Engine Rear Main Seal: Sleeve or no sleeve

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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I have the old RMS out and about to install a new rear main seal. Just wondering if i should install a sleeve here as well?

I have 100K on the crank/block. I replaced a leaky RMS about 2K miles ago when i did a 5-spd swap. When i pulled the motor a couple months ago, the seak i had previously installed was seeping, but not leaking a whole lot. PCV and other parts are all new, so i don't think i have a crankcase pressure issue on my N/A motor.

Anyway, I have a Ford Racing M-6701-B302 seal, which i believe is OEM since the seal itself has an F1SE part number on it.

I also have a Felpro 21-2100 crank seal, and the Felpro 16300 sleeve install tool.

I've inspected the crank the best i can, and possibly see a wear groove around the circumference. But, the previous seal was leaking a little. Should i install the sleeve? Any downside to installing the sleeve if it wasn't needed? I read it scored the crank, so you will always need to use a sleeve on it.
 
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John Dirks Jr

there is enough sticking out to grab on to
Jun 28, 2013
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Could have been leaking from the surfaces where the main cap meets the block. Have you considered that?
 

Wayne Waldrep

Before I post a pic, do you have one of yours?
15 Year Member
Apr 14, 2003
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I learned on the balancer that it only takes a very minor groove to cause a leak. It doesn't even have to look like much. I also think the tolerances in the crank surface and seal both could use the sleeve thickness to make up any differences that might add up.
That's just my thoughts. I've never used one but like I mentioned to ya, I'd like to do this very thing to mine at some point.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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i Can definitely see a wear groove. I can’t feel it, but you can see where the seal rode.

I’ll sleeve it. The last seal didnt seal do why not?

Next time I do this will be on a new 347 bottom end...if I ever do this again
 
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Wayne Waldrep

Before I post a pic, do you have one of yours?
15 Year Member
Apr 14, 2003
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Cuba, AL
Can you take a pic of the metal sleeve in your hand or something. Every pic online just looks like a rubber band. And any other picture would be great. :nice:
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,964
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I could..but too late. I installed it.

It’s thin, but definitely not a rubber band. With the tool and dead blow hammer it was easy to install

34B48806-7DB1-4DD1-B149-99D00C58DCC8.jpeg
 

Potomus Pete

Gretchen Whitmer is eating at me
Mar 7, 2019
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I have a never ending leak on the rear main seal . Very little info on the forums about the sleeve . I fixed all leaks but this one. Last seal I put on was teflon , and it leaked the same day I started the car. Lets see if its going to leak it probably will leak soon.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,964
10,248
224
Massachusetts
Here are the wear grooves I found on my crank. You can’t feel anything, but at certain angles you can see this.

So I sleeved it. Was easy.

57FD5854-3B20-47AC-BF7C-8475ACD20814.jpeg


This was a couple drops per drive leak. Enough to annoy me, but not enough to justify pulling the trans and fixing until I had the engine out anyway.


New sleeve, seal and pilot Bearing now . Crossing fingers this does the trick
F7D0E56F-2076-41F1-AFE4-55E8922D2FB2.jpeg
 

Blown88GT

Founding Member
Nov 13, 1999
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Palm Beach Gardens, FL
I have a never ending leak on the rear main seal . Very little info on the forums about the sleeve . I fixed all leaks but this one. Last seal I put on was teflon , and it leaked the same day I started the car. Lets see if its going to leak it probably will leak soon.
Mine, too, never ending. Original leaked, replacement leaked.
I need to find someone experienced with these to fix it.
I found some local guys that do nothing but Fox Bodies. Saw some of their work at a car show.
Cobra engine transplant into a 4-eye.
IMG_1762.JPG

IMG_1763.JPG
 
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Shakerhood

15 Year Member
Oct 28, 2004
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Mine leaks too but mainly over the winter while its stored away, once I start driving again in the Spring and Summer it will stop.