Alpha 1 Gen2 Trim drops when under power

[Nitz31]

'09 Merc 5.0L w/ Alpha 1 Gen2 - trim works fine up and down, but when I'm out on the water and trim the motor up it drops right back to the down position. Occasionally, it stays slightly above the bottom position but then often it will drop to the full down position? No luck researching this on the webs so far. Anyone have any experience with this? I was told a possible bad check valve in the pump? All fluids are good and no fluid around the rams; boat is currently in the water.

 

[alldodge]

Yes problem is inside the pump, check valve most probable cause, but could be the shuttle valve

 

[Bt Doctur]

or worn O rings in the cylinders

 

[Nitz31]

or worn O rings in the cylinders

Thanks. I just bought a new pump and will see if that solves it. If not, I'll rebuild the cylinders. That doesn't look too difficult.

 

[Scott Danforth]

I would pressure check prior to buying parts.