85 Mercury Black Max 150 Power 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.

 

[Oldsaltydog]

Your motor (pump) simply pumps fluid from one side of the cylinder to the other. If it's pumping, it's working. The scenario you describe is most likely worn out o-rings on the pistons in the cylinders. I'd look for a video on rebuilding the cylinders and look for a rebuilt kit. Not a bad job.

 

[faztbullet]

Replace the manual release valve first..

https://www.amazon.com/Upgraded-Stainless-93929A01-813442A2-Outboards/dp/B08K8HZT1G/ref=asc_df_B08K8HZT1G/?tag=hyprod-20&linkCode=df0&hvadid=663260354062&hvpos=&hvnetw=g&hvrand=10250196000204145118&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9013141&hvtargid=pla-1639141585103&psc=1

 

[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.