Yanmar stop switch

[Ziggy]

So this spring I started my Yanmar 3Ym20 diesel for the first time after the long Maine winter hibernation. It started instantly and all was well until I pressed the stop switch. Nothing happened and the engine kept merrily running. I had to look up the stop solenoid location in the manual to finally stop it. Inspection of the pushbutton stop switch revealed that one of the spade terminals was badly corroded. However, cleaning it did not remedy the problem: with the switch closed, the resistance across the terminals was still very high. So apparently there is also corrosion inside and I could not see any obvious way to non-destructively open the switch to clean its innards.



So I check my friendly Yanmar parts distributor's web site and find they have the stop switch for 3YM20 in stock for $128.76 plus shipping! The stop switch for 4JHE is "only" $30.29--still outrageous for a simple pushbutton switch in a rubber boot, but a lot more in line with what I expected to pay for a Yanmar part.


I can probably eventually find a substitute that fits the same panel opening, but I find the Yanmar price truly outrageous. By the way, my switch failed after only 11 years of summer sailing (the boat is normally shrink wrapped in winter.)

[gamayun]

Ok, this is maybe a dumb comment but I've never been shy about this in the past so here goes. My engine is a Yanmar 3GM30, which has a cable pull for a stop switch. Much easier and simpler, in my opinion, to troubleshoot. Seems a push button kill switch is a bit more "technically" involved from an electrical standpoint. I'm pretty sure mine has been working the past 30 years with zero effort on my part (though I have read that the cable should be oiled annually). Maybe this is a possible solution...

[MartinR]

You will find an non-Yanmar switch that fits the panel. But make sure it is rated for the Amps.

[Compass790]

Originally Posted by Ziggy

So this spring I started my Yanmar 3Ym20 diesel for the first time after the long Maine winter hibernation. It started instantly and all was well until I pressed the stop switch. Nothing happened and the engine kept merrily running. I had to look up the stop solenoid location in the manual to finally stop it. Inspection of the pushbutton stop switch revealed that one of the spade terminals was badly corroded. However, cleaning it did not remedy the problem: with the switch closed, the resistance across the terminals was still very high. So apparently there is also corrosion inside and I could not see any obvious way to non-destructively open the switch to clean its innards.



So I check my friendly Yanmar parts distributor's web site and find they have the stop switch for 3YM20 in stock for $128.76 plus shipping! The stop switch for 4JHE is "only" $30.29--still outrageous for a simple pushbutton switch in a rubber boot, but a lot more in line with what I expected to pay for a Yanmar part.


I can probably eventually find a substitute that fits the same panel opening, but I find the Yanmar price truly outrageous. By the way, my switch failed after only 11 years of summer sailing (the boat is normally shrink wrapped in winter.)

Welcome to to the world of Yanmar. They'll sell you an engine at a reasonable price & then give you a good reaming for parts. Just count yourself lucky that you are not in New Zealand, yanmar parts prices are double the USA cost.
If you are adaptable I'd go with what either post #2 or #3 says.
If i could afford a new engine it would be Kubota based, definitely wouldnt buy Yanmar

[Ziggy]

Originally Posted by gamayun

Ok, this is maybe a dumb comment but I've never been shy about this in the past so here goes. My engine is a Yanmar 3GM30, which has a cable pull for a stop switch. Much easier and simpler, in my opinion, to troubleshoot. Seems a push button kill switch is a bit more "technically" involved from an electrical standpoint. I'm pretty sure mine has been working the past 30 years with zero effort on my part (though I have read that the cable should be oiled annually). Maybe this is a possible solution...

I'm sure it's possible to fit a mechanical cable to the stop solenoid, but for my engine it would need to be "push" not "pull". It would also involve drilling another hole in the cockpit (which I generally hate to do) and assorted other bits and pieces. Overall does not seem much simpler than a single pole momentary switch.

[Ziggy]

Originally Posted by MartinR

You will find an non-Yanmar switch that fits the panel. But make sure it is rated for the Amps.

The panel has a 3A fuse, so I assume any switch rated for more than 3A would be OK.

[Privilege]

This kind if thing is a problem on many panels including the Yanmars. The panel wires are so small coming from the panel that after a while they become slightly corroded and just cannot conduct sufficient current to activate the solenoid start motor and/or the stop solenoid. To see if this is the problem, take a wire which is connected to 12v and connect the + to the stop solenoid +. My guess is that you'll find that it will activate straight away. If it does, your wires from the panel are likely the problem.

The same problem occurs with the start motor. This is what I did to fix mine. I used a $5 relay and although some people on the site may advise against this, it fixed the problem straight away and has been fine ever since.

[Ziggy]

Originally Posted by Privilege

This kind if thing is a problem on many panels including the Yanmars. The panel wires are so small coming from the panel that after a while they become slightly corroded and just cannot conduct sufficient current to activate the solenoid start motor and/or the stop solenoid. To see if this is the problem, take a wire which is connected to 12v and connect the + to the stop solenoid +. My guess is that you'll find that it will activate straight away. If it does, your wires from the panel are likely the problem.

The same problem occurs with the start motor. This is what I did to fix mine. I used a $5 relay and although some people on the site may advise against this, it fixed the problem straight away and has been fine ever since.

That's a good suggestion. However, in my case, the original Yanmar wiring already has a relay between the stop switch and the solenoid. The wiring looks OK. But the switch resistance looks over 3 Mohms when closed, so that seems to be the problem. The push button is covered with a rubber boot, but there is a tiny opening where the body penetrates the panel, so I think water can get inside and wreak corrosion havoc. For the price they charge for it, I would expect much better effort at making it waterproof.


If you have a Yanmar Type B panel in the cockpit, I would suggest putting it inside a sealed plastic enclosure.