1960s Thermostat Test

[60eldo]

I overheated today and took the thermostat out which is 1 week old.Tested it and found these results. It a 180 stat. Opens at 210 F, closes at 190 F,,,Not sure what to think, any comments would be welcome. Did the test 3 x . Just did it one more time closed at 210 F

[Chopper1942]

Back in the day, late 50's & early 60's, we used to test thermostats when a car had overheating or not enough heat in the winter.  We used a ceramic bowl with a heating element in the bottom. You installed the cold thermostat into cold water and hung the thermostat in the water with a thermometer in the water. You plugged in the tester and watched the thermostat and thermometer for when the thermostate opened.

Your pictured setup looks good. IMPORTANT: the temperature of the thermostat is the temperature that it STARTS TO OPEN.  Your 180° thermostat should start to open within 3° of 180° ( 177°-183°). It may not be completely open until 190°-200°.

From your test results I would suspect the thermostat is defective.  I especially do not like the time that the thermostat closed at 210°.  It should not be closed until it is >180°. Just make sure you start with cold water and watch when it starts to open and then the fully open temp.

Even if this is a 210° thermostat, the engine should not overheat unless there is an issue with the cooling system. If it is puking coolant, I would check your radiator cap. For every 1# of pressure, you raise the boiling point of water 3°. Let's say your cap is rated at 7#. This raises the boiling point 21° to 233°. coolant added to water in a 50/50 mix also raises the boiling point.

At 210° the temp gauge will read higher, but the engine should not be "overheating". the vehicles today have normal operating temps from 210° to 221°.  This is for better emissions and reduces contamination of the oil (less sluge build up).