Q: My car overheated due to a burst radiator. Replaced radiator and coolant temp sensor, but still overheating. Fan does turn on.

asked by on July 07, 2017

The radiator burst at the top plastic, so I replaced it with a brand new one from AutoZone. Check engine light was on with the only code showing as P0117 - Engine Coolant Temperature Sensor Circuit Low Input. I replaced the sensor which seats into the left side of the engine block under the large coolant hose coming out of the top of the radiator. The fan comes on after the car warms up, but the car is still overheating. Not sure what to do now. I don't see any coolant leaks.

My car has 187000 miles.
My car has an automatic transmission.

You may want to check the cycling of the fan to be sure they are coming on at the correct speeds. If the fans are not coming on and maintaining the proper speeds to properly cool down the radiator and the motor, this may still cause the motor to overheat a bit. What you are describing sounds like a fan clutch that may be wearing out. A mechanical 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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