Hi!

Is it possible to have a mopar engine, be it small block or big block, with a leak free rear main seal?

being 2 piece seals, whenever I build an engine they always leak some.

Ive had some engines that leak very little, like I can see just a drop running down the oil pan....

but on some others I can see them leaving a small puddle whenever they get parked for a few weeks on a given spot.

IS THERE ANY WAY TO ACHIEVE A ZERO LEAK REAR MAIN SEAL ON THESE OLD MOPARS?????

I have managed to have my small blocks leak just about everywhere else but with rear main seals I have been good, no leaks.

Yep easy fix, it's called a vac pump. As soon as my engine starts it's under vacuum. 5" @ idle & 10" at full noise. No leaks on my engine since I installed one of these pieces n we even go faster with it too.

on big blocks I wipe a small thin layer of " the right stuff" between the 2 lip pieces and between the block and the small sticks. I usually take my finger and spread it out and seal it up. Birdtracker

The answer is yes and it would be a 440 inch small block. 👌

Yes. none of my 3 leak a drop.
Doug

ive had no luck then.

OK to those who claim that they build engines with perfectly leak free rear main seals....spill the beans....how do u guys do it.

I have never had one leak there.

Mine is dry with Superformance main seal and Mancini billet retainer. Greg has explained many times on here about how to install a rear main without leaking. I install mine on a slight offset and make sure the retainer is centered in the saddle.
I opened up the holes slightly so when I slid it into place it was centered around the journal. Just make sure your pan is seated on the rear pan rail and not raised up on the studs.
I once thought my rear main was leaking but it was the pan and windage tray raised off the rear pan rail by the ARP studs.
Gus

no leak here, used "the right stuff" in seal lips and side seals.....use a quality grease or moly lube on the seal itself to prevent it from burning up on start up

Ditto.

Mine doesn't leak a drop.

I put the crank seals in slightly offset, put some oil in the crank first to keep it lubed and use a thin bead of Permatex Ultra Black on the inside where the cap meets the block and on the tips of the side seals.

Well over 2500 miles and lots of dragstrip passes.

Mine only leak under boost lol

Mancini Billet Retainer

Make sure block sides and top where Retainer makes contact is completely clean , and oil free
I used acetone to clean . Same with retainer , oil free where it contacts bock top and sides

Clock the parting line on the seal halves at 12 and 6 - Obviously make sure seal lips are oriented correctly and a little oil on both seal halves to help slide them both around top of crank meeting at 12


Slide the retainer dry over the two studs that Mancini supplies to evenly center both seal halves on the bottom of crank at 6

Even with the Mancini Billet Retainer I used a little Black RTV down the sides in between the o-rings and a dab on top where the o-rings slide in the holes

Double check block making sure it's still clean and oil free

Slide the retainer back again over the studs making sure the o-rings on both sides start evenly and firmly press the retainer in place over the centered seal halves - The rtv with the o-rings will almost act like a lubricant helping you slide the retainer in place against the sides of block

Clean off the excess black rtv

Remove studs making sure the retainer stays centered

Install bolts and torque in place

Zero rtv on any part of the actual seals themselves

Allow 24 hours to dry


Did my 383 this way and a friends brand new rebuilt 383 stroker motor that he had two shops attempt to seal with zero luck


Zero Drips So Far On Both

Yea I liked the idea of drilling the retainer holes a bit larger so you know the retainer and seal will center on the crank journal as I also do that and have had no seal leaks on my 493 thats been in the car since 2011. Ron

This has been discussed here in detail very recently. It's all about how you install it. Personally, I have never had one leak. Do a search and I am sure the threads will come up

do you guys think that the rear main seal can be changed on a big block without removing the crank?

Yes... the seal can be changed w/o removing the crank in chassis if necessary. Drop the pan and drop the retainer. Maybe loosen the main caps a little to let the crank drop slightly. Then work the top part of the seal in place. I did it to change a seal with significant leak installed by an engine builder.

It leaked significantly less after this service... but not completely dry either.

Absolutely
As already pointed out it can be done with minimal effort, use the proepr parts and install them properly and use the correct preventive measures to seal the seal holder up so you end up with a leak free motor from the rear main seal

Once I apply Nitrous Oxide, mine start leaking.