Hey all got a 2008 dodge mega cab 6.7l, been having this issue for a long time. Dodge cant ever seem to figure it out(but havent tryed there hardest).
Coolant fills my over flow right full and on the ground only when the motor is cold and thermostat is still closed and I drive it before thermostat is open. Dodge had the truck for 3 weeks and could not get it to over flow on them, so they changed thermostat and a rad cap.

Recently i bled off the coolant system to make sure no air in it.
Been having to run the motor upwards of 1 full hour before driving to keep over flow from filling. once motor is warm and thermostat is Open i have no issues even when towing heavy loads.

Also recently took the truck to a differnt mechanic and he tryed cleaning EGR system and unplugging it. seemed to not help.
Hope its not a HG but dodge refuses to belive it is to after pressure testing and checking coolant system for hydrocarbons.

Any ways hope some one can help
Thanks


Oh ya if i drive it before t-s opens it starts blowing cold air from heater and engine temp maxs out at 120C, then soon as t-s opens warm air blows again and temps go to norm