A rear main seal that is giving me fits!

TJ Jim

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Feb 12, 2021
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The joke being that the original seal that came in the vehicle is notorious for leaking? Or do you mean that people have problems after replacing the seal with a Mopar?
I think I’m kinda getting the joke now. 🙄
 

eastbloc

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2 years ago I did mine 3 or 4 times in the row with no luck, still had a slight leak that i learned to ignore.
Last fall, after not being driven for 5 month, oil leak got worse to the point of losing 1qt/1000 miles. Now i hope if i don't look, it will magically fix itself
 

TJJeep4Sale

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Jan 26, 2022
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Southern CA
Mine had to be redone 3 times before they finally tried an OEM Mopar seal and it stopped leaking. I bought it from a dealership that essentially flips Jeeps. They said the RMS is basically part of their standard flip a TJ package as every single one they buy leaks there. So they do them day in and day out but mine for some reason wanted OEM before it would stop. It is a used car dealership/auto shop and I'm just going off of what they told me so take it with a grain of salt YMMV
 
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Irun

Irun

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Hey @Irun - you get your OPG/RMS fixed? What gasket did you try?
I was helping a buddy on his Jeep. We had already done the RMS 2X (with a FelPro RMS). This time we used the traditional FelPro OPG, but a Mopar RMS. My buddy reports no oil leaks so far. It's a weird one for me, because I've installed numerous FelPro RMS with no previous problems. :unsure:
 
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pc1p

I do all my own stunts
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I was helping a buddy on his Jeep. We had already done the RMS 2X (with a FelPro RMS). This time we used the traditional FelPro OPG, but a Mopar RMS. My buddy reports no oil leaks so far. It's a weird one for me, because I've installed numerous FelPro RMS with no previous problems. :unsure:
Same here - not just in Jeeps but in a handful of other vehicles with zero issues. I'm wondering if the FelPro part has had a retool or redesign, causing the issue. I ran into the same thing recently with Timken Dana 44 rear axle seals. I have never had a leaking Dana 44 axle seal and the last two I rebuilt with Timken seals have leaked, one right from the start and the other very shortly thereafter (one of those leaked twice!!). We moved to Spicer seals and never had a single issue in over a year.
 
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eastbloc

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Yesterday i redid my rms for the 4th (or 5th) time - mission success!
This time i used Mopar instead of FelPro, and applied much more sealant on bearing cap.

I looked at Mopar and FelPro rms side by side and could not see anything that would make one or the other better or worse. Other than color, they are pretty much identical. Old FelPro was in good shape, holding its form and no signs of being worn out. Overall i am very skepticap that the issue is in the seal, and more suspicious of factory instructions for sealant application.

Before i went with factory manual instructions which roughly looks like this
Screenshot_20220805-160239~2.png

This time i replicated youtubers approach
Screenshot_20220801-181818~2.png
 

Honeybadger

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Mar 14, 2019
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SoCal
Yesterday i redid my rms for the 4th (or 5th) time - mission success!
This time i used Mopar instead of FelPro, and applied much more sealant on bearing cap.

I looked at Mopar and FelPro rms side by side and could not see anything that would make one or the other better or worse. Other than color, they are pretty much identical. Old FelPro was in good shape, holding its form and no signs of being worn out. Overall i am very skepticap that the issue is in the seal, and more suspicious of factory instructions for sealant application.

Before i went with factory manual instructions which roughly looks like this
View attachment 348524

This time i replicated youtubers approach
View attachment 348525

About to do mine a third time, maybe I’ll apply more sealant this go around like this. Second time used Mopar RMS and I noticed not nearly as tight of fit as the Felpro was the first time. The leak was less with the Felpro but was still bugging me after all that work. Going with Mopar oil pan gasket vs blue Felpro. Hopefully it’s the right combo this time.
 

eastbloc

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About to do mine a third time, maybe I’ll apply more sealant this go around like this. Second time used Mopar RMS and I noticed not nearly as tight of fit as the Felpro was the first time. The leak was less with the Felpro but was still bugging me after all that work. Going with Mopar oil pan gasket vs blue Felpro. Hopefully it’s the right combo this time.
Before you asked about offset, are you planing to do it?

As far as oil pan gasket, i think if there is issue with it properly seating it will be spewing oil in significant amounts. That back lip is truly a pita, once pan is aligned there is no way to see or control how it mates with the surface, it was concerning to me as well. But if you think about it, as it gets tightened the seal will move into its designated spot, or away from it, there is no in between. So if you get a leak from improperly seated oil pan gasket, it will be very evident.
What you can do is apply something like Permatex Super 300 between the gasket and oil pan, it is sticky and will hold gaskep in place. After discovering 300 i began using it on all mating surfaces that don't call for RTV with a great success, have nothing but bood things to say about it.
 

Honeybadger

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Mar 14, 2019
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Location
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Before you asked about offset, are you planing to do it?

As far as oil pan gasket, i think if there is issue with it properly seating it will be spewing oil in significant amounts. That back lip is truly a pita, once pan is aligned there is no way to see or control how it mates with the surface, it was concerning to me as well. But if you think about it, as it gets tightened the seal will move into its designated spot, or away from it, there is no in between. So if you get a leak from improperly seated oil pan gasket, it will be very evident.
What you can do is apply something like Permatex Super 300 between the gasket and oil pan, it is sticky and will hold gaskep in place. After discovering 300 i began using it on all mating surfaces that don't call for RTV with a great success, have nothing but bood things to say about it.

I did the offset the second time and probably shouldn’t have. Pretty sure that’s why it’s leaking. Will look into the Super 300, thanks for the recommendation