Help! 2004 F150 Hertiage XL 6 cly. We had some very cold weather 17 deg truck sat for 2 days as lots icy roads. Started and never seemed like heater or defrost was working. Started down road and temp gauge went all hot shut down and resv had 1/2 inch coolant, restarted and temp back to normal and resv went to half went and got more coolant and added more.
Now when I start truck the temp goes to normal
upper hose never get hot open resv cap and it over flows coolant.
If I turn on heater/ def upper hose gets hot and goes fill hot temp gage.
I am thinking bad thermosat but was wondering if there is any thing else i need to buy or check before head out to parts store.
Ford lover Thanks for the help!!
2 F150s
Mustng GT

 

Thermostat is my guess. Prolly froze in the cold.

 

Had a 5.0 '97 Exploder back in the day that overheated and the reservoir was blowing its top. Thermostat was the problem. It's the cheapest and simplest fix so even if for some reason that wasn't the problem, you won't be out a lot of $$$

 

Thanks Got the T stat and will get it in the morning. Thanks

 

Ok ! Replaced T stat didnt over heat as fast and verified theold t stat was not working,
Now Upper hose is Hot lower hose cool one heater hose is cool and one hot and not heat or defrost to the cab. I am thinking water pump is next or may it be some thing else???

 

sounds like a possible air lock to me.