Coolant temp started going up

[Cbrooks45]

I was wondering if any one had the issue I am having now so I wanted to ask. My truck has always run at the same basic temp. Even driving across the country, my temp gauge barely moved at all. Last week when it was a cold (for TX that is 25 degrees and rainy) the temp gauge kept going up to the three quarter mark. Then going back towards the half mark. But it kept going back and forth. Again the truck has never gone above the half mark (normal operating temp). So I changed the thermostat and tested it and it is going the same thing. it is not overheating, just going up to about 240 degrees then going down to and back up again. Anyone have any idea what could cause that. I cant find any leaks and the radiator and overflow tank are full. Fan is on the pulley and always on. Its a 2012 Ram 1500 5.7.

 

[jws123]

Could possible be a bad fan clutch or water pump you also may have air in the system try to bleed it plenty of youtube vids on how to do so 240 is to hot considered overheating do not keep running it if its getting that hot you will blow head gaskets

 

[808ram1500]

Could be the radiator fan. If it's a mechanical viscous fan, you'll probably need to replace it. Cheap fix.