pull that corn bread out your ears and listen here hillbilly, i put my overalls on one short leg at a time too!
Rear Main Seal Offset or Not and rtv usage
- Thread starter snowboundrmk
- Start date
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Warranty period is everything, and mopars was always 5/50 on pedestrian engines. Now if it doesn't make it through warranty it costs them lots of money to fix it.
M_Body_Coupe
Well-Known Member
Take a look at the attached pic, that's how I always set up my Felpro seal. The lip of the seal is positioned correctly as well.
Having said that, I have a continuous small leak today that I previously did NOT have on prior builds. The leak started right from the get-go, it hasn't increased, just remains annoying as hell.
I am running this with a Milodon 8 qt pan, can't quite tell where the leak is coming from though other than the fact that the bottom lip of the pan that seals the pan gasket is always wet and always has a drop waiting to "go"!!!
I jump both legs at the same time in mine ever mornin. I can do it still drunk from the night before with three hands tied behind my back.
The seal is like a bearing in that it needs some crush.
If you offset it like that you change the way the seal gets its crush in the bore.
You need to put the seal in the block and measure how much protrusion you have. .015 is plenty.
If it’s more that that you can trim the seal with a belt sander.
Go slow and sneak up on it.
I don’t know where the idea of offsetting the seal came from but when I worked for a production engine rebuilder we were losing our asses on leaky seals.
I got on the phone with an engineer from Chicago Rawhide (CR seals) and he told me what the fix is.
Our rear main seal leak warranty claims went to near zero in 60 days.
One piece seals have their own issues but we had issues with those too.
M_Body_Coupe
Well-Known Member
I won't argue what you say, but I will at the same time re-state what was already linked to in this thread, that being: FelPro has a very specific recommendation for HOW to install their seals (see attached PDF), and they in fact call for that off-set placement.
My point was only to state that I've done so, and yet I have some kind of a leak, although I cannot tell if that's an oil pan leak, or actual seal leak.
Happy to troubleshoot that further though if there are some specific recommendations for isolating these!
Interesting.
I never called FelPro because we weren’t using their seals. That’s why I called CR. It was their seals. Even the one piece seals.
I can’t say what the benefit is of offsetting the seal.
They don’t leak (according to CR) because the parting line of the seal is parallel to the parting line of the cap.
They leak (according to CR) because the parting line of the seal is proud of the block, cap or both.
When that occurs the seal is crushed to the point it goes out of round and it leaks.
I’ve installed hundreds of seals, many of the FelPro and 95% of the time I need to shorten one half or both halves of the seal.
And not just on Chrysler stuff.
I’d call FelPro and ask them about it but I’m not sure what they could say that would change my understanding of how a two piece seal functions.
Brian Hafliger
Well-Known Member
While moving on to my next build, I thought I would show what I do with BB Mopars. This customer supplied an SCE seal, so I thought I would mock it up...wow! without trimming it would have leaked soooooooo bad!
The Felpro is just about perfect as you can see. I offset the seal, and the reason is to allow the seat retainer to better locate in the block to keep the seals lined up, top and bottom. I only offset a little bit, like .250. I mock up every block/seal I build so I can make sure the seal is aligned, round, and has decent push on the crank surface it rides on. The last pick is the seal placed non-offset, and with the seal adapter bolted on as if I could not see the alignment (as if the crank was in the block). You'll notice the seal holder is slightly forward causing a misalignment of the upper and lower halves. This is why I offset slightly.
The Felpro is just about perfect as you can see. I offset the seal, and the reason is to allow the seat retainer to better locate in the block to keep the seals lined up, top and bottom. I only offset a little bit, like .250. I mock up every block/seal I build so I can make sure the seal is aligned, round, and has decent push on the crank surface it rides on. The last pick is the seal placed non-offset, and with the seal adapter bolted on as if I could not see the alignment (as if the crank was in the block). You'll notice the seal holder is slightly forward causing a misalignment of the upper and lower halves. This is why I offset slightly.
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