A rear main seal that is giving me fits!

SkylinesSuck

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So I just remembered why I was confused about that seal and the Ford seal; it is also interchangeable as a small block Oldsmobile RMS (which I also happen to have) but people cut the "wings" off the seal to install it. Not sure any of the aforementioned seals are in fact double lipped, but if the only way to get one is a version with "wings" and you need no wings, people have been known to cut them and install them in Oldsmobile engines to replace the rope style they come with from the factory with success.
 
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Tob

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oil pan seal rolled over
What does this mean and what would it look like?

Interesting discussion… I replaced mine using all fel pro stuff and immediately had a worse leak than before. I still think it’s because of installation error, but I may try the mopar RMS this time. Almost every other place I’ve read about the RMS has recommended fel pro as a seemingly gold standard.
 
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Irun

Irun

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What does this mean and what would it look like?

Almost every other place I’ve read about the RMS has recommended fel pro as a seemingly gold standard.
I've always thought this myself, which is why I've used Fel Pro on more than a dozen at this point. I'm willing to give the Mopar one a try though. :cautious:
 

pc1p

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I'm in the same boat with a leaky RMS that leaks now more than it did before hand...

Mine being an 05-06 has the extra added complexity of requiring the anaerobic sealer in specific areas due to their different cap design. I have read (here, but in different threads), that the trick to getting the cap to seal is to either use Mopar anaerobic sealer or use Ultra Black RTV instead. I have to do my soon since spring is coming and I don't want it leaking everywhere over summer. I may order a Mopar RMS while I'm at it. The Fel-Pro pan gasket does not seem to be the source of the leak (although on my first attempt it was, since the gasket "rolled" a bit in the rear and I didn't notice - even though I was anal about it!).
 
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Jezza

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My engine machinist told me once that the reason some engines have more problems with rear mains is due to the main bearing clearance. From what I understand if the rear main bearing has more clearance it will "flood" the seal with more oil than normal causing it to leak. He said the fix was to install a lower clearance bearing on the main to slow that flow down.
 
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machoheadgames

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They all call for Anaerobic sealer. The best product to use will be Mopar. Actually, the FSM told me to use a Loctite anaerobic product which is what I used. I believe the FSM later adjusted to tell you to use Mopar, which is probably the same Loctite product as before but in a Mopar container. Either way I would use one of those two myself.

With very little testing, I had no leaks on a victor reinz (Dana Spicer branch) OPG, then I had a leak with the Fel Pro, and then no leaks with another Victor Reinz. Not sure if I effed up the Fel Pro but I can’t help but wonder if Victor reinz is maybe the better option. Or maybe Mopar. I do like the lineup studs Fel pro gives you so I kept those from the FP kit and used them on the second reinz gasket.
 
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With very little testing, I had no leaks on a victor reinz (Dana Spicer branch) OPG, then I had a leak with the Fel Pro, and then no leaks with another Victor Reinz. Not sure if I effed up the Fel Pro but I can’t help but wonder if Victor reinz is maybe the better option. Or maybe Mopar. I do like the lineup studs Fel pro gives you so I kept those from the FP kit and used them on the second reinz gasket.
I've wondered if they are the OEM supplier for Jeep, since they're part of the Dana Corporation. When you read the description, and see the website, it kind of looks that way:

"With Victor Reinz gaskets, you can be sure you are getting sealing solutions that deliver OE quality gasket technology and engineering. That is because Victor Reinz is an original equipment supplier and the trusted choice of manufacturers the world over, offering broad coverage for foreign and domestic cars and trucks. In Victor Reinz gasket sets, you get the right combination of components needed for fast, long-lasting repairs."

 

machoheadgames

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I've wondered if they are the OEM supplier for Jeep, since they're part of the Dana Corporation. When you read the description, and see the website, it kind of looks that way:

"With Victor Reinz gaskets, you can be sure you are getting sealing solutions that deliver OE quality gasket technology and engineering. That is because Victor Reinz is an original equipment supplier and the trusted choice of manufacturers the world over, offering broad coverage for foreign and domestic cars and trucks. In Victor Reinz gasket sets, you get the right combination of components needed for fast, long-lasting repairs."

Yeah not sure either, I wondered the same thing. I do recall that both RMS and OPG had “improved design” in their description. Not sure if that’s boilerplate or true. My previous RMS and OPG for 6 years was Fel Pro and I don’t know what came out when the FP went in (2014), so not much to compare to.

I wish I could give more informative experience about how the Reinz stuff is working for me but I only have a few brief startups. Haven’t driven since I swapped, Jeep is still in project mode. I did let it idle up to temp in the driveway one day though for about 20 minutes and no leaks from that, so I am hopeful. Not saying VR is the only brand worth buying but seems like a solid option.
 
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Irun

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My engine machinist told me once that the reason some engines have more problems with rear mains is due to the main bearing clearance. From what I understand if the rear main bearing has more clearance it will "flood" the seal with more oil than normal causing it to leak. He said the fix was to install a lower clearance bearing on the main to slow that flow down.
This is interesting. He does have over 200K on the engine. Now I'm wondering if it might be a good idea to install a new set of standard main bearings? They looked fine when I pulled them, but I didn't verify clearances.
 

MangoTango

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I've done many rear main seals, without issues. However, I now have one on a friends vehicle that is being obstinate. I've helped him replace it twice and it still leaks ever so slightly. I know it was installed correctly and I didn't feel any groove worn in the crank. Any suggestions on what to do next? I really wish there was some sort of option that had two sealing lips and not one! :(
If it still leaks, check your thrust bearings for play on the crank. If there's a groove worn in the crank it will leak intermittently when the crank shifts enough to let the oil through that groove.
 

jeepguy03

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What does this mean and what would it look like?

Interesting discussion… I replaced mine using all fel pro stuff and immediately had a worse leak than before. I still think it’s because of installation error, but I may try the mopar RMS this time. Almost every other place I’ve read about the RMS has recommended fel pro as a seemingly gold standard.
I should've taken a picture of it, but basically what happens is right along the back side of the oil pan where it curves around the crank there isn't much supporting the pan gasket, it can shift and fold over a little bit towards the inside of the pan which makes it not sit flush against the sealing area like it is supposed to. Mine actually didn't leak initially, but started to about a day or so later.

FWIW I've used Fel-Pro and Mopar and have had success with both, I don't think the Fel-Pro is inferior, as the only times I've had issues they have been from installation error.
 
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Honeybadger

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Do any of you offset the RMS at all? Or just flush on both sides? Just finished this project and it’s leaking a bit from that area again. I’m thinking most likely user error with the oil pan gasket in that back area rolling over. Did use fel-pro for both and just going to swap RMS to Mopar when I go back in.

Any particular pointers on getting oil pan gasket back in correctly?
 

TJ Jim

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Not an answer, but if it makes you feel any better the previous owner had the rms replaced just before I bought it from him. It still leaked. Being the expert mechanic I think I am I replaced it again. It still leaks. There’s no wear ring on the crank, so like you I’m stumped how to stop the leak. Being anal about leaks, I’ll probably be back in there this winter to try again. It’s just a drip and maybe a quart low at the 5000 mile oil change so no big deal, just my head trip.
 
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Irun

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Not an answer, but if it makes you feel any better the previous owner had the rms replaced just before I bought it from him. It still leaked. Being the expert mechanic I think I am I replaced it again. It still leaks. There’s no wear ring on the crank, so like you I’m stumped how to stop the leak. Being anal about leaks, I’ll probably be back in there this winter to try again. It’s just a drip and maybe a quart low at the 5000 mile oil change so no big deal, just my head trip.
I had my buddy buy a Mopar RMS. If that doesn't work, I'm tapping out!

1650677397431.jpeg
 
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Tob

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LJBean

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I recently replace my RMS with the Mopar seal and seems to be working well so far. I used the Fel-Pro oil pan gasket because it came with those snap dowels to hold the pan up when starting the bolts.
 
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