My dad took my truck on a road trip this week for bike week in daytona. i got a call and hour ago and he was asking me about the temp gauge going from aroun 190 down to about 160ish, and keeps doin this. i think it is normal , although i dont pay attention enough i have noticed this before. he is pulling a trailor, small inclosed trailor with 2 harleys in it, not very heavy load at all. anyways is this normal or not, i think yes just from my driving but i ahvent taken the truck on a trip yet, let alone pull somthin that far.

 

Yes it is normal these trucks have large capacity radiators, there is a updated thermostat from a cummins dealership that is supposed to stop it. I have not tried one yet. Goodluck,,Rick

 

As long as you don't exceed 215 you're in good shape!

 

Cummins says,

THE COOLING SYSTEM USED ON THE CUMMINS DIESEL ENGINE EQUIPPED VEHICLES PROVIDES THE CAPACITY AND PROTECTION OF THE HIGHER GVWR AND GCWR RATINGS AVAILABLE ON THESE VEHICLES. OWNERS SHOULD BE ADVISED OF THE NORMAL SLOWER WARM UP AND LOWER ENGINE OPERATING TEMPERATURES ASSOCIATED WITH DIESEL ENGINES.

THE COOLANT TEMPERATURE GAUGE WILL FLUCTUATE ON DIESEL ENGINE EQUIPPED VEHICLES. IT IS INFLUENCED BY VEHICLE LOAD, OUTSIDE AMBIENT TEMPERATURE AND EXTENDED IDLE TIME. THIS FUNCTION IS CONSIDERED NORMAL