There is a bleeder valve on the top of the engine and sometimes one on top of the radiator. Bring the truck to operating temperature and then open the valve until you get a solid stream of anti-freeze. I usually repeat this procedure to clear the air out of the cooling system. If that is a problem it should help the truck run cooler. My trucks will run at 185-210 normally with the AC on. If going up a grade or towing a trailer it can climb to 235 pretty quick. I drive by the engine temp, not speed or RPMs. Sometimes I will have to slow down some to stay in the comfortable temp range. An AMG field rep told me that you can run the trucks at 235 and not hurt a thing. I still won't do it.

 

Thanks 3hummers by the sound of it, yours run about the same as mine... With AC on around town 200-215, on freeway 210-225 and towing on freeway 210-225 with jumps to 235-245 which had me worried. Like you I will back off the gas when that climbs and I guess NEVER drive with piece of mind... My experience in 2 years are these are not a truck you can rely on. Between my PMD, fuel lift pump, and now cooling system, I have been stranded just city driving too many times! how would anyone trust it off road?!?!

Towing my boat I hit 245 and my heater control valve plastic cracked, one hose broke off and all my coolant pumped out! WTF is this made of plastic for?!?!