I'm helping My buddy rebuild his 312 in his 1955 Crown Victoria, he was wondering if there  is a fix for the  leaking rear main seal?
Is there  a one piece seal like the  newer 302 uses that could be adapted to the Y block? He is tired of spots on his driveway were the  car sits.

Because of the flange design, there is no way to adapt a one piece seal.

The first thing to do is to make sure that it is re rear main and not some other leak.  Other sources are the valley pan, valve covers, rear intake flange holes, oil filter, oil pump, oil pan, oil pan studs in the seal retainer, cam plug, oil galley plugs and possibly others I'm not thinking of right now.  Many of those can drip in a way that appears to be the rear main when it is not.


Lawrenceville, GA

When I rebuilt my motor last summer, I installed a neoprene seal according to Ted's instruction on this forum.  The directions on the package were wrong. I thought I had a rear seal leak as the floor in my garage was always spotted with oil.  Eventually, I found I was losing about a quart of oil every two weeks.  Upon further inspection, I found a leaky oil pump.  I fixed the pump and no more leaks.  Rear seals get blamed for everything. 

Beyond what helpful articles you find on installing the seal correctly, I would think that a good PCV system would encourage your crankcase pressure to go back towards the intake system and not against your seals. The rear main tends to be weakest link in the block when it comes to oil seal and so whenever you have pressure from the crankcase blowby that is not being routed (or "vacuumed" by a PCV valve) then there is a tendency to find this seal leaking. Ted Eaton, and others, have excellent articles on installing a rear main seal and getting it to keep oil in the crankcase properly.

Daniel Jessup

Loveland, Ohio

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

I have been told that about half the Leaks from rear of Crankshaft Area are in fact the Side Seals . Not the actual Rear Main Seal itself. I just put mine back together with a new Seal. Instead of using the Side Seals I used "The Right Stuff" Sealant. Others have had good results using this Sealant.  You should read the Instructions for replacing rear main Seal Posted by Ted on His Business Website. These Engines dripped from the Time they were new. There have been improvements using the New Neoprene Seals but like everything else careful assembly is the Key. Click on the Link below. His Article on Rear Main for the 312 mentions best Seals "Orange" Seals. Those were discontinued because they were too soft. Do NOT use if You find old Inventory. The proper seals are now Black for the 312.
://www.eatonbalancing.com/blog/2008/09/10/neoprene-rear-seal-installation-for-the-y-and-others/