How do you shut down the engine on your m-18 30+?

[light24bulbs]

I've got a new to me 30 plus, and the previous owner told me that to shut down the engine I should pull the knob under the key. I think it's a "compression vent".

I just read the manual, and it says to never do this saying it could damage the exhaust valves, and instead pull back on the throttle to starve the engine of fuel. I tried that and it did nothing.

The previous owner has been stopping the engine with the pull knob for 39 years and the motor is fine. Any advice? Am I wrong about the pull knob being a compression thing?

 

[Dave G.]

My engine model is the 5416 and I pull the throttle back to kill the engine. I don't have a knob under the key so not sure what that is and it may just be a cable to shut off fuel. Most compression release levers do not have a remote control cable for the reasons you state. The compression release lever is generally located on top of the engine right next to the valve cover so I would check to see where that "pull knob" goes on the engine. Does it pull like cable is attached or is it a switch? It is not unusual for diesels to have a separate fuel shut off and most of the older ones were connected to a cable that shut off fuel at the mechanical pump on the engine.

 

[Kenneth K]

The knob under the key is for shutting the engine down. Follow the cable/linkage down to the engine and you'll see that this knob shuts off fuel at the injector pump. The knob must be pushed back in to start the engine. Also nice to know how to move this lever by hand while standing in front of the engine.

A decompression lever does what it describes--stops the valves from sealing. This is used to start a cold engine when using weak batteries--it allows cranking rpms to get high enough for a start. If you open the decompression lever while the engine's running, it overspeeds and likely damages internal parts.

 

[Christian Williams]

instead pull back on the throttle

There's an alternative to the kill cable in which the throttle control at the pedestal is rigged so as to pull back beyond idle, which shuts off fuel flow and stops the engine. A spring is installed so you can feel increasing resistance as the throttle is over-retarded, and when released the throttle returns to idle.

Boats have either the separate kill cable or the throttle-retard system, but probably not both.

 

[light24bulbs]

Thanks, I understand now and I learned something important. Appreciate it.

I REALLY wish the engine manual had a labeled diagram, so thank you Kenneth for that one.