Over the last 2 winters I have had consistent issues with my Ford F 150 whenever it gets under 40 degrees. The truck will get hot very quick and into the red and I will have to pull over and shut it off. I notice when I pop the hood to look around that sometimes there are bubbles inside my overflow tank and other times there is anti-freeze all over the hoses and even on the underside of the hood. I have had it into a mechanic and they were perplexed cause they could not get it to overheat and they thought it was the overflow tank. I disagreed but gave it a try but yet 2 years later it still does it. During the Spring and summer it seems to run fine. Just looking for possibilities into where my problem could be or is it time to move on?

Thank You

 

Try replacing the thermostat.

 

What he said.
What year? What motor?

 

Any chance it's straight water and under 40 is under 32?

 

I agree that the symptoms do make one wonder if there's just water in there. However, the OP did say that he took the truck to a mechanic. If that guy didn't test the strength of the anti-freeze, I think it's time for a new mechanic.

 

Test the coolant for exhaust gases in order to rule out a bad head gasket.

 

OP says it only happens under 40 degrees. I would think a bad head gasket would be all the time.

 

Wouldn't cost that much to rule it out, though. Anything that would make it run hot under 40* should make it run hot at 90* you would think.

 

How do you test for that?

 

Anytime you see bubbles in coolant....not a good sign