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Q: Overheating going over 65mph on interstate.

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My truck wants to overheat on interstate when reach speeds of 65 mph or more. I have replaced the radiator, Fan clutch, thermostat, and water pump, all within the last year. What else could it be? Does radiator need flushed?

My car has 127000 miles.
My car has an automatic transmission.

It sounds like you may possibly have a clogged radiator or potentially cooling fans that may not be coming on at the correct times. I would suggest having the radiator flushed and checking the cooling fan relay to be sure it is properly triggering the cooling fans to come on at the right times. The other possibility may be that the fans may be coming on, but not at the right speeds which may be impacted by the cooling fan resistor, so you will want to check this as well.

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