1969 440 chrysler rear main seal

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hadmtrst8
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1969 440 chrysler rear main seal

Post by hadmtrst8 »

any one have a recomendations on rear main seals,leakage probs on these motors using felpro rubber seal?2 seals both leak after 2 -3 minutes of run time on test stand ,windage tray possible cause?oe nos, matching car, so not looking to add evac hoses, thanks
Walter R. Malik
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Re: 1969 440 chrysler rear main seal

Post by Walter R. Malik »

hadmtrst8 wrote: Wed Jul 28, 2021 11:46 am any one have a recomendations on rear main seals,leakage probs on these motors using felpro rubber seal?2 seals both leak after 2 -3 minutes of run time on test stand ,windage tray possible cause?oe nos, matching car, so not looking to add evac hoses, thanks
The seal is probably to long ... when crushed, the sealing ridge is hardly pressing against the crank or is not round.
One end of each half needs to be trimmed to get the correct crush amount.

Mopar also has a lower bearing half with special grooves to help that situation.
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BradH
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Re: 1969 440 chrysler rear main seal

Post by BradH »

What's worked OK for me the last couple of rebuilds with an OEM seal retainer has been using Viton seals, plus the Viton strips for the sides of the seal retainer (although I know people who don't have issues w/ the standard side seals).

I have no experience with this one-piece seal vs traditional two-piece seals. I like the idea... not so much the $$$: https://fastfishautoparts.com/store/p_1 ... main-seal-

My last build I switched to one of the billet seal retainers that use o-ring material as the side seals; no issues from the engine dyno session, but it hasn't been run on the street, yet. More than one company offers a billet retainer (and they're not all the same), but I happen to use the one available through Mancini Racing --> https://www.manciniracing.com/bilrearmains.html. I have one on the shelf from Indy Cylinder Head, too, which is how I know at least those two aren't the same item. Some of the billet retainers use OEM-type side seals, rather than o-ring strips.

Another thing to look for, especially w/ the OEM retainer, is when you're using main studs, rather than bolts. The top of the studs may stick out far enough that the retainer is bumping up against it when tightened down and won't let it fit properly against the cap surface of the block. Some of the billet ones are clearanced here, but not all IIRC.
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Re: 1969 440 chrysler rear main seal

Post by BillK »

I simply have never had a rear main seal problem on a Big Block Mopar using the Fel Pro stock replacement seal ? Are you absolutely certain it is the rear main seal leaking ?? Put some UV die in it to be sure. What I do on the back of the seal holder is make sure it is perfectly clean and then fill the entire "cavity" with "The Right Stuff" and smooth it off.

One question ....... is it the original crankshaft out of the engine ? Reason I ask is I had a customer do one many years ago and got a crank kit. Turned out the crank in the kit was for a reverse rotation marine engine and the little grooves on the seal surface were in the wrong direction. Pumped oil out like crazy. I suppose a reverse rotation rear main seal would do the same thing.

When you get it back apart post some pictures of the crank and the seal.
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Re: 1969 440 chrysler rear main seal

Post by rebelrouser »

does it have a stud girdle on it? Some of those need material removed so the oil can run back to the pan. The good ones have a oil return slot machined in them, the cheap ones don't.
I seldom have trouble with the standard replacement rubber rear main seals. some of the OEM seal retainers have sharp point in them to hold a rope seal in place, sometimes you have to take a die grinder and remove those points as it distorts the seal when you tighten down the retainer. I had one 440 that had been line bored, and it took an billet seal holder with a little material taken off it to get the main to quit leaking.
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Re: 1969 440 chrysler rear main seal

Post by engineman1642 »

check runout on seal area on crank.had one years ago that would leak after short run time.it had about .014 from what i can remember.
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Re: 1969 440 chrysler rear main seal

Post by Geoff2 »

I have fitted a one piece seal to a recent 440 build. Engine is not running yet. I had the serrations machined off the crank, 0.010" off the OD is enough. Serrations & rubber seals do not get along too well.

Aftermarket seal retainers. I had two of them & both compressed the seal 0.015-0.018" more than the factory retainer, giving the seal an oblong shape, not concentric, & varying the seal pressure on the crank. I used the factory retainer. Before installing, I fill the side grooves with silicon & leave overnight to cure. Retainer is then installed with small amount of sil behind seal & sil on side & bottom of retainer to seal it.
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Re: 1969 440 chrysler rear main seal

Post by BILL-C »

Walter R. Malik wrote: Wed Jul 28, 2021 12:03 pm
hadmtrst8 wrote: Wed Jul 28, 2021 11:46 am any one have a recomendations on rear main seals,leakage probs on these motors using felpro rubber seal?2 seals both leak after 2 -3 minutes of run time on test stand ,windage tray possible cause?oe nos, matching car, so not looking to add evac hoses, thanks
The seal is probably to long ... when crushed, the sealing ridge is hardly pressing against the crank or is not round.
One end of each half needs to be trimmed to get the correct crush amount.

Mopar also has a lower bearing half with special grooves to help that situation.
.
We usually trim the seal ends to get .010 protrusion per end.
Carlquist Competition Engines
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