New thermostat overheating

[Cryptothedog]

I had this same issue....It's air in the system causing the temp variation. It would never burp on its own for me, even with the front driver wheel elevated. What I had to do was first replace thermostat. Then then I filled the upper hose from the thermostat hose that connects to the radiator until it registered as full in the coolant over flow tank. Then I attached the one side of the hose to the thermostat and removed it from the radiator. Then I elevated the radiator side of the hose so that it is higher than the engine (again one end is still attached to the thermostat but the other end is removed from the radiator) and filled it until it was full. Then I quickly and carefully reattached it to the radiator. Be careful when reattaching so that you don't spill too much out of the hose. Then check the level in the coolant tank and fill if necessary. Then run your truck and let it go through a heat cycle until the thermostat opens up. After that's done the level in the coolant tank may go down a bit so fill if necessary.

Hopefully that makes sense. That's the only way I could keep air out of my cooling system. If you have questions, let me know.

(I had a couple fail after a few months. I've had to replace aftermarket thermostats about every six months. Maybe I should just buy an oem one, but they are easy to change and I have a lifetime warranty on the one I bought. But when they work the temperature stays right at 207.3 and there is very little variation. The hottest I've seen mine get after finally getting all the air out is about 218 and that is towing up a hill usually.)