Ideas on installing secondary start/stop switch on Yanmar

[drapem1]

Interested in some ideas or experience installing a secondary (if primary fails) start/stop switch for ignition on a yanmar 4jh4 hte. I have an electronic sensor near the throttle control in cockpit that I believe controls the ignition (start) switch (STOP is a push in button that I believe kills either fuel or air) I have not had any issues for past years, but thinking if some part of that electronic system fails and I can't either start or stop the engine, that would be a problem. Any suggestions on how to hard wire (near or around the engine) a start/stop button just in case? Be kind as I am barely a novice on electrical side of engine functions. I do realize there are ways to stop a diesel engine by cutting fuel or air supply so perhaps it's more about the start function.

[roverhi]

There is no electric ignition on a diesel. They fire from heat generated by compression. Your shut off activates a solenoid that cuts off the fuel. My older Yanmar has a cable that goes to a fuel shut off valve on the engine. By loosening the capture screw for the cable on the valve actuating arm you can manually use the shut off valve. Haven't tried it with the cable connected so don't know whether you have to loosen the cable screw to work the valve. In any case, you should trace down the fuel delivery system and see if there is a valve you can manually actuate and whether you need to disconnect the solenoid to do it. If you want a remote backup might see if you can use the cable.

You can stop a diesel by interrupting the air intake but you have to be careful. There is enough negative pressure at higher rpm to actually break your skin and suck the blood out of you. Do not use any part of your body to block the intake.

The most common engine runaway with a diesel is caused by oil being sucked out of the crankcase because of a wear/part break in a cylinder. The only way to stop the engine will be by blocking the air intake. You'll normally have some kind of air filter on the intake which may have to be removed to kill the engine. Because of the time delay getting to the intake, such an occurrence usually ends disastrously for the engine.

[slug]

Originally Posted by drapem1

Interested in some ideas or experience installing a secondary (if primary fails) start/stop switch for ignition on a yanmar 4jh4 hte. I have an electronic sensor near the throttle control in cockpit that I believe controls the ignition (start) switch (STOP is a push in button that I believe kills either fuel or air) I have not had any issues for past years, but thinking if some part of that electronic system fails and I can't either start or stop the engine, that would be a problem. Any suggestions on how to hard wire (near or around the engine) a start/stop button just in case? Be kind as I am barely a novice on electrical side of engine functions. I do realize there are ways to stop a diesel engine by cutting fuel or air supply so perhaps it's more about the start function.

Ignition ON energizes the start circuit , instruments , glow plugs and stop circuit

start energizes the starter motor

Two start stations are common

Google it and you will probably find a video solution

Folks like a second station because it makes oil changes , winterizing and general engine work easier

[Jim Cate]

The start function can be accomplished with a simple 30+A momentary push button SPST switch wired between the hot terminal on the starter (where the fat cable connects) and the terminal on the solenoid. This switch will activate the starter and, in turn, start the engine. It wil not activate most of the accessories, like tacho, alternator regulator, gages and other ancillary equipment. But t he engine will run!

I'm not familiar with Yanmar engines, but on most engines that have a push button kill switch, it activates a solenoid that pulls on an arm on a fuel shutoff valve. On such engines one can simply push on the arm manually (in the same direction that the solenoid acts) and the engine will stop.

These simple methods have worked on my Kubota based Nanni for many years.

Jim

[sailormed]

On our boat I can start the engine
1 from house bank
2 from start battery
3 with jumper cables

I can stop the engine
1 on Yanmar instrument panel
2 with the BIG RED button on the engine
3 by obstructing air intake

I do not think another system is necessary.
Yanmar has already included a second simple mechanical option for killing the engine!

[drapem1]

Thank you for the many responses! All good ideas and now have several alternatives to check into. Much appreciated!

[Juho]

If you want to shut down the engine without relying on anything electrical, you could simply connect a direct cord/line/cable to the mechanical shut off valve "lever" (the same mechanism that also the electrical shut down mechanism uses).

[bauer965]

I highly recommend a mechanical stop cable if your engine is only controlled by a electric switch for the solenoid. 2 things could fail there, the switch, or the solenoid. They will only fail when you need them to work. Sure, you can reach in and pull the solenoid plunger with your hand, but this adds time and may not be easily accessible depending on circumstances. (I have a back-story hear.) All engines should be fairly easy to be retrofit with an additional mechanical stop cable. It's my primary method, and doesn't need to be expensive - Google "John Deere Stop Cable" (some people will surely scoff that I don't have a "marine" stop cable that costs 10 times more...this has lasted 6 years so far and still looks/performs like new).

The previous recommendation to install a separate start switch in/outside the engine access is also a good one for maintenance and emergency use. I've only had a control panel switch fail once due to poor connectivity. It just delayed my departure about 10 minutes as I took the panel off and cleaned up the terminals/connections and reinstalled the wiring. So not a big deal. However, if this was out at sea and I needed to start the engine ASAP, it may have presented an issue, and cleaning terminals may not be what I feel like doing in certain navigational situations, weather, or sea state.

I once sailed on a non-profit owned boat that got frequent use, and in fact, using the engine compartment start switch became the normal for years since no one wanted to be bothered to fix the switch in the remote panel at the helm...

[Gaia]

I installed an extra start switch in the engine compartment that can only be activated once I open the ball valve I added to the exhaust system. Easy peacy. Now i always start and stop the system from below. That of course has positives and negatives but adding a secondary switch to start the engine is a good idea. Yanmar also undersized their wiring in the starter circuit and adding an extra switch with adequate wiring to prevent voltage drop helps.

Jim

[sailcrazy]

Some years ago I added an electrical "make-break" switch to the power path to the starter for both our main engine (Yanmar 4JH-TE) and genset(Onan 6.5kva). My thought was to have a positive way to kill the power to the starter, if/when it malfunctions and will not stop. Not quite the same as a positive way to stop the engine, but a positive way to kill power to the starter should it fail/hang up. Starter power (for both) comes from a dedicated "start" battery, or from the house bank, then through my "isolation switch", and then to the starter solenoid-all heavy cable. The key/start button only activates the solenoid that connects the power to the starter. Stopping the motor has never been a concern, as I can always cut off the fuel or air manually.

[waterman46]

Originally Posted by Jim Cate

The start function can be accomplished with a simple 30+A momentary push button SPST switch wired between the hot terminal on the starter (where the fat cable connects) and the terminal on the solenoid. This switch will activate the starter and, in turn, start the engine. It wil not activate most of the accessories, like tacho, alternator regulator, gages and other ancillary equipment. But t he engine will run!

I'm not familiar with Yanmar engines, but on most engines that have a push button kill switch, it activates a solenoid that pulls on an arm on a fuel shutoff valve. On such engines one can simply push on the arm manually (in the same direction that the solenoid acts) and the engine will stop.

These simple methods have worked on my Kubota based Nanni for many years.

Jim

And then there's the BIG SPARK method, in which the skilled operator uses a large screwdriver to short circuit between the two terminals on the starter solenoid. Be careful to never touch battery terminal to ground, which is quite nearby!

But in any case, when using these methods you need to be sure your gear shift is in neutral and the engine is in or near idle throttle before starting the engine. The Morse control, and I assume other controls, has a microswitch mounted in the control that is (should be) wired in series with the starter button. The switch only closes when the control is in the neutral gear position. When starting using any other system, you don't get this protection. Been there, done that! Fortunately, at anchor not at dock.

Your keyswitch usually has three positions, OFF, RUN and START. If the circuit fault was only in the start function, then your instruments will still get power even if the start function was not working.

[Martin S]

It is worth knowing how to stop the engine if the stop solenoid fails. I have a Yanmar 4JH and although there is a manual override lever to stop the engine it is very hard to reach. I found this out the hard way. The stop solenoid broke and I could not stop the engine. Reaching the small lever was impossible and at the time I did not know its precise location. I later had the yanmar dealer attach about a 1 meter long thin stainless rod to the manual lever and the rod emerges at the front of the engine. If the red stop button and solenoid fails I simple push the rod and it pushes the manual stop lever. Very simple and very effective. Highly recommended.