My 06 Hemi 4x4 has recently been acting up. The truck warms up fine usually, although occasionally i havent had heat until it is all the way in between the middle and hot side of the gauge. The temperature has been fluctuating from exactly in the middle, to the black bar right before hot, and hasn't overheated or went past that line, and no check engine lights. I am thinking it has air in the system, and when i checked the radiator and expansion tank, the tank was very low but radiator full. I also replaced the radiator cap. To me it sounds like one of three things, air, thermostat, or the fan clutch possibly. Any advice would be appreciated, thanks.

 

Sticking thermostat?

 

Interesting. I am having similar but different problem recently. But let's talk about you first.

You are not getting consistent heat to the cabin, yet the temperature is running on the higher end of the dash gauge. To me this points directly at the thermostat and only the thermostat. The clutch fan is ruled out because if it is running as hot as you indicate, and the thermostat is working properly, then you would definitely have plenty of heat in the cabin regardless of the fan. The fact that you have little heat when the temperatures are actually on the high end, this indicates the thermostat is the problem. A check on the fan is simply your ear and your hair ... can you hear the fan justa givin'er when the engine is running up at those temperatures? It should be quite noticeable. If you raise the hood and stand by the drivers door fender, it should also be blowing your hair back - catwalk end turn style.

My temperature is a little different but also the same. Working but a bit wonky on the other side of half gauge. Despite the weather here being quite cold, my engine is not holding temperature as it used to and as it should. When it comes up to temperature and the thermostat first opens, it goes a bit high past the middle then drops down to the first black line on the left. Then it continuously cycles from there to mid point. I am going to replace my thermostat. It is working, just not to my liking. It is original, old and perhaps sticky. It should be holding much more steady once up to temperature and driving around. It just is not as responsive and doesn't hold temperature as well as it used to. Everything else is just fine. I will put in a new oem 203deg stat or maybe try the Stant SuperStat @ 203deg for 30$ and see what happens.

Whatever you do, if you replace your thermostat, please do not put in a 180. Put in the design temperature stat, 203. You do not need a colder thermostat. You need a properly functioning one.

 

Well there you have it. Found the problem with my thermostat. The bottom piece, the bypass pressure plate, had separated from the main body. The thermostat is fine and works perfectly otherwise.
A brand new Stant thermostat is now stove-top tested for function and opening temperature. Ready to put in the new one.
The old one, I will JB weld the bottom back on and keep it as a spare.
Btw: the new Stant is exactly the same in every way as the old oem thermostat. Right down to all the stamp markings on each of the components. Ie: the oem is probably supplied to Dodge by Stant.

My temperature gauge now rises to just under half and stays there, rock solid.

Hope you get yours fixed too.