Rear Seal Replacement on 312' Y-Block


http://209.208.111.198/Topic8631.aspx 		Print Topic | Close Window

By Tough55 - 18 Years Ago
Rear seal leaking on my 1957 Merc. 312'. It is in a 1955 Ford Customline with a 4-Speed.  Can this job be done with the engine in the car?  I would appreciate it if someone would take the time and walk me through this one step at a time.  I'm sure there are others that could learn from your expertise.  What's the best replacement and where do I buy it?  I only want to do this job once......so......please help me if you can!!!!  Thanks~~~~Ron
By Ted - 18 Years Ago

Best Gasket makes a neoprene rear seal for the 312 and can be obtained through John Mummert.  The Best Gasket number is 3A-52.  Make sure you’ve got a 312 before trying to install a 312 seal though.

 

The seal can be installed with the engine in the car.  Engine may need to be raised up off of the motor mounts and the crank will need to be rotated so that the rear counterweights are up so that the pan can be slipped out.  Having #1 at TDC will get you close.  I like a small amount of RTV in the side seal slots before slipping the side seals in place.  Some copper coat on the torqued surfaced between the engine block and the seal retainer also adds a bit of insurance against a potential leak.

 

Run a search on this site for rear seal replacement as this has been a popular topic in the past.
By DANIEL TINDER - 18 Years Ago
An interesting anecdote:

The old mechanic I deal with (worked at a Ford dealership in the 50s) was changing the rear seal on a '56 312 customer I had referred.  When I dropped by the shop and noticed my friend's car, he informed me there had been a screw-up, and the seal had NOT been ordered.  I then gave him the ph.#s of several suppliers who could overnight the red neoprene 312 seal that was needed (a Godsend apparently, after all the horror stories I have heard over the years about unsuccessfully altered Mopar seals/poor rope installs that ended up leaking).
I returned a couple days later and noticed the '56 was gone.  When I asked about the seal job and who ended up delivering it, he said that since the car had been there so long already, rather than wait for delivery he decided to MAKE ONE!  After I picked my jaw up off the floor, and looked at him like he was crazy, I could see by his expression he had no qualms and was not at all worried.  Could it be that since he knows my friend only puts about 500 mi. a year on his car, he thinks he'll likely be dead when the seal starts to leak? Or is this guy some kind of magician?!!
By PF Arcand - 18 Years Ago
Ted: Are you familiar with what appears to be another new seal offered for the 312s?  It's been mentioned somewhere (in YBM?) and offered thru John Mummerts Ads. It's a Teflon rope seal. Apparently some cranks, due to what I understand is knurling on the seal surface (?) have not had full success with the neoprene rubber seal...    
By Ted - 18 Years Ago
PF Arcand (12/4/2007)
Ted: Are you familiar with what appears to be another new seal offered for the 312s?  It's been mentioned somewhere (in YBM?) and offered thru John Mummerts Ads. It's a Teflon rope seal. Apparently some cranks, due to what I understand is knurling on the seal surface (?) have not had full success with the neoprene rubber seal...    

Paul.  I’m not familiar with the new seal you mentioned.  I see it in John’s ad but there’s no details about it other than it’s listed.  I have so far used the ‘red’ seal without any issues and have plans to use a couple more in the near future.  I must have missed reading about any discussion regarding the teflon seal in the YBM if that's where it was.

By Hoosier Hurricane - 18 Years Ago
Ted:

When I ordered a gasket set from John recently, I asked if the Best set contained the red seal.  He said it came with the new teflon rope, but he would substitute the red one.  He said he has no experience yet with the teflon.

The teflon I'm familiar with has a slow "memory", and if the engine sits for a while, I would think that as the crank settled in the bearings, it would deform the seal a couple thousandths, and upon restarting the engine, the seal would remain deformed for a little while.  Maybe there is a modern teflon compound that has quicker memory, I don't know.

John