Q: Overheating at stops

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I chamge my thermostat and flushes my car now when i stop oe slow down temp goes up and will go down when i take off sont know whats going on please help

My car has 136394 miles.
My car has an automatic transmission.

There are a few things that may cause this to happen. Generally, this happens when the cooling fans are not working properly due to a faulty cooling fan relay or possibly a faulty fan clutch.

The coolant fan relay helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this relay is not working properly, this can cause the fans to come on intermittently, stay on all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off.

A fan clutch works by helping to control the radiator cooling fan speeds as the engine heats up and cools down. As the motor heats up, the clutch causes the fan to spin faster to help draw more air into the radiator to cool the engine down. As the engine temperature cools down, the fan begins to disengage and spins slower. There are typically two types of fan clutches. The most common is one that is filled with fluid and uses a bi-metallic sensory system similar to that of a thermostat. The second type is an electrically controlled fan that is operated based upon various electrical inputs (i.e. engine oil temperature, coolant temperature, AC system pressures, etc.) that help to control when the fan speeds up or slows down. What you are hearing is likely the fan working harder more often than it should be. I would suggest having an expert from YourMechanic come to your location to take a look at your vehicle to determine what may be causing this.

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