Hello, I'm new on the HAMB. My name is RonTerry and I'm an automotive machinist. I'm looking for an alternative rear main seal for a 302 GMC. Has anyone found a rubber 2 piece or full round seal for these motors? I havez had 2 best gasket seals leak on me and my customer is upset. Any help is appreciated. I'm not blaming g Best gasket, never had one fail before.
I have never personally seen a seal conversion done on one. Jimmy Six needs to chime in on this one as if anyone knows it would be him.
I found this from 2006 by the Inliner's. Topic of discussion with fellas who've been there..... Read through it....bearing measure and the cutting off the gasket straight vs packing the extra material part has merit for sure. https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=12366 Good luck.
Are you sure it's the main seal? I'm.not sure, but Chev 6 cyl of the same era has crankshaft bolt holes for the flywheel that extend though into the crankcase. They need sealer on them. Also gasket sealer between the rear main cap and block.
Drilling a 1/16'' hole at bottom inside of the groove in cap helps. Any type of material other than the black graphite woven rope type does not hold oil. When I do them, I compress both halves into their grooves using the proper size big 3/4 drive socket.
The Inliners article is a good reference for the seals. What I do is listed there. The last one I did for a street engine was-for my sons 302. Even with a PCV system it will give a drip now and then. I used a Best “rope” and installed like said in the Inliners thread shown above. I still believe the same that it must be packed and tight. The hatches need to be in the seal area. The slinger on the crank should keep 99% from even getting to the seal which needs some oil to keep from burning up.
The Jalopy Journal
