EZ way to check thermostat
#1
EZ way to check thermostat
Take the thermostat out of the car and put it in a small pot or coffee can and cover with water. Heat to a boil. If it doesn't open, it is most likely bad. Hope this helps those who have questionable thermostats.
#3
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Start with a COLD engine, preferably the car sat overnight. Remove the radiator cap and make sure the radiator is full, if not top it off and wait a few minutes because it will usually need to be topped off again. With the radiator cap still OFF, start the engine and let it run a good 7 –15 minutes. The radiator will spill over a little coolant until the thermostat opens, but will then stay at a constant level of 1 – 4 inches below the opening. If the thermostat doesn’t open and is stuck closed, the coolant will spill up out of the radiator sort of like Old Faithfull at regular intervals. And, if you shut down the engine and the coolant continues to spill up out of the radiator, then you have a closed stat in a hot engine.I did one just like this last week.
Be careful working around a running engine, especially with the cap off and coolant spilling out.
Be careful working around a running engine, especially with the cap off and coolant spilling out.
#4
or you could just watch the scan tool--if coolant temp goes over 195 and it's not circulating through the radiator yet---a good bet that the thermostat is stuck closed. if the radiator is circulating well below 195---a good bet the thermostat is stuck open or physically broken.