 times easier to replace and about 10 times more likely to leak. I don’t know which one is better. You guys have any thoughts on what commonly goes wrong.
Click to expand...
I never had the urge to change mine after the first leak. I just felt that it will leak again.
 
Well it’s been about 300 miles. And it started to leak again. It seemed pretty straight forward i don’t know what I could have done wrong. I guess i’m going to try it one more time. Seems like the 2 piece design makes it about 2 times easier to replace and about 10 times more likely to leak. I don’t know which one is better. You guys have any thoughts on what commonly goes wrong.
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I have not done mine, but from what I've read, sealant only goes in specific areas of the oil pan. Where did you put your sealant?
 
chad said:
Pretty much exactly where Chris sad in the instructions with the correct type of sealant. I’m guessing I must have nicked the seal when I slid the top one in.
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I ruined the first upper seal because I got impatient with the paper shoe horn FelPro gives you, the shoe horn is a must but makes it twice as hard to feed the seal around.
 
chad said:
Pretty much exactly where Chris sad in the instructions with the correct type of sealant. I’m guessing I must have nicked the seal when I slid the top one in.
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I previously posted the below link, but this write-up/guide is for owners of 2005 and 2006 model years, and can be used in tandem with the original posting. This version includes lots of pictures and may give you insight, or the "ah-ha moment" where you may have gone wrong.

http://www.fourwheeler.com/how-to/engine/1803-how-to-replace-a-jeep-4-0l-rear-main-seal/
 
Well I took my time today and replaced my rear main seal again. I didn’t see anything obvious. Gonna Let the permatex dry for 24 hours and I guess we will see if I got it this time. Only time will tell. Only thing that I could think of that would be worse is paying someone to do and it still leaking lol. I did remember that when I received my order from amazon the seal was thrown in the box with a bunch of other stuff and the plastic bad bag the seal came in was beat up pretty good. Thinking maybe that had something to do with it because the job itself seems pretty easy. I’ve been turning wrench’s since since I was a kid and never ran into something I couldn’t do.
 
chad said:
Well I took my time today and replaced my rear main seal again. I didn’t see anything obvious. Gonna Let the permatex dry for 24 hours and I guess we will see if I got it this time. Only time will tell. Only thing that I could think of that would be worse is paying someone to do and it still leaking lol. I did remember that when I received my order from amazon the seal was thrown in the box with a bunch of other stuff and the plastic bad bag the seal came in was beat up pretty good. Thinking maybe that had something to do with it because the job itself seems pretty easy. I’ve been turning wrench’s since since I was a kid and never ran into something I couldn’t do.
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Finished my replacement about a week ago, so far so good. One thing I did do was after I finished I let it sit for a week before starting it, because its not my primary vehicle. Don't know if that made a difference or not.
Put about 200 miles on it this past weekend and so far its good.
I hope your replacement goes well.
 
Success I now have a TJ with no leaks anywhere lol. One side note 3 years ago when I got my TJ I put synthetic oil in it and shortly thereafter I developed RMS leak. I chocked it off as a coincidence sense every thing I have read says that modern synthetic oil no longer causes oil leaks. So when I change my RMS The first time I put synthetic oil in it again and it leaked again. I didn’t do anything differently from the first time I changed the seal except this time I put plan 10W30 pennzoil and it’s completely dry after 300 miles or so. Could just be a coincidence. Draw your own conclusions. Just thought that I would share my experience.
 
I read this whole thread and there is some great stuff in here. I thought I could add a few more bits of technical info from the shop manual. This is specifically for a 2005 LJ 4.0. I think the main reason a newly installed seal will leak is that it gets cut during install and or the sealant is not done perfectly. Also some might be interested in the service bulletin related to the main seal.

p1.jpg


p2.jpg


p3.jpg


p4.jpg


p5.jpg
 
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Working on this now and the instructions have been great. A couple of questions for the Gurus:

1. How much anaerobic sealer should be put on the bearing cap? Some say a drop, while other online pictures show a bead.

2. Do I lube the upper seal with soap or oil?

3. Some of the online instructions state to put a bead of RTV on the lower seal before install. Is this a good idea.

As always - Thanks for any help!
 
I would go with the FSM specs above. And use the correct type of sealant as specified above.

I just did this on mine and no more drips!
 
The FSM above confused me a little and actually generated the question about the sealant. Did you apply sealant to both the bearing cap and the block or just the bearing cap?
 
The diagram is confusing because it only shows the block. The text actually says to put sealant on the block and the bearing cap but references the same diagram in both cases. I did what the text says as close as possible.
 
Finished this last week, following the fsm directions above and I now have zero leaks. It took me a long time, but it wasn’t all that difficult.
 
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