View Full Version : 20R Front Main Seal

09-07-2008, 06:38 PM
Hey Mark,

I'm changing the front main seal on a 20R motor in a 1980 4x4 Truck. People say that if the seal is old, it will wear a groove in the crankshaft so getting a thinner seal is best so that it seals on an un-grooved part of the crank.

What engine/car will have a seal that will work?



P.S. Also, any idea what other seals commonly leak on this engine other than the valve cover (already doing that too)? Thanks

09-08-2008, 10:16 AM
Use the late model 22RE seal (pn 90311-45014). It changes where the seal rides on the pulley so that you're running on a new surface. I'd go ahead and replace the oil pump o-ring while I'm there. As for leaks...oil pans are pretty common on the 20R, especially around the drain plug area, but outside of that they were a pretty good oil retainer. Leaky valve covers are due to substandard parts (Felpro for instance) or just being on there tooooo long.

Main Seal $11.47
Oil Pump O-Ring $8.08


Road Ripper
09-11-2008, 06:20 AM
My dad used to have an '80 4X4 truck too. The distributor O-ring got hard with age and leaked, so you may want to check/replace that, too.

Thanks for that info on the front seal, Mark!

09-11-2008, 02:37 PM
NP...and yes, Distributor O-rings can go bad, but not nearly as often as front main seals do on this particular application.