Just had the motor and transmission replaced with GM reman as well as the water pump,radiator, fan clutch, temp sender and T stat and this engine is running hot at idle. It will cool down if you increase the rpms but left at idle it will creep up to 225 degrees. I plugged in my scan gauge to confirm it wasn’t a faulty gauge and the temp is normal while driving but once you stop it climbs up to 225. Like I stated everything is new this is driving absolutely nuts!!! Mechanic that did the work said it could be air in the system but I’ve drained and refilled the coolant twice and nothing changes. Drove the truck 325,000 miles before replacing the motor and it never ran hot really don’t want to harm this new motor by overheating any clues as to where to go next?

 

Is the radiator shroud properly installed?