I'm having a cooling issue and not sure what else it will be. On Sunday I was outside of Pittsburgh and was driving my truck first thing in the morning, i had driven it about 4-5 miles then the heater started blowing cold air, not hot. about 3 minutes or so later the temp gauge started going all the way up. I pulled over in a parking lot and let the truck sit for a couple hours while i waited for the parts store to open so I could replace the thermostat.

Next day, i drive back home to VA, truck worked perfectly. Tuesday morning, i start to drive to work, get about 5 miles and same things happens, cold air blowing, not heat. Then the temp gauge starts going all the way up. So i parked for a few minutes then all is fine, i made my way home and replace the water pump.

NOw wednesday morning, on the way to work and same thing happens in the same area - about 5 miles down the road.

What's left to check???

2003 F150 SuperCrew
V8 4.6 4WD

 

What about your radiator fan? If it's not spinning maybe the fan clutch is at fault?? Just something to check and cross off the list.

 

another bad thermostat---water pump
try a ford thermostat

 

Hopefully not a head gasket........

 

That is a strange one. If the thermostat was stuck closed or the fan behind the radiator was faulty the heater should put out lots of heat, assuming the coolant level is good. It sounds like the coolant is not circulating for whatever reason.

 

The new thermostat was one that when it fails it should stay in the open position. Coolant level is good.

 

ya I missed the heater blowing cold air comment. Lol

 

Airlock?

 

It could be a low coolant fill that has a air bubble moving around but it sounds alot like a head gasket to me. Is the degas bottle and upper radiator hose getting pressurized? If so then combustion pressure/gases from a bad head gasket is being forced into your coolant system via the bad gasket seal. These hot combustion gases move around in the system and when they come to the ECT senser they spike the gauge. It will also prevent hot coolant from entering the heater core and you will blow cold air until the bubble moves again. Have a hydrocarbon test performed on the coolant if hydrocarbons are present in the coolant then a blown head gasket is the problem. Good luck.

 

Just an FYI.... Actually now having a new Remanufactured engine put in. The #6 cylinder was where the head gasket was leaking which was causing the above problems.

Paying $3900 for the new engine. 3 year or 100k mile warranty.

 

Thanks for the update. Good luck.