Exhaust temperature alarm

J

johnhb67

New Member
Joined
25 Sep 2025
Messages
4
Visit site
Hi, I'm building myself another exhaust temperature alarm for less then a few dollars...
I didn't have an an alarm on my previous motor sailor and the day after I installed this, I had an air lock after clearing the intake filter and it alarmed..

my exhaust averages 35 deg C so I'm going to use a 50 deg C thermal protector switch....
cheers from New Zealand...
 

Attachments

  • temp.JPG
    temp.JPG
    76.3 KB · Views: 20
I use a cheap Chinese temperature gauge with relay from Amazon, which displays the temperature at the nav table, as well as setting off a loud alarm if the temp exceeds 50C.

The sensor is jubilee clamped to the exhaust elbow.
 
Dockhead said:
I use a cheap Chinese temperature gauge with relay from Amazon, which displays the temperature at the nav table, as well as setting off a loud alarm if the temp exceeds 50C.

The sensor is jubilee clamped to the exhaust elbow.
Click to expand...
Ditto. Nice easy modification.
 
If you use the switches in the link you need the normally open variety. These will close at the set temperature and sound an alarm. I have used a bimetallic top hat switch for years but it has never actually gone off. I do have a test switch position that will test the alarm sounder and you can test the switch with a lighter, soldering iron or a cup of boiling water.
 
johnhb67 said:
Hi, I'm building myself another exhaust temperature alarm for less then a few dollars...
I didn't have an an alarm on my previous motor sailor and the day after I installed this, I had an air lock after clearing the intake filter and it alarmed..

my exhaust averages 35 deg C so I'm going to use a 50 deg C thermal protector switch....
cheers from New Zealand...
Click to expand...
I also recommend one with a digital readout of temperature so you can monitor change over time. I fitted one of these 10 years ago linked to a separate buzzer for an audible alarm
Pardon our interruption...
 
johnhb67 said:
a bit fiddly to program, but these are cheap as chip on ali baba
Digitaler Temperaturregler, Thermostat, hochpräzises Inkubator-Relais mit zwei Chips, LED-Heizung, Kühlelektronik - AliExpress 1420
Click to expand...
or more simple would be to use this and your exisiintg alarm setup.
I used the above digital controller to monitor my temperatures before choosing what temp switch to purchase.
KSD9700 5A250V 40-120 Grad Celsius Normalerweise Geschlossen Offene Bimetallscheibe Temperaturschalter Thermostat Wärmeschutz - AliExpress 13
 
I installed one of these with the probe pushed into the edge of the pipe where the elbow meets the exhaust hose. I set it to alarm at 40C and it works well.

stat.jpg

I added a large red LED on the helm station and wired the stat into the buzzer circuit on the Yanmar B20 panel so if the exhaust overheats, I get audible and visible alarms. The way I wired it, the large red LED also comes on if the standard oil pressure or coolant temp switches activate.

This is how I wired the above, everything to the right of the dotted line is my mod.

stat_wiring.jpg

Link to stat £9 on Ebay

Other threads on the topic and the B20 panel -

D

Thread 'Yanmar control panel button problem'

Yanmar 3YM30. Control panel B20. All works fine except the starter button. Press hard, you can hear the tone in the alarm change but nothing fires. Started once by pressing very hard but can't get it to do it again. Plenty of battery. All wiring is fine. I think it's a problem with the button itself. Can these be replaced or do I need a whole new panel?

Thanks.

mainshiptom

Thread 'no cooling water coming out of exhaust'

well , no water coming out so checked impeller and looking good, checked filter and a bit dirty so clean now, still no luck.
Inserted hose into filter casing and water is running fine through engine,

so How do i clear the stopcock?
 
Last edited:
You must log in or register to reply here.

Share this page

Top