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shuffster
07-12-2007, 02:23 AM
"I recently built up an auto engine(Ford) 351w into a marine engine for my Century wood boat. The engine runs great, but I have been fighting a leaking rear main seal.
I realize that I should have used the proper crank, but didn't. I did use the reverse rotation seal (two piece). This lasted for only 10 to 15 hours before the leak was substantial.
On tare down, I found much of the seal rubber had transferred to the journal.
This is an early block, probably had a rope seal. I have read that some of these blocks had poor concentricity at the rear main seal, and the original rope seal worked well, but many times if replaced with the neoprene seal it could have problems.

Any suggesstions??- I have looked at both reverse and standard seals and they look and measure the same. One is $15 and the other much more. There is also a high performance seal made out of a better elastomer for racing applications. I am thinking of going to a rope seal as a fix. I hate to change out the crank.

Any help would be appreciated."

sledderdoc
07-25-2007, 02:20 PM
Dave I believe the proper crank is crucial in a reverse rotation engine as a normal one would actually throw oil at the seal rather than directing it away as it would in normal rotation. The result is a leaky rear seal. I would replace it with the correct part.