Power trim falling

[SkaterRace]

I just got my boat back from the shop and the power trim is "falling". Pretty much when I put it up to trailer and don't lock it in place then is starts to trim down till it is just hanging there. This can't be proper? Can it?

 

[hemi rt]

Both trim or tilt should hold the motor where you stop it at, sounds like you may have a cylinder with an internal leak or a leak from a line.

 

[Chris1956]

Normally on a 1977 Merc 850, that issue is caused by a bad piston seal or a bad control valve. Replacement of the piston seal requires a special tool. There used to be rebuild kits for the trim cylinders.