85 Mercury Black Max 150 Trim Problem

[DKPZ64]

Need some more help... My power trim works up and down but it will bleed off when I leave it up. When I have my boat in the water the trim will not go up when the motor is under power. When I am going slow it will go up but as soon as I give it throttle it is pushed down. Does this sound like I need to rebuild the trim motor or do I need a new one? Help would be greatly appreciated.

 

[brodmann]

Sounds like the motor is doing it's job, but the seals are leaking inside the cylinders. The pump basicaly pumps fluid from one end of the cylinder to the other end to make a piston go up and down. Watch a utube video on how to take the cylinders apard and replace the O-rings. There are lots of them out there.

 

[QBhoy]

Weird is that it will go up when under throttle !! Are you sure the throttle assembly components aren’t interfering with the trim wiring inside the remote control box ? Or something similar? Any issues with the relay wiring ? Or grounding system ?

 

[DKPZ64]

Thanks for the help guys. I think I got it, To much air in the system. I bled it a few times and it is staying up now. Going back to the lake this week and check it out.