We purchased this truck used with 134k miles, and when we test drove it, it did not have any issues and ran pretty good. The day after we bought it we noticed that when we were going up hills it would run hot. So the 3rd day of owning it, it was in the shop. In the shop they put in a new thermostat. That didn't work so they put a new water pump in, and that didn't work, so then a new radiator. That didn't work so they upgraded to a racing thermostat per Ford, and new coolant. That still didn't work, so after almost 3 weeks of this, they agreed to take the truck back because we are just done!

I have the Ecoboost version of this F150. While driving in the Alaska Interior where temperatures often reach below zero during the winter, I noticed that my engine temperature would almost immediately climb upon reaching highway speeds of 55mph. After a few moments of overheating indication, the check engine light illuminates. If continuing to drive with that light on, the truck will begin a shuttering stall phase when I depress the accelerator.

While I understand that chill temperature at highway speeds can create havoc on the cooling system, blocking the radiator with cardboard was ineffective in this matter. I have since replaced the thermostat but that proved to be ineffective. Once again, this issue isn't occuring when the temperature is 4, 3, 2, 1 or even zero Fahrenheit. It only occurs at negative temperatures, i.e. -1, -2, etc. My mechanic, Ford mechanics and even Chevy mechanics are at a loss as to why this could be happening. Please help...