Temperature Gauge Testing?

[eriefeelin]

On my 1990 260 MerCruiser I have replaced the temp. sending unit on the thermostat housing and my IR gun reads from 135-145 degrees when measuring right on the brass base of the temp. sending unit. The gauge on the dash reads close to 170 degrees. Is there any way to test these dash gauges for accuracy?

 

[Don S]

Re: Temperature Gauge Testing?

When you get your temp gun up to 140?, have the gauge wire disconnected and witn an ohm meter check the sending unit. You should show 121-147 ohms if the sender is correct. There isn't any methods of testing the gauge itself. Corroded wiring would cause the gauge to read lower, as higher resistance (ohms) would cause a lower reading. 212? = 36-41 ohms.

 

[eriefeelin]

Re: Temperature Gauge Testing?

Thanks Don when using my ohm meter how would I go about testing the sender as far as which red or black probe goes where when testing the sender?

 

[abj87]

Re: Temperature Gauge Testing?

Thanks Don when using my ohm meter how would I go about testing the sender as far as which red or black probe goes where when testing the sender?

doesn't matter

 

[Boatin Bob]

Re: Temperature Gauge Testing?

It's just a resistance check so polarity doesn't matter, just put one probe at the base of the sender or a good clean surface of the block for the ground and the other probe goes to where the wire attaches to the sender. Make sure you select a fairly low range on the ohm meter.