Exhaust temp alarm

[Sailfree]

The overheating alarm on my Yanmar 4jh3-TE is integral with the control panel and not very loud and can be missed when using high revs.

The back of the panel is inaccessible and the panel screws are turning with their inaccessible nuts.

Rather than risk drilling out the bolts and finding ways of repairing them I was thinking of fitting an additional alarm.

I assume this could be either taken in parallel from the accessible engine temp sensor or a separate exhaust temp alarm.

Any experience of this problem or advice please.

 

[dom]

Goodness me; I recognised the problem of the inadequately loud alarm a couple of years back, decided to fit an exhaust temperature alarm - and here's the bit I'm not so proud of - never got around to it. Definitely will now!

PS: my panel is accessible at the back via the stern locker if you want to take a look or want some photos.

 

[nimbusgb]

If you are going to the trouble then fit a stand alone system with its own sensor. No point in relying on one sensor.

One of the ones with a sensor attached to the exhaust pipe itself will do the job.

 

[VicS]

The overheating alarm on my Yanmar 4jh3-TE is integral with the control panel and not very loud and can be missed when using high revs.

The back of the panel is inaccessible and the panel screws are turning with their inaccessible nuts.

Rather than risk drilling out the bolts and finding ways of repairing them I was thinking of fitting an additional alarm.

I assume this could be either taken in parallel from the accessible engine temp sensor or a separate exhaust temp alarm.

Any experience of this problem or advice please.

I see no reason why you should not do either, or both. They serve slightly different functions therefore fitting an exhaust temp sensor in addition to the engine overheat warning is in itself an attractive idea

The wiring diagram in the manual at http://www.motoren.ath.cx/Download.php?filename=/yanmar/4JH3.pdf may be useful. Don't confuse the switch for the warning light and buzzer with the sensor for the temperature gauge if you have one

Note that the warning light switch is an earthing switch so an additional buzzer will need a power supply. If the ignition switch is inaccessible this will have to be provided from elsewhere via a fuse.

With clever use of diodes it should be possible to fit an additional buzzer that will serve both as exhaust temp warning and back up to the existing engine overheat warning.

 

[Jokani]

I fitted one these NASA exhaust alarms last year:

It warns you before the engine starts to overheat.

East to fit, whole job would be less than half an hour, longest part was deciding where to locate the display. It is not waterproof, so just inside the hatch was best for me.

 

[VicS]

I fitted one these NASA exhaust alarms last year:

It warns you before the engine starts to overheat.

It warns you of an overall loss, or serious drop, in water flow but it wont warn you of engine overheating due to restricted flow through the engine itself, faulty thermostat, etc.

It is therefore a useful additional piece of instrumentation but is not a substitute for the existing engine instrumentation.

 

[tudorsailor]

The overheating alarm on my Yanmar 4jh3-TE is integral with the control panel and not very loud and can be missed when using high revs.

The back of the panel is inaccessible and the panel screws are turning with their inaccessible nuts.

I assume this could be either taken in parallel from the accessible engine temp sensor or a separate exhaust temp alarm.

Any experience of this problem or advice please.

I had a Vetus exhaust temperature sensor fitted last year to the Yanmar exhaust. This week, while motoring I wondered what the irritating beep/whine was. It was the alarm! Not very loud and easily ignored. I have a raw water intake strainer with a see-though top and as far as I could see, water was flowing, but there was some sea weed in the strainer. Temp gauge showed a normal temperature. I stopped the engine and started sailing. While under sail, I cleaned the raw water intake strainer which was a bit green with grunge. When I next used the engine there was no beep. I tested the sensor by jumping across with a multimeter and reproduced the pathetic beep/whine so I was not imagining it.
I wonder if the sensor works so that the higher the temperature the louder the alarm which seems unlikely.
So having gone to the trouble of getting the sensor and alarm fitted I now wonder how to make the alarm louder.
TS