Power Steering mystery - This shouldn't work but it does

[Mikehp0]

I had reason to run my Prestige 38s Zen Dog on just the PORT Cummins QSD 4.2 engine for half an hour on Sunday. Not a problem - I have a bow and stern thruster so marina maneuvering in moderate winds is straightforward. As expected, no power steering - I've always understood that my boat's bravo 3 legs get power assistance only from the STARBOARD engine (I've corrected this - thanks for spotting my error Portofino) . But, at one point, I switched on the stopped starboard engine's ignition. I definitely didn't start the engine. I had power steering. How? I switched off the starboard engine ignition - no power steering. I tried again - same result - the power assistance came back on. Both engines have a power steering pump on the front and both are plumbed into the dark recesses where the steering rack lies. Surely there's not some sort of electronically activated changeover valve, is there?

 

[Portofino]

You say the port engine runs the PS and was running all the time with PS .

 

[Portofino]

You say the port engine runs the PS and was running all the time with PS .

 

[Mikehp0]

Thought I'd do what I've encouraged customers to do over the years - RTFM! Screen grab attached. How useless... "Steering is obtained through rotation of the Z-Drive housings", apparently. It encourages me to "learn how to judge the necessary distance of deceleration for the vessel to come to a complete stop - The reverse gear is not a brake". So that's where I've been going wrong! No help with my mystery though!

 

[Mikehp0]

You say the port engine runs the PS and was running all the time with PS .

No - sorry - port engine was running as normal but gave no power steering assistance as expected. My understanding is that the power steering pump is only connected on the starboard engine which wasn't running. Switching the starboard engine's ignition back on (but definitely not starting it) gave me full power steering!

 

[Mikehp0]

You say the port engine runs the PS and was running all the time with PS .

Sorry - have corrected original post - port engine was running. Starboard stopped. starboard engine alone gives power steering (or so I thought)

 

[Chris_d]

Electric power steering pump? Fairly normal on cars these days.

 

[Mikehp0]

Electric power steering pump? Fairly normal on cars these days.

Hi Chris. Thank- I wondered that too. Everyone I’ve asked says no, though. When next on the boat will try ignition only - no running engines. If I have power steering then, I’ve definitely got an electric pump.