Troubleshooting hydraulic stern thrusters

Our boat has Dickson stern thrusters, two thrusters, powered by a hydraulic pump driven by the Cat 3208 PTO. The thrusters did not work, perhaps due in part to a rusted and leaking filter and loose old belts. While the boat was out of the water I got around to replacing the filter and belts and refilling the reservoir. The thrusters worked when the boat was launched but slowed down and then stopped spinning completely after a few minutes. I have tightened the new belts, topped up the reservoir, and tried again with no luck. I did notice that the light at the stern controls (versus the helm controls where there is no light) no longer lights up as it did when the boat first went back in the water.

My knowledge of the thrusters and how they work is limited and conceptual at best. Other than checking for leaks, what steps can I take to troubleshoot? Is there a bleed valve somewhere to let any additional air out of the system? Is there a typical way these are wired and what should I be checking? I welcome any help and please don't assume I know anything! Thanks!

The light, or lack of, is likely a clue. Your dash switch controls solenoids which switch fluid direction, there may also be an electric clutch at the pump so the pump doesn't run full time. The system has 2 sides hydraulic and electric. The hydraulic side is pretty simple and should be durable. My bet is on the electric side. Time to start doing some detective work.

Do you have any gauges that show the hydraulic pressure in the system?

Sean9c, thanks. That's along the lines of what I'm thinking as well.

Capt.Bill11, there is a gauge but it hasn't moved in a year so I have doubts about its accuracy.

Dickson still has a web site. Why not contact them and ask for a set of installation instructions? That will give you the tool to troubleshoot.

jleonard said:

Dickson still has a web site. Why not contact them and ask for a set of installation instructions? That will give you the tool to troubleshoot.

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Thanks, jleonard. I did contact them but didn't think to ask for the installation instructions. I'll do that.