Testing water temp gauge?

[Speedwagon]

So, I replaced the water temp gauge in my boat last year, because the original wasn't working. Had the boat in the water today, to run some tests on it(needs a bit of work), and the engine ran for about 10 minutes or more. The water temp gauge didn't move though. And it doesn't flicker like the rest of the gauges, when I turn the ignition on.<br /><br />So any suggestions on testing this 8 month old gauge?

 

[Silvertip]

Re: Testing water temp gauge?

You replaced the gauge but did you make sure the sender was OK first? The gauge can't work correctly if it doesn't get a signal from the engine.

 

[Speedwagon]

Re: Testing water temp gauge?

Well, IIRC, it was working at the end of last year, when I put it in. Though I did not replace the sender, if memory serves, because noone had it in stock.<br /><br />But I would expect the gauge to flicker like the rest of the gauges when I power on the dash.

 

[Silvertip]

Re: Testing water temp gauge?

Look at it this way - at high temperature the sender has very little resistance (its a variable resistor) so the gauge reads high. At cold temperatures the sender can have very high resistance (240 - 3000 ohms) depending on type so the gauge needle will not even flicker. Therefore, if the send wire is open or the sender is note functional, the gauge senses high resistance and reads cold. Measure the sender resistance. If it reads about 30 - 40 ohms hot (put it in hot water) and 240 ohms or higher at 50 - 60 degrees its working. If not, it's bad.