Hello All, any help here is greatly appreciated. 2012 - F250 - 6.7 - 105,000 k. Last week heat was intermittently working, 2 days later no heat and temp gauge maxing out. Changed thermostat, checked fan, drained, flushed, and replaced coolant, also there has been no noise warning of water pump, I know that doesn't rule it out. Weird overheating since no overheating at idle and temp will drop back down while driving if I don't accelerate. Reading I have seen water pump - heater coil - etc. etc.. Just trying to get some feedback prior to shelling out $$$ to diagnosis.
Thanks in advance!

 

When the engine is up to temperature, are the radiator hoses stiff or squishy? A squishy hose could be indicative of a poorly performing water pump.

 

Sounds like you may have a stubborn air pocket in there. Heat then no heat, & temp gauge moving up & down. That could do it. Did you bleed the system when filling it back up?

 

Get a guage to measure the coolant tank

Take a measurement at idle

Take a measurement at 2000 rpm

If the tank pressure is the same, you may have a water pump problem

If the pressure at 2000 rpm is over 20lb psi, possible cooling system containment problem*. Early 6.7,s had a pax side head problem due to cracks in the pax side head*. This was fixedin the Gen 2 engine released 2015

 

Wow man you went full; monty on that sucker.
First how do you know the truck was over heating? The computer will put you in limp mode if it gets too hot.
Next you may have a heater problem. Maybe a blend door is not working. Did you have heat in the defrosters? If your blend door is stuck it may be in the defrosters. Usually a heater will stop blowing heat for 2 reasons. the first is stated above nesx one is no water in the truck. If the truck doesn't have water first sign is no heat because there is no water in the heater coil. There may be a valve in the heater hoses that turns on the water while running the heater but I don't think that is the case anymore because you can set the temp to 60 to 80 in the truck. I have seen vacuum modules go bad before.
I would not think you needed a water pump thermostat or a coolant change. With all the money you spent so far the dealer would have fixed your truck by now. Not to rip you but you should have come here first. Lots of people here to help you.