Temperature gauge issues

[AZ4x4]

I have a reconditioned 302 with a whole new cooling system, but my temp gauge leaves me wondering. Is there a way I can test the thermostat and the gauge to make sure they are talking and I am within a safe temperature range? This is one of my biggest fears when it comes to vehicles and I really don't want to worry about it all the time. Any help would be greatly appreciated. Thank you.

 

[Lawndart]

Place thermostat in water as it warms to boil. Observe when it opens.
Use an IR thermometer and point to intake near sensor when taking data point.

 

[broncnaz]

The tstat and guage dont talk. Whats worring you about the electric one?
Get a mechanical guage and hook it up in place of the electric one that should show you what the temp is mechanically and you can kinda verfiy if the electric is on or off. Or get a infared temp gun check temp near teh t stat to check against the electric one.

testing in a pan of water will only tell you that its opening even then you cant just throw it in a pan of water it needs to kinda hang in there as the bottom of the pan will transfer heat to the tstat and it may be hotter than the water temp. But still that only tells you its opening at some point when its in a engine there things are different. The tstat is not always fully open.
Whats your current temps? Newly rebuilt engines tend to run hotter than normal for awhile.

 

[smokinjoe]

As others have said the t-stat has nothing to do with the gauge reading other than actually adjusting the temp of the engine. The gauge sending unit sends the signal to the gauge. The t-stat opens and closes either restricting or allowing coolant to cycle through your motor.

T-stat is set at a specific temp. Colder than that temp and the t-stat stays closed (allowing the engine to warm up), hit that temp and the t-stat opens allowing coolant to circulate through the motor.

The gauge send unit is a thermistor that reduces volts based off temp, the different volts being sent by the sending unit is what determines where the gauge needle hits on the gauge.

Or run a mech temp gauge like many have said which is an enclosed mercury (I think) setup . . .basically a thermometer in your car.

 

[AZ4x4]

I'm sorry. I didn't mean the thermostat, I meant the temp sending unit on top of the engine which talks to the temp gauge. I'm wondering how to verify they are talking and the right temp is being transmitted. Thank you.

 

[70_Steve]

I'm sorry. I didn't mean the thermostat, I meant the temp sending unit on top of the engine which talks to the temp gauge. I'm wondering how to verify they are talking and the right temp is being transmitted. Thank you.

The boiling water thing will work, but a pain to set up. The temperature sender is a variable resistor with the wire as the voltage/current source, and the sender grounded to the block, by means of the pipe thread mounting, to complete the circuit.

Set up a hot plate with a pan of water near the engine compartment.
Remove the sending unit.
Connect a wire from the engine (good ground!) to the sending unit. Attach with a hose clamp?
Stick sending unit with wires into pot of water.
Heat the water to boiling. This should be 212° give or take...
Look at gauge. What's it say?