Wondering if anyone can help identify the cause of my overheating problem on my F-150, which occurs whenever I tow during warm weather. I have towed trailers for many years without any problems whatsover and know it heats up after 15-20 miles of towing. I have changed the water pump, the temp sending unit, the thermostat and flushed the radiator 2 times to no avail.

This problem only occurs at higher speeds and it cools down almost instantly when I decelerate or idle the engine.

 

Welcome to the forum
I would suspect a bottom radiator hose may be sucking shut at higher rpm restricting water flow. You may try a new set of hoses. If that's not it, you could have a partially clogged radiator that flushing won't cure. Maybe have a local radiator shop look at it out of the truck. Or, your fan clutch may not be engaging at high temps at high speeds.

 

I had that problem of overheating at freeway speeds and higher then cool down and be fine around town. It was the water pump. The mechanic showed me the old one, the impeller vanes were corroded and half gone. At higher rpm the pump wasn't pumping enough water.

Oops, I missed the part about you putting in a new pump, duuhhh

 

Thanks for the suggestions, I have not changed the bottom radiator hose and it is quite soft. One person suggested that the catalytic converter could be plugged and it may contribute to an over heat problem. Has anyone ever heard of this?

I am very frustrated with this problem as I have spent a lot of money and no solution to the problem.