Engine Room Air Flap Solenoids

Manual pull cables may work on smaller boats but not when the helm is a longer distance from the ER where cables run won’t work

This is the first step. I've fixed more than a couple shutdown relays by just disassembly, cleaning and reassembly. Since it doesn't work now you've got nothing to lose but a little bit of effort.

https://dieselpro.com/detroit-diese...-23504196-shutdown-solenoid-for-12-volts.html

Also have them for 24v and 32v. They perform the same function you seek.

One would think that the system worked at some point in the past. Are there any surveys in your files indicating there was a previous problem?
Maybe you could increase pull force by adding a pivot and lever, or, add a counterbalance to the flaps?

I think that's a good idea. I'd rather have that then the air compressor and an air system (another system to maintain).

I think that system was designed in reverse of how it should work. I think the solenoids should open the intake when anything in the engine room is powered on. A solenoid would use very little power to hold a spring loaded auto close damper open. The default position should be closed. Many different items could instruct them to open ,Gen sets, engine starts, or just the engine room temperature getting above a set point. Then again ,a fire and all bets are off. They lose power either per instruction/design of fire suppressant system & auto close. Fire melts wires, shorts or breaker kick ,still auto close.

Good thought process. I use the forward flaps for forced air injection into the ER, and the remaining flaps for input/exhaust as needed by air pressure. Whenever any engine system starts the forced air system is energized. That circuit opens all of the flaps, and shut down closes the flaps. We can leave the forced air injection running after shutdown via an override, and that allows the flaps to remain open, heat exhausted. When it comes time to work in the ER we crank up the chilled water air handler dedicated to the space.

The flap system is controlled by 1) a breaker for constant power that energizes a contactor triggering the power. 2) override switch that alternatively energizes the same contactor.