Rear main seal

[1charger69]

Just finished replacing the seal....got the mancini end cap and silicone seal.....couldnt  see an obvious tear or anything but the the engine shop did NOT offset the seal halves....so i DID offset this time ....hoping it seals....

On a side note....it really wasnt that bad to swap it....did it un my garage on ramps

[A383Wing]

I have never offset my rear main seal halves.....also never had any leaks either

[Just 6T9 CHGR]

Just did mine again...after 14+ years I am now leak free...for now.
this time I used the Hughes Engines Billet retainer and a Viton seal

[Fred]

The Viton seal fixed my leak. Nine years and 34,000 miles later .........so far so good.  

[c00nhunterjoe]

Checked for excessive crankcase pressure?

[1charger69]

Interesting.....how do i check that?.....what can i do to decrease it?

[c00nhunterjoe]

You can buy a fancy tester,  but generally, pull the oil fill cap off and plug any other breathers, hold at 1800rpm, if the pressure out the cap will blow a rag off. its probably got some blow by.

[1charger69]

And how would i rectify that situation?

[1charger69]

It only leaks under load.....may give a pcv a try

[A383Wing]

I sense a re-ring in the near future

[c00nhunterjoe]

If there is excessive pressure, its 90% of the time rings.

[1charger69]

New rings?.....that motor is brand new.....got 80 miles on it

[Brass]

Just did mine again...after 14+ years I am now leak free...for now.
this time I used the Hughes Engines Billet retainer and a Viton seal

Did your rear main seal leak for the prior 14 years?  Do you have knurling on your crankshaft? I am considering the viton seal, so let us know how it goes.

[c00nhunterjoe]

Only leaks under load tells me its either crankcase pressure or a crankshaft that is walking exposing the sealing surface. Its possible to get a bad seal. Wait and see if it leaks again before worrying abkut it.

[1charger69]

I have 2 breathers on my covers.....should i try a pcv system?

[c00nhunterjoe]

Pcv doesnt do anything under wide open throttle. But would benefit cruising when engine is producing vacuum.

[Just 6T9 CHGR]

Just did mine again...after 14+ years I am now leak free...for now.
this time I used the Hughes Engines Billet retainer and a Viton seal

Did your rear main seal leak for the prior 14 years?  Do you have knurling on your crankshaft? I am considering the viton seal, so let us know how it goes.

Yep.   My chassis will never rust!  At least from the rear main back LOL

Yes knurled crank

Rebuilt the engine 14+ years ago.....Leaked upon start up....steady drip

Pissed off, I broke the fresh paint, pulled the pan in the car, and changed out the stock aluminum retainer for the Mancini Racing Billet one with the o-ring side seals & another rubber seal...STILL leaked but not as bad.....Id get a drip every 15-20 mins or so of running as well as some drips when car is off sitting in garage.
Ran it like that till now....still leak free although havent officially driven car this season yet....this weekend looks promising

[RammJaeger]

Just finished replacing the seal....got the mancini end cap and silicone seal.....couldnt  see an obvious tear or anything but the the engine shop did NOT offset the seal halves....so i DID offset this time ....hoping it seals....

On a side note....it really wasnt that bad to swap it....did it un my garage on ramps

I'm about to need to do this on the 440 in my Superbird. Do you have any tips on doing this? Can it be done with the engine in the car? I've read a little bit about offsetting the seal halves on various forums, but the descriptions don't really make sense to me. Can you explain a bit what it is?

It's kind of a bummer that I have to change the rear main seal. I just replaced the oil pan gasket, which hadn't been changed in 42+ years because it was leaking like crazy. Got that all finished up, and see that the rear main is leaking like crazy. Ugh!

Thanks

[Challenger340]

IMO,
it is NOT the Seal used....
it is NOT the Seal Retainer used....

it is that the groove in the Block is NOT in line with the Crankshaft centerline, but off to one side slightly. Hence one side of the Seal Lip is in TIGHT contact with the Crankshaft, and the other side of the Seal, the Lip barely touchs the Cranks = Drip.... Drip.... Drip....

I've posted this on numerous Sites, never seems to stick ?

I've assembled literally HUNDREDS of BB Mopars over 40 years, and when it's your JOB Oil Leaks are NOT Fun !, some Blocks the groove offset from Crank centerline is worse than others... but they all have some.
Remember here...
BB Mopars from factory were "rope" seals, so the factory never cared if the groove in the Block holding the rope seal was centered, because the rope just absorbed more Oil and expanded against the Crank on the loose side.
Roll ahead 30-40-50 years, and everybody sticks a Neoprene in there without CHECKING VISUALLY that the Lips on the Seal are compressing against the Crankshaft evenly on BOTH sides ?

NEXT time anybody reading this assembles a BB Mopar DO THIS:
With the Block on an Engine Stand
Install the Block half of the Seal in it's groove "Flush" with the Block
Install the upper Main Bearings
Set the Crankshaft in the Block (No Main Caps obviously)
Now take a Flashlight a LOOK at the dam "LIPS" on either side for how much each is compressed against the Crank !

It will then become obvious to many doing the above, that NO AMOUNT of ....."007"..... "Ancient Chinese Secret"....  "WHIZ-BANG $300 Seal Reatainer".... will cure an Oil Leak based in Common sense ?

The FIX is easy.... offset the Seal 1/4" on the Offending(loose) side.... offset the seal in the Retainer the same amount to match, then gently wiggle it together... but BEFORE Tightening the Retainer Bolts.... "gently" apply pressure with a small screwdriver lightly to one side to bring the loose side into contact with the Crank.

Apologies for shouting
I'm out !

[Fred]

Couldn't have said it better myself. 

[c00nhunterjoe]

Ron, he said it can idle all day long and not leak a drop, only leaks when loaded up. While the offset issue is well known, if it were the case here i would think it would leak all the time regardless of cruising or under hard loads?
Agreed it should always be checked and is an easy fix.

[Brass]

BB Mopars from factory were "rope" seals, so the factory never cared if the groove in the Block holding the rope seal was centered, because the rope just absorbed more Oil and expanded against the Crank on the loose side.

If the engine and crank are out, why not use a rope seal like the factory did?  Or maybe use a "sneaky pete" to put one in without pulling the engine?  Mancini carries GraphTite and I think Best brand is available.  In other words, are there any advantages to using a viton seal vs neoprene vs rope?  Will they each work with knurled cranks?  Thanks - I would really appreciate the insight.

[69wannabe]

I didn't have any leaks on my RB engine until I went with the stroker crankshaft. Leaked when I got it running and leaked after the machine shop tried to seal it so I went back and done the rope seal and it did good for about a year and a half and started dripping again. Last year I pulled the engine for a good cleaning and re paint and to try the rear main seal again and it also got some totally awesome LaRoy racing prepped stealth heads for the engine too. Did the offset rear seal with the seal ends at the 12 o clock and 6 o clock position and that was almost a year ago and it still is pretty good and dry under it besides the front of the 833 dripping a little bit of gear oil occasionally which it always has done that and it isn't very noticeable not like a steady drip. Maybe offsetting the seal lines it up good with the crankshaft and makes it contact the crankshaft properly helping to keep it from leaking. I saw it on a post that Ron had sent me and decided to give it a try and am glad I did since it's the first time in awhile it isn't leaving a good oil spot where it's parked. 

[Just 6T9 CHGR]

Drove mine over the weekend....leak free!