A friend of mines outdrive is leaking down overnite. Any ideas what would cause this. I didn't know what ot tell him.It's a bravo 1 on a 28' crackmate, I mean checkmate.

Bad seal?? Where is it leaking???

teh easiest test to preform is unhooking the lines that go to the trim clyinders at the bottom of the transom plate. Then get some couplers and loop then to themselves. If it still leaks down, the clyinders are bypassing internally and need to be rebuilt. If it holds this way the problem is the trim pump.