Rear main seal help

[mabbore]

I pulled out my transmission to have it rebuilt due to a reverse clutch explosion, lol and noticed that my rear main was leaking a little. I had noticed some oil in my bilge but the boat is an 1987 and figured no big deal. I would alwasy top off from time to time, but never more than a quart over 20 hours. (I put on almost 200 last year). Has anyone replaced this seal? How do I know if the engine is standard or reverse rotation? do I need a marine specific seal? (skidim has them but they are like 50-90!. I have a 1987 sunsport with a 351 pcm.

[crystal waters]

on your engine is the metal id tag with model number and serial number.
on the model number the second letter should be an "L" for left hand engine rotation which is what PCM was supplying on the 351's back in that year to the best of my understanding.

[wotan2525]

Doesn't need to be marine and the crank rotation shouldn't matter. Good time to do the timing cover gaskets and oil pan gaskets, too.

[Jdm89supra]

not trying to but in here but I just got done with mine it dose mater if it is right or left seal. if you put a right in a left turn it will leak within a couple days of use. this is the problem mine had when I bought it they are made to spin one way

[cadunkle]

Correct, main seals are directional. There are raised lines in them which channel oil back into the crankcase. If using a standard seal on a reverse rotation engine it will channel out out past the seal. Also crankshafts will often have knurling on it, little scratches in the sela area, at an angle to channel oil back into the engine. Rope seals are not directional, but knurling the wrong direction on the crank could result in a leak.