Hello,

Trying to tackle a rear main seal leak on my BB. 4.15 Eagle stroker crank with knurling present on the sealing surface.

Two local machine shops (two very well known Mopar engine builders) installed a lip seal. Both leaked. I installed a rope seal, it leaks less but still leaks. I'm 100% sure it is leaking from the rear main seal around the crank and not the side seals or anything else on the rear of the engine. Rear seal cap alignment looks good, I dont believe that the rear main seal cap was machined. Please note I'm using PRO-GRAM billet steel main caps and a chenoweth girdle. The rear main seal cap does not contact the rear main studs.

I always thought that
Knurling = Rope seal
Smooth machine surface = Lip seal

However, the following link shows differently.
Has anyone successfully used a lip seal on a knurled crankshaft with NO leaks??

I'm open to suggestions at this time.

http://www.hughesengines.com/Upload/prod...onsJune2006.pdf

im using a a lip seal with a molnar crank that is knurled with no leaks so far. this is the seal im using. ive had good luck with them
http://www.manciniracing.com/subheporemas.html

It's possible the knurl of the crank is a little aggressive for a lip seal and tearing it up?

Current technology of rope seals sucks, the rope seal that comes with basic gasket seals is rock hard compared to the original rope seals made with asbestos. BEST Gasket has a rope seal that is supposed to be the best replacement available, it's a little spendy ... 25 bucks ... and only available thru Best in Cali.

I put one in my friends 383 with stock crank, it seems to be the only thing not leaking ...

@Runner, Do you remember if the seal you are using came into direct contact with the Knurling on the crank or does it rest on a smooth portion of the crank?

@JohnRR, I'm using an Eagle 4.15 stroke crank. I have heard others state that the knurling finish was to rough/coarse. I'm unsure if mine is to coarse or not. I really dont want to remove the crankshaft, so I'm thinking of resealing it again but unsure if I will try the Superformance lip seal or the Graphtite rope seal.

Make sure the seal retainer is flush with the block. Check it at the top & bottom.

i didnt verify that the seal came in contact with the knurling but id guess it would about have to?
picture

I have a knurled stroker crank that I Fought with for years until I looked closely at the knurl. It is the wrong direction for a car engine. The crank must have started life in a marine counter rotating engine. Might be worth a look.

@Runner, thank you for the picture. It looks like the knurling on your crankshaft is a much finer and shallow compared to the picture I have attached of my eagle crankshaft.

@Ross, thank you for your input, it looks like my knurling is in the correct direction.

I'm suspecting more and more now like others have stated that the eagle crankshaft knurling is too course.

I think you will fight that leak for a long time
unless you pull the crank and put it in a lathe
and polish it a bit with some fine paper to knock
it down some... I know its a PITA

It's probably the retainer. It's nearly ALWAYS the retainer causing the problem

I have heard of this before also. I agree with Mr P as I would pull the crank and polish the knurl down or off. I cant remember how much knurl was on my 440Source crank but I use steel billet caps and it has not leaked any. Ron

i had the same situation,if i had hair i would have pulled it out.i used a seal i got from SUPERFORMANCE on my currant build..it is orange crank seal and blue side seal.it leaked when i put it together but after i reinstalled it no more leaks,not one drop.proper inst. is critical.

When you say you checked retainer alignment how was it done? Hold it up against the crank by pressing in the middle of the retainer. Measure the gaps on the side to block. If they are way off you may need to use RTV instead of the side seals. Now bolt it in. Remeasure it. Did the dimensions change? If so open up the bolt holes. Also since it has aftermarket caps it had to be line bored/honed. You may need to cut the cap surface as the bore may be to big. I would check this 1st before pulling the crank.
Doug

@DVW, I checked the retainer alignment by bolting the retainer in place and checking the retainer to engine block clearance on both sides by eye, I did NOT measure it (I should have, but since the side seals were not leaking I didn't make a measurement).

I believe that you are advising to check this so that the rear main seal is also centered around the crankshaft, is that correct??

The block was line bored because of the caps. How would I determine how much to remove off of the retainer?

@Monte, is this the same direction you were recommending when you stated the retainer is likely the cause?

@All Moparts, If the retainer is the cause of the leak for what ever reason, what seal would use after retainer concern is corrected?

The transmission is out of the car as of now. I really really don't want to pull the engine or the crankshaft out.... But....

One point I left out. This leak is also present with the engine off, engine cold and priming the oil pump.

I used a stock cap with the orange side seals on a Molnar crank.

I used a dab of Permatex Ultra Black on the bottom of the side seals and then run a bead along the edge of the cap inside where it mates to the block after it was installed. It's been completely dry so far.

Are you using some form of sealer between the block and retainer mating surface? This is commonly forgotten about. The picture doesn't show any signs that there was sealant in that small area.

Trendz, Yes I use sealant. In the area you described. The picture I supplied was the lip seal a local engine builder installed.

[quote=B5496RR]@DVW, I checked the retainer alignment by bolting the retainer in place and checking the retainer to engine block clearance on both sides by eye, I did NOT measure it (I should have, but since the side seals were not leaking I didn't make a measurement).

I believe that you are advising to check this so that the rear main seal is also centered around the crankshaft, is that correct??

The block was line bored because of the caps. How would I determine how much to remove off of the retainer?

@Monte, is this the same direction you were recommending when you stated the retainer is likely the cause?

@All Moparts, If the retainer is the cause of the leak for what ever reason, what seal would use after retainer concern is corrected?

The transmission is out of the car as of now. I really really don't want to pull the engine or the crankshaft out.... But.... [/quote
It was my concern that the retainer is being forced off center by the bolt holes or the sides not being centered. I checked a Mancini billet retainer that side to side was off by .100"+
Doug p

Do a search or have someone find the link to thread we just had on this issue. There was a pretty in depth post about how to go about installing the seal and installing retainer, as to NOT having it influence the seal. Will be tough to do in car though. The retainer is FAR from a precision piece and just because it bolts in there and seems centered, means little to nothing. Remember, the seal is what does the sealing to the crank. The retainer should only hold it in the proper place, NOT influence seal in any direction. If it does, it WILL leak. Forget the side seals. Having to drive those in, is asking for a problem. If yours leaks while priming the motor, you likely have a serious alignment issue