Engine Stop Solenoid

Chris1960

New Member
Mar 3, 2008
42
Isle of Wight UK
Boat Info
Sunseeker Portofino 400
40foot sports boat
Engines
2 x CAT 3126 420hp
The engine stop solenoid on my starboard engine stopped working on my last trip out. I have now learnt how to stop the engine manually if this ever happens again.

I now have a new stop solenoid on order from CAT as well as the seal which I am going to keep and try to have it repaired

Has anyone replaced one of these on the CAT 3126 engine and is there anything I should look out for and what should I use to remove the old one, coz I'm sure it will be a b*****d to get off and its also on the outboard side of the stbd engine so space is very limited for a "fatboy" as my wife has started calling me !
 
Chris,

I had a CAT Mechanic replace my starboard stop solenoid on my 3126 and I watched him use a special tool to get it out. It was a tool that basically set into the small holes, grabbed it, and allowed it to be loosened. He said that if you did not have the tool, use a philips screwdriver,place it in one of the of the holes and to gently tap to get it to turn. The risk is that the screwdriver will not have enough bite to get it to turn. In my opinion, I would not use pair of pliers/vice grips on the housing as it may damage it.

FYI, when it was replaced, he did oil the seal and the piston before installing it.

Brian
 
Thanks Brian, its good to have as much info as possible on easy ways to do this next time I am on the boat.
 
Ok, I now have way too much knowledge of the fuel solenoid on my pair of CAT 3126's. Both have gone off line in the past 30 days at one time or another..... Guess what ??? It wasn't the solenoid it was the wiring harness. Take a hot lead (with a 20-30 amp inline fuse in it) from the positive side of your battery and touch it to the hot side of your solenoid. If you hear a loud "click" that is your solenoid working.... And it is a bad wire connection. Next to your transmission case there is a wire connector with at least 6 good size wires running in and out of it. Get an emery board from your wife and a small jewelers screwdriver....sand the connectors shiny and spread the tips of the male connectors apart for better contact, coat with some type of electrical component lube and try it again.... If it doesn't work (and you did get the click w/the hot lead) then start over and do it again. IF you didn't get the click then you will need the tool and CAT sells it to replace your bad solenoid(my CAT guy gave me his for free) Good Luck, Mark
 
Thanks Mark,
New solenoid just turned up today so cant wait to get down there and fit it and see if that solves the problem, if not then I will try your suggestion and see if that makes a difference
Regards Chris
 
Where would find the special tool for the engine stop solenoid?
Thanks Scott
 
Where would find the special tool for the engine stop solenoid?
Thanks Scott
Your Cat dealer but mine turned out to be the 12volt solenoid in the electrical box at the forward end of the engine. I replaced 2 fuel solenoids that I didn't need to.
 
The engine stop solenoid on my starboard engine stopped working on my last trip out. I have now learnt how to stop the engine manually if this ever happens again.

I now have a new stop solenoid on order from CAT as well as the seal which I am going to keep and try to have it repaired

Has anyone replaced one of these on the CAT 3126 engine and is there anything I should look out for and what should I use to remove the old one, coz I'm sure it will be a b*****d to get off and its also on the outboard side of the stbd engine so space is very limited for a "fatboy" as my wife has started calling me !
I think you may have how that solenoid operates backwards. When the solenoid is de-energized the plunger extends using spring force. When it is energized it retracts. Inside the governor is a small lever that when pressed forward (de-energizing the solenoid) it shuts down the fuel. When that lever (it is also spring loaded) moves towards the solenoid the fuel is allowed to flow to the injectors. So, an engine that will not shut down can be three things - that little lever has become disconnected inside the governor, the solenoid is stuck in the retracted (energized) position, or the electrical voltage is not terminated to the solenoid when the key switch is turned off.
The lever in the governor falling off is very rare but it happens.
The solenoid failing in the retracted position almost never happens. That would have to occur due to corrosion or broken spring.
Electrical current continuing to the solenoid when the key switch is turned off is usually a failure of the relay that provides power to the solenoid. That relay is a $20 common Bosch relay you can get from NAPA. If you measure the voltage at the solenoid and are seeing +12V when the key switch is off then the relay needs replacing.
 
It's a good idea to keep a few of these Bosch solenoids on board.

I'm also keeping a fuel solenoid in my spares box

Not to hijack this thread, but wondering out loud; why not use one of these Bosch solenoids to switch my electronics power supply from port batteries to starboard batteries to avoid electronics reset while cranking the port engine?
 

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