what causes rear seal failure

[superpop]

I have a 96 VP 4.3L and I am in the process of pulling the motor to change the rear main seal as it is leaking pretty good. What causes this seal to wear out. The motor was replaced in 99 and I don't want to pull it again. Any other gaskets I should change while I have it out or anything else I should do while I have it out. Thanks.

 

[Don S]

Re: what causes rear seal failure

If water (salt water especailly) gets into the flywheel housing by whatever means, it gets on the crankshaft end. Which gets rusty. That rusty section acts like sandpaper and wears out the seal very quickly.
When you pull the engine, look at the pan. If it's really rusty, as in flaky rust, replace it and the pan gasket. Then find out why there is so much water in your bilge that everything is that rusty.
Small volume automatic bilge pumps with small short hoses exiting the boat keeps the water from getting too high in the bilge and getting into the flywheel (aka Bellhousing) of the engine. While it may not look deep when stopped, imagine how deep it is when trying to get on plane when the bow is the highest.