Lower helm steering does not work but autopilot does - any ideas?

[Looking Glass]

The lower helm steering does absolutely nothing, just spins. The upper helm is fine and i can steer with the autopilot as well. It happened suddenly with no prior issues. At first I thought the autopilot was not disengaging but i turned it off and it did not help.

I do not see any physical problems, such as leaks.

Any ideas?

 

[Pascal]

Usually the upper helm is the one loosing pressure first, then the lower helm. The AP is often the last to work as the pump is typically down low. Some systems have valves to isolate each helm or pump, did you check that?

 

[Fanfare]

The fluid in your steering reservoir is still about an inch from the top? Your air pressure gauge should be showing 20-30 psi. Be sure it drops when you open the tank to check. Sometimes the gauge gets stuck and gives an incorrect reading.

If I have to reprime my steering I open the bypass valve near the stern steering ram, then turn each helm 100 turns to the right, then 100 to the left to get the fluid all the way around the system. I do this starting with the lowest steering pump, the autopilot in my boat. Then the lower helm, lastly the fly bridge helm. The whole system has to be purged of air. Remember to close the bypass when finished.

 

[Looking Glass]

I checked the air pressure and it was low, 8psi, so I raised it to 30psi. The fluid level is good. However, the lower helm still does not work.

Pascal, there are valves to isolate each, but they haven't been touched.

 

[Boatsb]

Now lets look at physics.

The system is air over hydraulic therefore air pressure in the tank causes the hydraulic fluid to rise to the helm. If the lower helm is not working it could be it's non functional if the valves are open. Crack a line and see if there's fluid at the lower helm. It could have been shut off or bypassed by accident. Or it could be a problem I. The helm as I stated.

 

[Looking Glass]

Thank you for all the responses.

After a few hours the lower helm started working. I guess it took sometime for the added air pressure to take affect. I plan to bleed the lines when I return to my home port to make sure there is no air in them.