392 Hemi rear main seal leaks

Discussion of the 331-354-392 HEMIs.

Moderators: scottm, TrWaters, 392heminut

daveegt
Posts: 4
Joined: Tue Sep 15, 2015 10:54 am

392 Hemi rear main seal leaks

Postby daveegt » Tue Sep 15, 2015 5:49 pm

I just bought a car with a 392 Hemi, the rear main seal is leaking. T engine is a recent build. Can the rear main seal be replaced without removing the crank? Can they be replaced be just removing the pan and main cap? what is the best replacement gasket, seal, rope. I heard the the Ford big block (YE) is a good choice.
Any one have an answer, this is apparently a common problem with the rope.
Thanks, Dave

BlueDjinn
Posts: 43
Joined: Fri Aug 28, 2009 2:27 pm

Re: 392 Hemi rear main seal leaks

Postby BlueDjinn » Wed Sep 16, 2015 12:35 pm

A company that's been around since the forties is Jack Best's BEST GASKET for the vintage market.
Their part number for a rear main seal for a 57-58 392 is P/N 3A07. It is a two-piece neoprene that can be staggered from the main cap parting line. It can be installed without removing the crankshaft, but the main caps have to be loosened and the rear main cap removed for access.
If there's a rope in it, it can be removed with the caps loose and the rear main cap removed, digging at it with a dental pick and using a pipe cleaner to chase it around the journal. You'd NEVER get a rope in it working around the crank. Any time I did the rope seal it was with the crank out of the block. Switching to a neoprene seal actually frees up some horsepower that's lost through friction with a rope.
Use a lubricant like Super Lube or Sil-Glyde or Lubriplate 105 to install the new neoprene seal. DO NOT try putting it in dry AND make sure that the seal lip faces toward the inside of the engine against the oil, or it's in backwards and you won't be happy. Torque the main caps to spec @ 85 ft/lbs.
Don't go putting someone else's oil seal in there with shims and silicone. Put the FORD seal in the FORD engine. That's what it's made for. That's what it fits.

daveegt
Posts: 4
Joined: Tue Sep 15, 2015 10:54 am

Re: 392 Hemi rear main seal leaks

Postby daveegt » Wed Sep 16, 2015 9:23 pm

Thanks,this is the answer I was hoping to get. I will try this, it sounds like it will be the best answer to my leak.
Thanks again you have been a great help, I will stay on the forum.
Dave

daveegt
Posts: 4
Joined: Tue Sep 15, 2015 10:54 am

Re: 392 Hemi rear main seal leaks

Postby daveegt » Thu Sep 17, 2015 8:43 am

One more thought before I start on this project. Has anyone tried using any type of "oil stop leak" on the "rope" seal with any success? or is this a bad idea?
Thanks again, Dave

BlueDjinn
Posts: 43
Joined: Fri Aug 28, 2009 2:27 pm

Re: 392 Hemi rear main seal leaks

Postby BlueDjinn » Thu Sep 17, 2015 12:16 pm

Not too surprisingly, most people nowadays haven't the foggiest clue how to put a rope seal in an engine. Or a neoprene seal for that matter. Maybe yours is leaking because it wasn't installed properly in the first place. If it wasn't prelubricated before startup, the first turn of the crank would've done some damage. Maybe it wasn't packed in properly or got a ratty trim. Nevertheless, if the seal is leaking, then that's the problem. Replace the faulty seal with a good one and get over it. Don't waste your time on that genie-in-a-bottle. It's a band-aid repair at best and a short term one. Most oil stop leak is chemically engineered to swell rubber by the way. And that's all the rubber it comes in contact with. I won't allow that stuff in my engines. Just the proper oil, which already has its own additives.

daveegt
Posts: 4
Joined: Tue Sep 15, 2015 10:54 am

Re: 392 Hemi rear main seal leaks

Postby daveegt » Thu Sep 17, 2015 9:18 pm

That's what I thought, I was just hoping for a simple solution. I have never tried to use any of those " stop oil leak" products, but thought maybe there was something new.
I guess I will start on the engine
Thanks, Dave

moparjack
Posts: 9
Joined: Thu Dec 03, 2009 3:19 pm

Re: 392 Hemi rear main seal leaks

Postby moparjack » Tue Sep 13, 2016 7:47 am

daveegt wrote:That's what I thought, I was just hoping for a simple solution. I have never tried to use any of those " stop oil leak" products, but thought maybe there was something new.
I guess I will start on the engine
Thanks, Dave



I have tried the geneie in the bottle. It DOES NOT work.

Jack


Return to “(LEGACY) 331-354-392 HEMIs”

Who is online

Users browsing this forum: No registered users and 1 guest