I want to talk about Rear Main Seals (rear crank seal)

Matt01

New member
Hey,

So I've been researching it, and I know we're a few mechanics on the forum. I would like some opinions.

Backstory:
On my 1989 Ford 2.3L I dropped the transmission at school, I purchased what everyone said was the "best" gasket, which is a PTFE (teflon) FelPro #BS40644. This gasket comes with the plastic install sleeve.

One of my teachers was positive it was installed with the lip facing toward the flywheel, I was unsure, but he was an experienced mechanic, so I did it. I know the lip + spring type seals the lip is always facing toward the engine. The PTFE type goes on dry and the other type gets lubed.

The seal leaked, so I put a die in the oil, ran the car, pulled the transmission again and it was lit up like a hotel room on 60 minutes.

So now I changed it with a fel pro lip and spring type seal, #BS40620. I ran the car again, and pulled the transmission to see if it had been leaking, it looked like some seepage just at the bottom, but the gasket was not sit in perfectly, so we adjusted that, and I reassembled everything.. Fully this time, reinstalled it all.

Im thinking though, while I still have the car at school, should I have used a different kind of gasket, like an SKF or a Timken? Maybe a OEM if it still available at Ford (probably not, Fords gay with that).

Did I install that PTFE seal (which is the "best") backwards?
What is the best brand name for rear main seals? Ive read bad stuff about FelPro RMS (which is national)

Thanks
 
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probably you have damaged on crankshaft caused leak of seal. if you can find a ridge on crankshaft and feel it with nail you need to polish crank surface or install a speedy sleeve for sure seal run on a fully flat surface
 
I'd just install the speedy sleeve and PTFE seal. The deals need to be put in 100% straight, get a piece of abs pipe in the correct diameter and use that to install the seal. To slide the lip of the seal over the crank use a small very screwdriver with some oil.
 
I'd just install the speedy sleeve and PTFE seal. The deals need to be put in 100% straight, get a piece of abs pipe in the correct diameter and use that to install the seal. To slide the lip of the seal over the crank use a small very screwdriver with some oil.

PTFE seals need to be used dry. Like I asked, which way does the PTFE seal install?
 
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