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Q: Overheating

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Vehicle was overheating, noticed leak in radiator. I replaced radiator, thermostat, and the fuel filter since I was already working on the truck. The truck is still running at around 210-240 while driving, and climbs to 260 when stopped at red-light. What else could cause my truck to reach that temp?

My car has 180000 miles.
My car has an automatic transmission.

Hi There, I would recommend also checking the cooling fans to be sure they are coming on. A common problem associated with cooling fans is the relay that fails resulting in them not coming on to help cool the radiator at the correct times. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, 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. The typical electric cooling fan circuit includes a temperature sensor, a relay, a control module and the fan motor. The relay is the component that fails most often, so be sure to test the relay as well as its power supply and ground connections. A good relay coil will typically read 40 to 80 ohms. If resistance is high, the coil may still be working but it is failing, or it may not work when electrical loads are high. If the coil has no resistance, it is open and has failed and you will need to replace the relay.

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