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Discussion Starter #1 (Edited)
Wrapping up my engine build. Installing the flywheel/clutch/bell/etc. 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 don't see any groove or scratches or anything really indicating a bad sealing surface. But, the previous seal was leaking a little. Should i install the sleeve? Any downside to installing the sleeve if it wasn't needed?
 

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yes i would based on your previous experience with it.. if you hadnt provided the background i would have said no...
 

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Anything over 100k with a leaky rear main will most likely need a sleeve. They’re kind off a pita to tap in though since they’re so thin.
 

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Discussion Starter #4
Does any sort of sealer go between the sleeve and crank or just wipe some oil on and tap it home?
 

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If I remember correctly I just put a little grease on and tapped it in. It was pretty damn tight to get around the crank, but the new rear main sealed nicely.

I can’t imagine a little sealer would hurt.
 

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I wouldn't use a sleeve. I've seen them leak even more after installing. The problem is they don't make a seal for a sleeve. So it puts more pressure on the inner seal itself. Now if you want to fix the leak the right way. Use a teflon seal. Felpro makes one it's in their parts catalog. The difference is the teflon seal contacts the entire rear surface of the crank vs a 3/16 spot on the crank. When installing a teflon seal do not lube at all. Goes on dry. I have been installing them since the late 80's at the ford dealer and still using them. Sleeves are a band aid that doesn't like rpms and will leak 9 out of 10 times.
 

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ive never used one of the teflon seals on a ford.. but literally it was the only thing that would seal on a few chevy motors i had.. so it has my vote... If you use a seal saver use lock tight to seal it.
 

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Yes you use loctite to seal a sleeve or it leaks in between the sleeve and crank. In the diesel world they make seals and will ask by application if you have a sleeve or not. One seal will not work with the other. In gas engines no such listing. I have taken off plenty of sleeves cause they never seem to work as intended. I'm at my shop right now I have the felpro master catalog. Same teflon seal ford racing use to sale. Works very well. I will get you the part #
 

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Forgive me but when I pull up that p/n this comes up from summit. It suggests it’s rubber. Is there a Teflon version or is this mislabeled. ???
 

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So many rear mains replaced mistaken for ****ty oil pans (read: canton) and elevated crankcase pressure on tired engines. That excess crankcase pressure will find the path of least resistance like water and electricity and this is the rear main.
 

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Good point. Thanks for sharing that!
 

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So many rear mains replaced mistaken for ****ty oil pans (read: canton) and elevated crankcase pressure on tired engines. That excess crankcase pressure will find the path of least resistance like water and electricity and this is the rear main.
The last one I replaced was actually somewhat loose without the sleeve.
Rock Auto has it, it is described as PTFE rubber so it sounds like it is both teflon and rubber.
Honestly, I like the rubber ones just as good.
 
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