I have an 05 5.9 that runs around 200 normal and light trailers and 210 with heavy loads and 40ft camper. just recently it gets 215 randomly driving no trailers and even hotter when going uphill. coolant is slowing disappearing somewhere (not in oil) just changed oil today and filled coolant levels up. need a new fan clutch soon but that can not be the reason it spikes temp when driving 70mph. at idle it doesn't get even warm it stays at normal 190. had a few say may have an air pocket in the line or headgasket on the valve side (hints no water in oil) or water pump. anyone have any related problems or tricks or tips or ideas what it could be? or any good mechanics in the east texas area?

 

Check for bubbles in the coolant fill when full and idling if there are some head gasket! Coolant is burning off I assume. also a bad fan will cause it to get hot even at 70. Turn on your A/C fan should turn on.

 

Thanks so the a/c can cook down the motor?The fan is turning but I can slow it down to a stop with a piece of cardboard (heard that's how to test the fan clutch) was hoping I could wait till after winter for one haha. I'll look at the coolant for bubbles. Thanks again