I have been having overheating issues with my 2003 f-150 supercrew. sometimes the truck runs great and has good heat, then sometimes when im driving the heat will go cold and the truck will start to overheat and throw a cylinder overheat protection mode code. I'll then pull over shut the truck off, clear the code, and everything returns to normal. I decided to buy a new thermostat. I installed it and now right off the bat it overheats. I felt the upper radiator hose and it was cold. Did the parts store sell me the wrong thermostat? or could this be something else?

 

Are you sure you didn't install the t-stat backwards? Very easy to do. And the hot to cold symptoms say that you have air in the coolant system. When the pocket of air gets to the heater core, you'll get cool air off of it.

 

Installed the same way the old one came out.

 

Did you buy a fail-safe t-stat? They only stick open.

 

You could remove the t-stat and let it run to narrow down the issue. If it still runs hot, probably your water pump. If not, could be a bad (new)t-stat. Make sure you bleed the system to get all the air out. I always install a flush kit inline with my heater hose to bleed it.

 

Running the truck without the thermostat will not harm the vehicle? Say if I have to leave it out so I can get to work and back for the day?
Also, how would I bleed the air out without having a kit like u mentioned?

 

Won't hurt it at all for a day. You can bleed it by running the engine with the cap off the reservoir and keep filling it. You can get a flush kit from a parts store for about $10. You cut a heater hose and splice in a t fitting with the supplied hose clamps. Only takes 5 minutes. I like doing this because it gives you a bleed spot that's at the top off the cooling system where air most likely collects.

 

In the process of taking out the t-stat now, and I came across something disturbing, I took off the cap of the coolant reservoir, and it reeks of exhaust. Please don't tell me this could be a head gasket.

 

Yes Sir. Very well could be.

 

could that pressurize the opposite side and prevent the t-stat from opening?