Originally Posted by RI 06RAM
to be honest im not sure how fast the gauge went up but the truck wasn't boiling over just the gauge went up i was driving an when i stopped i looked down an it binged an said check gauges an it was almost in the red so i pulled over an the elec fan wasn't on i looked at the over flow bottle an it had coolant in it so i started driving an it went rite back down to normal an never went back up i just dnt know why the elec fan never came on ? hope that answers ur question
Some times a loose ground cable on the battery, or the other end being loose or rusty can cause gauges to go up and down for seemingly no reason. I added an extra ground cable from the battery to any metal bolt under the hood. That stopped all my ghostly encounters. If the truck was truely hot, then the gauge would not have gone back down. So I suspect you have these ground gremlins like I did. It is a real cheap try. Apiece of #6 copper wire with a lug on each end and it does not need to be insulated either.