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MGB Testing temp sending unit 1979 MGB

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Ray7Smith

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A friend of mine recently purchased an MGB. The temp gauge does not register any temp change. How can I test the gauge to ascertain if the problem is in the gauge itself, or the sending unit in the head? Is there a way to test the sending unit?

The two radiator fans are also not working. What is the procedure for testing the sensor located in the radiator header tank? Can the fans be wired directly to a switch? If so how can this be accomplished?

Thanks for your input.

Ray
 
You can test temperature senders or switches on the car by placing the sensor in a ceramic coffee cup and inserting an in cup heater and bringing to a boil then checking the gauge to verify the reading. You can use a candy thermometer to check intermediate temps to check fan switches for accuracy as well.
 

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Assuming it has the original type fan switch, you can check the fans by unplugging the thermostat wires on the radiator and hooking them together. If the fans work, the switch is bad. Do what Bill says on the sender to check it out. One or both could be bad. Unusual, but wouldn't be the first time. Make sure all connections are good also.
 
Yes.

Mine.

The reason I asked if the fuel gauge worked is that when both the temp gauge & fuel gauge fail, or wander intermittently in tandem, then the gauge Voltage Stabilizer up under the dash (Moss 131-555)has failed.

Colin
 
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