Towing Heat

[lord-dogbert]

With 21k stock miles we just finished towing the 5th wheel on a very familiar route down i395 from Yosemite to Rancho Cucamonga. The last two trips were with my 8.1l 2500hd with an Allison transmission and the trailer weights are always generally the same, +/- 200 pounds. Truck is an 07.5 LMM 3500HD dually with the 6 speed Allison. Outside temps were normal 105 degrees.

 

The problem is related to tempertures up grades, my old truck never exceeded 210 degress coolant temp, this truck runs from 210~245 regularly and 2 times exceeded 245 so I pulled over for a few moments in a turnout for it to cool down. I was running the air as usual and crusing around 50~55. I have the stock chevy grill on the front so the radiators are fully exposed to the airflow.

 

This is my first long range towing trip in the heat. Is this normal for LMM diesels?