Testing my temp gauge

[guy48065]

My temperature gauge hardly moves--if at all. Before I put this up for the winter I'd like to test the sensor & gauge.
Can I just remove the sensor and put it in hot water? I'm guessing there will be water behind that sensor (open system). Just let it run into the bilge?

 

[Scott Danforth]

first, check the ends of the wire at teh gauge and sender (tan wire)
check the ground at the gauge

most likely its corrosion on the terminals

then check resistance of the sender. should be a 230-30 ohm sender (most in the US are)

 

[Grub54891]

You can test it in a pot of hot water without running the motor. Be sure to hook up a go ground and keep the connector on the top.

 

[guy48065]

You can test it in a pot of hot water without running the motor. Be sure to hook up a go ground and keep the connector on the top.

Engine off, key on...annoying alarm ON.

 

[Grub54891]

I

Engine off, key on...annoying alarm ON.

get that, but it will show you if the gauge is reading. I often get annoyed at squaking people but do my best to ignore them.
or just put a temporary pipe plug in the motor if you are running it.

 

[Horigan]

The alarm is likely driven by a separate oil pressure switch, not the sensor that feeds the gauge.

 

[guy48065]

The alarm is likely driven by a separate oil pressure switch, not the sensor that feeds the gauge.

Yeah it's normal but loud, continuous, and real annoying.
My other boat just beeps once as a self-check, then silence.

 

[guy48065]

I thought the 'standard' sensor output varied from about 240 to 40 ohms?
I bought a 200 ohm rheostat to test the gauge and wiring. At first when I jumpered the pot in place of the sensor the gauge didn't budge off the pin. I unplugged the gauge and checked the voltage on the 3 wires with a dmm. Seemed ok but I'm not sure what it 'should be'. Plugged the gauge back in and restarted the motor. Now it moved up to 100*. Subbed the pot back in place of the sensor and now can get the gauge to sweep. It would seem the problem was at least partly dirty connection to gauge.

Sensor measures about 450 ohms when motor is warmed up. Sensor terminal is bright brass and sensor body has continuity to ground. Shouldn't this be reading ~150 ohms on a warm motor?