04, 2500 was running a little on the hot side, so I decided to flush & replace the coolent. Did the 50/50 Prestone mix and I put in a O'Rillies off the shelf thermostat. Now it's running even hotter!! It gets up to 212-215 before the thermostat opens & it levels out at 203-205 degrees.
O/S temp was 88 degress, I was traveling 75 mph pulling a 1500lb trailer with a ATV on it, no biggy. EGT temp was anywhere between 832 to 880; ENG temp steadied out between 203 & 205, but went as high as 212-217 when I got on it to pass. My LOAD percent was between 37% to 44% and my boost was between 15 to 18.
What is a normal operating temp anyways, am I far off and worrying about nothing or am I screwing up? Any suggestions or ideas to get the temp down would be greatly appreciated.

 

You have the wrong coolant in your engine. You need HOAT coolant. Zerex has G-05 coolant that meets the Chrysler HOAT specification. I have heard that you can have problems with your water pump and/or radiator/heater core using the wrong coolant.

The factory thermostat is a 190 degree thermostat. There is also an option for a 180 degree thermostat, but that is an option, not the one that came from the factory. You may want to check if the thermostat is opening at the correct temperature.

Last, you may want to check your codes to see if you have the P0483 code. If you have this code it means that your fan clutch is failing.

I just went through the same problem that you are having. I replaced the fan clutch due to the P0483 code and that was the problem.

I hope this helps.

 

Only use a Cummins thermostat. The rest don't work right.

 

Boost seems a little low you might have a bigger issue than the thermostat or coolant. My 06' did the same thing ran warm and really jumped up when I got on it especially pulling my G/N right before my turbo blew. Another issue might be a burnt ring causing friction. Are you burning oil?