Merc 150hp trim

[Jolendd]

I have just purchased a boat with a 150hp Merc (low hours) and when under power the trim changes on its own, apparantly it was checked by 3 mechanics before I purchased it. It only appears to drop under load - where is the pump usually located? do trim/lift cylinders ever bypass internally?

 

[86RajunCajun]

Re: Merc 150hp trim

if it is being pushed down by the force of load then it is likely the manual relief screw. look around the bottom of the transom bracket for a screw into the main housing. its likely to be a plastic screw.

They have O rings on them and they can leak and allow the engine to drop.

The plug has 3 positions and 3 O rings. 1 is sealed fully, 2 is open internal to allow the motor to drop or be lifted manually but not to leak fluid from the system, and 3 which is open and drain. The O ring that is likely bad on your plug is the open internal pressure relief.

GL

RC

 

[Chris1956]

Re: Merc 150hp trim

There are several types of PTT Units. Tell us what year and number of trim cylinders and we can help.