Rear main seal replacement

[fireguyfire]

I have my transmission out for a rebuild on my 73 challenger. My car has a 383 out of a 70 challenger in it, and I am debating about replacing the rear main seal while it's easy to get at.
Can I replace the rear seal with the engine in the car, and if so does anyone have any tips or tricks on doing it?


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[mopar jack]

Easy to do in the car, done it many times. Only problem with transmission out is how are supporting the engine.

[fireguyfire]

Jack screw on the rear of the engine; the car is up on my 2 post lift and I dropped the tranny out the bottom with my tranny jack; took 15 minutes!


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[Rich G.]

Hardest part is taking the oil pan out. Remove the rear main cap, take a small punch and tap the seal that's in the block in so it starts to walk around the crank. Don't hit the crank with the punch. Should walk right out . Oil up the new one and reverse the process. I don't put them in flush but go in a little more so the ends are not flush with the block. Do the opposite on the main cap. Just be sure you have both seal lips facing the right direction.

[fireguyfire]

Perfect, thanks!
I have the steering linkage and sway bar out of the car too so dropping the oil pan will be a piece of cake

[RUNCHARGER]

Easy job right now actually.

[Racer57]

I used this seal on my 383 and was really happy with it.
http://www.fastfishautoparts.com/Performance-Engine-Seals.html

[fireguyfire]

Just about to change my rear main with the engine in my car, on my lift.
A couple of questions; when I slide the seal half around the crankshaft on the engine side, does it just go in dry? A lot of stuff I've read recommends using a thin bit of silicone on the side of the seal opposite the lip to seal it into the block groove, and the seal cap groove, but my thinking is if I put silicone on that face it will all strip off anyway as I slide the seal around.
A master mechanic buddy of mine suggested to loosen the crank caps bolts to make it easier to install around the crank; he's had issues in the past with seal halves binding and tearing as you rotate them in around the crank.
Anyone have any experience or suggestions with doing any of these things?


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[BFM_Cuda]

I wouldn't put any silicone on the seal, just lube it with engine oil and slide it in. It is a little oversize and the two halves will squeeze together when you tighten the retainer cap down.
I would not loosen the cap bolts to put it in. Just be careful sliding the new seal in, as its easy to cut it against the engine block edge. Some kits supply a "shoe horn" kinda thing to help it slide past the engine block edge. You just need to watch that the small hump on the outside of the new seal doesn't get damaged as you are sliding it in.

[fireguyfire]

Great info; my seal kit did come with a shoehorn. How exactly is that supposed to help with getting the seal in?


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[BFM_Cuda]

Great info; my seal kit did come with a shoehorn. How exactly is that supposed to help with getting the seal in?

fireguy, the shoehorn goes between the outside of the seal and the the edge of the block, so as you slide the seal around the crank, the shoehorn is guiding the seal past the edge of the block.

[fireguyfire]

Got it; thanks!


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[fireguyfire]

One more question; when you oil the seal to slide it in, do you oil the block channel side as well?


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[BFM_Cuda]

One more question; when you oil the seal to slide it in, do you oil the block channel side as well?

Yes, I lube the entire seal & channel to help slide it in. Once fully installed, the seal takes on an "o-ring" type seal in the block, so oil all the way around is best, in my opinion.

[Chryco Psycho]

I usually offset the end of the seal 10* or so that way the end of the seal is not quite flush with the parting line on the block