Rear main seal

[Plymouthrocks]

Needing advice
Ok I have a 1968 440 don’t think it has ever been rebuilt and don’t plan on rebuilding as it was running well but anyway I have trans off on stand and at some point will put a new 6 quart pan on I was thinking I might as well change the rear main seal which is not leaking but probably close to 60 years old is this a good idea and is it very difficult? Am I opening a can of worms? Also if you all do suggest to replace any recommendations on the type of/brand of sea best? Thanks ahead of time

 

[dadsbee]

If it ain't leaking, don't make it do so!!

 

[gtx6970]

If it ain't leaking, don't make it do so!!

This,
Dont fix what broke

 

[R413]

Don't even go there. If you are asking if it is difficult that means you never done one.
So if you change it, it will leak, I guarantee it.

Most mopar guys on here can't install a dry rear main.

 

[ruffcut]

If it aint broke, don't fix it! Cause it will be broke!

 

[PurpleBeeper]

Don’t touch it

 

[coloradodave]

Wow! Look! Everybody agrees! Might be the first time on the forum...lol.

 

[Bird 426]

It probably has a rope seal in it. Yeah, leave it alone. Dealing with this right now, just got my new Hemi started two nights ago and have a massive rear main oil leak. Bout had it with the new neoprene/viton seals, use this, do that. My next engine build is gonna be back to rope.

 

[dvw]

Personally I've never had a rear main leak. Built quite a few engines. Mopar, Chevy, Ford, Olds. It's amazing how many fresh builds I see leak. Done right stuff seldom leaks.
Doug

 

[Dan64]

Chris Birdsong on You Tube did a video on this not to long ago. Seems as though a lot of 440 blocks have a machining misalignment that puts the crank side shifted on the seal ( pushing hard on one side and not enough surface tension on the other side to seal(. The fix was to go back to using a rope seal that will tolerate this misalignment and actually seal as it should. He also noted that he hadn't seen this problem on 383, 400 blocks only on some 440 blocks.

 

[Dan64]

I'll add , it can be entertaining to see which leaves a bigger/ faster puddle on your garage floor, engine oil or fluid from your 727. You can race anything.

 

[Bird 426]

Ha! Have both on my build, ATF for the win!

 

[dvw]

Chris Birdsong on You Tube did a video on this not to long ago. Seems as though a lot of 440 blocks have a machining misalignment that puts the crank side shifted on the seal ( pushing hard on one side and not enough surface tension on the other side to seal(. The fix was to go back to using a rope seal that will tolerate this misalignment and actually seal as it should. He also noted that he hadn't seen this problem on 383, 400 blocks only on some 440 blocks.

The fix is drill the retainer holes a 1/64 oversize. Then let the seal finds it's own center. Easy if you offset the seal halves a 1/4" or so. Then fill the sides with good quality RTV (Ultra Grey never leaks). A little anaerobic sealer between the retainer and block will prevent any seepage at that joint. If the bolt bosses for the pan bolts are cracked? Use studs or seal those pan bolts with Teflon paste.
Doug

 

[RemCharger]

Mock+ check first. Then on final assembly torque down and let it find its home. THEN do your side seals, if using them.. on this one I had to do some trimming to adjust for the retainer not being equal side to side

 

[Bird 426]

#13. Going to try that. Similarly suggested by Rick S. It's just a bitch doing it in the car. Wasted my money on that trick Mancini seal cap, I just wasn't paying attention. Will see how this goes, letting it drip dry till my temper cools.
Thank you!