Trim problem

[Vinnys]

Trim only goes down under load.
I have a 1996 Volvo Penta DPS drive.
At the dock, idle speed and to about 8 mph the trim works perfect.
Once on plane the drive will only go down, no up trim.
Fluid is still clear with no foam and to its proper level.
No slick behind boat when she sits and I run her up and down
New seals on cylinders 3 seasons, 156 hours
New pump body 3 seasons, 156 hours
Original electric motor and harness, many hours

Thanks in advance

 

[dypcdiver]

Sounds as if either the piston seals are failing or there is a problem with the pump, possibly debris stuck in a valve etc.

 

[Vinnys]

Been a while. Boat went in very late this year. 2 weeks ago.
The problem with trim still the same.
The Actuators were not leaking. The seals are fine.
Bench tested the pump. Cleaned valves.

Any body?

My next step is to bring to a hydraulic shop local.

Vinny

 

[dypcdiver]

Did you replace the piston seals 3 years ago because of this problem? Does the trim alter of its own accord when under power?
You say you replaced the pump body, do you mean the mechanical part or the motor part? Was it an original ie. Volvo Penta part?
Sorry for all the questions but, is sounding like a lack of power or pressure. Have you tried holding in the over-ride button in whilst trimming up as the control of trim is related to the trim sensor?