I could be corrected on the following, but if I understand correctly, on 312 blocks the later Neoprene seal has been problematic in some cases, apparently due to block casting irregularities. If you link from here to Ted Eaton's site & look up his post on rear seals, it may be of help. Also, Best Gasket now makes a later design rope seal which on the 312s may be the better route. Others on here with more practicle experience, may have further info that would be helpful..      


Paul

Thanks Mr" Charlie for the wise advice. I will check that out before I take the oil pan loose.

First, make sure it is actually the rear main seal.  Leaks can originate from other sources and appear to be the rear main.  Those places include, but are not limited to valve covers, valley pan cover, oil filter, oil pump, rear intake flange bolt holes, rear main seal retainer to oil pan studs, oil galley plugs, cam plug.  Trace the leak and be absolutely sure it is the rear main before you replace the rear main.

Probably the best thing to do is to go to local car shows and find out if there is a "go to" guy for older engines.


Lawrenceville, GA

Hey Guys,
I have a '56 312 Y Block that has a badly leaking rear main seal. Does anyone out there know of a reliable, trustworthy Y Block mechanic in the Savannah, Georgia, Augusta Georgia area who can help me to get this replaced with a new neoprene seal? Any information would be greatly appreciated.