I am in the process of replacing the rear main seal on my 383 (one piece). I have noticed that the prices run from as low as $15 to almost $100.

Honestly, I am fine paying a premium if it means that it won't leak and will last. Do you guys have any suggestions on which seal I should use based on actual experience?

If so, part numbers would be great. Thanks in advance.

 

Go with a Viton (usually brown) seal. The PTFE seals will cause grooves in the crankshaft over time in my experience - requiring a sleeve eventually. The Viton seals stay soft forever unlike Nitrile. Silicone is too soft and easily damaged.

GD

 

FKM (Viton® if you happen to be a shareholder) can be a good choice, but limit that to 70-A durometer to prolong seal life. The seal design is also important, and a dual lip seal with leafs is a fairly safe choice for the application.

 

GD & Vader I appreciate the responses and have found a Enginetech Viton seal and ordered it (actually 2 in case I screw up the install).

However, they were cheap (no more than the rubber or PTFE) I am not necessarily committed to using those seals. if you can point me to specific brands you have experience with I would still appreciate it (and then may have some extra viton rear main seals if anyone wants them for shipping cost only.

Sorry...I need to read a little better. I will check out the FKM seal. Wait FKM is just the Xerox copy machine (get it) of Viton...

 

the listed seals changed somewhere in the mid '90s. The crank and housing, of course, are the same but the seal was revised. I believe they are the brown multi lip ones, i never bother with searching for teflon.
I just choose a vortec '98 OBS truck when using a parts selector.

 

Rear main seal is installed. I did learn some thing however, if you remove the rear main seal aluminum housing do not install the seal into the housing before re-attaching it to the block. That prevents the Seal from expanding enough to get over the end of the crankshaft and causes the internal spring to pop out. After a couple failed attempts I ended up damaging the rear main seal.

After that I change my tactics and installed the rear main seal housing first and then evenly pressed the rear main seal over the crank shaft and into the retainer. Success!

I’m glad I Purchased two rear main seals...