Rear Main Seal Leak Fixed !!!

After two seasons of dealing with this leak, I finally fixed it. This leak was bad and we figured it was the Knurl on the Eagle 4.15 crank it is so aggressive as you can see in the pictures.
The rope seal that was installed in the motor was frayed. I was going through a 6 pack of Valvoline VR-1 20W-50 oil a month. had to scrub every inch of the bottom of my car with a green pad and brake cleaner !!!what a mess.
when the reverse band in my 727 decided to take a permanent vacation I figured now would be a good time to address the leak while the trans was out for a freshen up. While doing some research. I came across a thread on the subject on MOPART.COM this engine builder that was pulling his hair out trying to figure this problem out.
Upon reading that the rear main seal area of the block is not machined at the same time as the mains are, and that a lot of the blocks where machines off set by a couple of thousandths to the centerline of the crank. well check this out If you are having a rear main seal leak read this guys thread he lays it out.

http://board.moparts.org/ubbthreads...ar-main-seal-leak-almost-suicidal-update.html
My fix,
Used a Fel-Pro black lip seal, stagger ends with a dot of sealer/ adhesive on both ends, I opened up the factory rear seal retainer bolt holes slightly so I would be able to let the seal center it's self on the seal journal then snugged up the retainer bolts/I could visually see that there was more room on one side of the retainer then the other) then used Loctite 5699 to fill the sides instead of using the fiberboard,pipe cleaner thingies, torque to 30 ft. lbs and silicone the **** out of every possible place oil could try to escape through, even on top of the bosses for the rear main seal retainer bolts, they are open and have herd stories of that being a possible leak point. I even had purchased one of the star wars billet magical retainers I was about to install before reading this engine builders thread.they had used one but had to do a lot of machining to it.
I am glad to report that after about 600 miles there is not a drop of oil on the floor. I have my fingers crossed.

Great! I have been using the neoprene seal, and silicone the heck out of the sides of the seal retainer, bolt bosses, etc, and that has worked great! I like the max oil resistant grey/black silicone.

Nice.

MOPOWER871 said:

even on top of the bosses for the rear main seal retainer bolts, they are open and have herd stories of that being a possible leak point.

Click to expand...

It is a leak point, ask me how I know. Only after you jack the front of the car up, the next day you'll get a drop or two. Then it doesn't leak anymore. I know I didn't put any sealer in the bolt recesses and didn't hear about this area until I had the engine in the car.

I used the directions on the Hughes site and to the letter. It shows you how to center the seal in both directions ect. I used their viton seals also. Not a drop from the seals at all. 440 Source has them also.

http://store.440source.com/Rear-Seal-Caps/products/26/

BTW there is a sticky on this subject...

https://www.forbbodiesonly.com/moparforum/forums/engine-trans-driveline.20/

https://www.forbbodiesonly.com/mopa...-thread-on-rear-main-seal-replacement.127618/

I read them all over the past year, goggle search led me to the one on moparts thanks K

So you're using a lip seal with that knurled crank and it's not leaking? I'm impressed!

I have had 6 BB Mopars and 2 SB Mopars in my life time and have used the same engine builder for all of them. so far and this was the first one that leaked didn't leak on the dino. I know the rule of thumb is knurl = rope, smooth= lip 600 + miles no leaks I'm watching it closely. and I drive this thing a lot. good weather I'll drive it to work, and go to one of the local cruise spots afterwards and on the weekends out both days and nights weather permitting. this car is a good test bed I figure

I am very happy you were able to fix your main leak,
That said,
I have been posting to threads on here and DC.com, for the last 10 years, trying to inform people that the Seal Groove in the block is NOT concentric with the Crank,
and,
that the cure is to offset the seal from the parting line on the offending side, and then use slight pressure on the seal retainer to "drag" the seal over into contact with the crank as you tighten down the Retainer Bolts.

Once again, for anyone assembling...... STOP !
With the Block upside down on the Engine stand, install the upper main bearings and upper main seal half installed flush with the parting lines(block half).
Now set the crank in the Block.
Take a flashlight and inspect to see how "compressed" the Lip on the Main Seal are side to side.
SEE the problem ? Typically the Lip on the seal on one side will be compressed in GOOD contact with the Crank, and, you guessed it.... the other side barely touchs the Crank and will NOT Seal ! (offending side)
Now,
Re-install the Seal 1/4" up from the Parting Line on the "offending" side.... match the other Seal half offset the same amount in the Retainer. Gently wiggle the Retainer down into place so the seal halves mate offset, then before you tighten down the retainer bolts "gently" pry the retainer over dragging the offending side into contact with the Crank, tighten bolts.

Some Blocks are worse than others, but they all exhibit some degree of Seal Groove offset from the Crank centerline.

Great news!

Challenger340's hands on experience diagnosing this problem was a big help with understanding what the hell was really going on with this leak. I have read his posts on this site and others.
Instead of prying the seal retainer over then locking it down to center the seal on the journal, I opened the bolt holes and allowed the seal and retainer to center it's self to the journal then locked it down then sealed the retainer to the block. the end resolve is the same.
Next time the motor comes out for a freshen up i'm going to take a real good look at this when its sitting on the engine stand. doing this job laying on your back with 3,500 lbs Mopar perched 10" from your face. sucks !!