I have a problem with one of my drives lowering it self when my boat sits on the lift with the drives in trailer position. I was told that it might be an O-ring in the pump but not it is. I have tjeked for leaks. Any suggestions ?

Cigaretteman

It could be a tilt cylinder with a bad packing.

they are probably the same as my #4 trim cyclinders and they have o rings in them that go bad and let the drive move

That was the answer I was looking for ! Do you know where these O - rings are in the pump ?

Cigaretteman

Try the BAM link they have a schematic of the cylinder.

The O rings he's talking about are in the trim cylinders.
It's relatively common for these to leak when they age. You should be able to get a cylinder rebuild kit. I rebuilt my cylinders with kits.

Not a good idea to leave the drive in trailer position. There is no benefit (unless your slip is so shallow it bumps the bottom) and it:

1) stretches the bellows
2) allows crud to accumulate on the trim ram piston rods

Yes the leak is probably internal in one or both of the cylinders.