[MB] Solenoid Operated Bypass Valve

[lancerolson]

I have a sailboat with hydraulic steering and an Autohelm 7000 autopilot. Instead of a reversing hydraulic pump, the previous owner chose to install a mechanical linear drive with a separate, dedicated tiller arm. The attachment shows the layout.

A solenoid operated bypass valve is fitted close to the hydraulic ram which appears to be a 2 way/2 position valve in the normally closed position. The autopilot works correctly when the drive unit is detached from the tiller arm but when attached it tries but fails to move the rudder. I'm assuming that the bypass valve is failing to open and this is why the drive cannot move the rudder.

I planned to replace the valve and searched the Raymarine manuals to find a recommended part number. In the Hydraulic Pump Installation Guide (Doc#81178-5, p.18) I found a different but similar situation which recommended bypass valve M81167. This appears to be a 4 way/3 position valve typically used with continuously operating pump and does not look suitable for my application or the one in the manual referenced above.

Does Raymarine have a 2 way/2 position valve for my application or am I best off with a third party product.

Thanks, Lance