Rear Main Oil Seal Leaking Again

R

Rich Thomson

Registered User
This is the second Rear Main Oil Seal that is leaking. I had installed a New Rear Oil Pan Gasket when I put the oil pan on the engine while rebuilding it last year. The oil leaks around the crank. Anyone know of a trick or different seal to keep the oil from coming out. I am running 5-30 synthetic oil.

Rich
 
How did the crank shaft look where the seal rides? I know Chicago Rawhide has a speedi-sleeve for our application which might help if the crankshaft surface is a tad rough.

Have you been able to tell if the leak is from where the seal rides on the crank or if it's leaking from the outside as though it wasn't seated properly or was pushed out?

Is your PCV valve working such that you are not noticing excess crankcase pressure?

here is a thread where the sleeves were discussed. Apparently Felpro has one as well.
http://www.sccoa.com/forums/showthread.php?t=56869&highlight=crankshaft+sleeve
 
just pulled mine

I just installed my engine and noticed it leaking also. I pulled the tranny and installed the sleeve this time. The seal I got this time around seemed to be differant than the last one. Cant remember what he said the material was made of... But I got it at Carquest.

I should have sleeved it when I put it in the car the first time...
 
Been dealing with a leaking rear main oil seal since the rebuild. I myself will be installing a sleeve to stop the oil leaking. To post some tech info the 3.8L crankshaft diameter is 3.625" and the Felpro part 16250 is for 3.625" crankshaft diameter with a length of .660"-.680" which is correct since the rear main oil seal runs at .660 from the rear of the crank. When installing the sleeve be sure to tap it about 1/16" past the end of the crank. The installation tool is part # 16300. I found both of these part numbers at Rockauto for about $35 plus shipping.

I found the specs for the speedy sleeves. I see why it would be a problem installing on the crank with it in the engine. You only need .90" to cover the crank sealing surface.

EZdiag.jpg


Part Number A
Shaft Diameter Range B
Width on shaft C
Overall width D
Flange diameter E
Installation depth F

--A-- --B-- --C-- --D-- --E-- --F--
99362 3.622 3.629 0.812 1.000 1.750
99363 3.622 3.629 0.500 0.625 1.750
 
Rich,

I'm on my third rear main seal in the last 20K miles and it still leaks. It's been that way ever since installing the built bottom end. If you find a solution please let me know what you did. I've tried using RTV on the outer edges of the seal and it still leaks. Not sure if mine is leaking from the sealing surface or the outside edge of the seal.

David
 
Has anyone tried simply heating the sleeve first when installing it? Seems to me that would save the cost of a $35 one-time use tool. :cool:

I did something like that with my SC pulley.. just heated it up a bit first in a toaster oven, then it slid completely onto the shaft with zero effort. No air tools, strap wrench, or pulley pusher tool required. :D

But back on the subject, I used the viton seal for my main seal. The crankshaft had no apparent groove, so I didn't install a sleeve. In my circumstance, its held up fine. I still loose some oil, but not near the amount I had before.
 
already tried that

the sleeve is so thin that once it makes contact with anything it loses it heat. I tried heating it up and it wouldnt slip on any easier. I personally just used a rubber hammer and tapped mine on... took some time but it went on without kinking or bending. Like I said the seal I used this time seemed to be made of differant material. I also used RTV on the outside edge of my seal. I will say that with the sleeve in place it certainly makes the fit tighter!!!!!
 
I use plane-jane 10w30. I'm not certain my remaining oil leak is from the rear main.. I have oil on the bottom of the pan and the drip spot seems to be located further forward. I've been too lazy to get out there and find it and frankly... I'm just so happy that replacing the old seal stopped the major oil loss that I haven't been in a hurry to fix anything further. I'm adding maybe a quart every 6 weeks now compared to a quart every 2 weeks.

I do intend to fix the remaining drip as I'd like to remove the drip pan from my driveway. :)
 
I believe it to work but have never personally installed one before. Making an oversized Rear Mail Seal would be better but I cannot find any. Also if your piston rings are not sealing enough the crankcase gets pressurized and will push the oil out. I imagine a few psi would escape into the crankcase on any supercharged engine.

Rich
 
Nope

Nope I wasnt using Synthetic. Guess I will see if this helps out.. Will have it back in tonight now that I got all the bushings for my diff/tranny and U joints for the driveshaft.
 
A speedi-sleeve can be done with the motor in the car and not apart.
you just need to tap in on vary light and make sure it's going on ok then when you have the grove past the end of the crank brake it off like it says to do then make sure there is no sharp edge befor you but the rear main seal in.
I have done this all ready on a SC and it work vary well for a good 10000Miles and counting
 
Well, guess I should have used the speedy sleeve. I didn't feel any groove when I installed the replacement seal, so I thought I was OK; but after 7 months or so, I looked underneath, pulled the rubber flap off, dried everything off, ran the engine for a minute or 2, crawled underneath and sure enough.. drips coming from the main seal :(
 
How do I remove crankshaft repair sleeve for Rear Main Seal

After discovered a bad oil drip after installed my tranny, it appears either I didn't install the Fel Pro 16250 crankshaft repair sleeve properly or the sleeve is too long to allow the rear main seal to fully seat. I'm positive I have the right seal, Fel pro BS40620 (actually it's National 3909, renumbered as a Fel pro). It's leaking oil worse than before the old seal was removed and before the new sleeve was installend. At this point, I just want to back up and punt by removing the sleeve and just putting the new seal in. Any suggestions are much appreciated!

Thanks,
JH
 
Well after reading all of this I'm a bit relieved in a way. My rear main has also been leaking since the build and I thought it was my fault. Now it looks like it's a common problem. I thought it was because I installed the seal after I final torqued the mains and I just didn't get it in right. I'm intending on replacing it when I swap out the clutch next time and I want to be sure it seals. For the time being I quad fold some thick cloth and stuff in the gap at the bottom of the bell housing to soak up the drip, changing it when it gets soaked.

Maybe it's not a leak. Could it just be engine sweat from all that horsepower we're making? :D
 
Mike Puckett said:
Well after reading all of this I'm a bit relieved in a way. My rear main has also been leaking since the build and I thought it was my fault. Now it looks like it's a common problem.
Click to expand...

don't worry, there are still many things you could have or haven't done that lead to it leaking.

If there is wear on the crank end then you'll need a sleeve. If you don't have wear on the crank end and see leaking then there is some other problem.
 
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