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Q: My car keeps running hot then it cools down

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My temperature gauge on my car will run cold, then hot, then cold again.

My car has 181523 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. There are two po...

Hi, thanks for writing in. There are two possibilities here: either the physical temperature of the engine is indeed fluctuating significantly, or the sensor and/or circuit that feeds the temperature gauge is malfunctioning. The sensor (and circuit) can be tested and, if necessary, a temperature data logger can be deployed to measure the engine temperature over time to see if the temperature is in fact fluctuating. If it is there could be an issue with the cooling system thermostat, water pump drive belt, radiator blockage and/or a malfunctioning cooling fan. YourMechanic would be pleased to evaluate the issue for you and identify the cause of the problem, that is whether it is electrical or something else.

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