1998 8.3 diesel water temp

I have a 1998 Monaco with the same engine that did the same thing on the way to Baltimore. I pulled over and checked the water and could also see that it was not overheated I drove on checking it a couple of more times. Short solution was that either the sending unit or the gauge had failed. Replaced the sending unit and no change. My solution was to have the shop get a new gauge, sending unit, and run new wiring from the front to the back. Never another problem and even towing a heavy car trailer over Fancy Gap it never passed 190 degrees. Normally without the trailer it stays around 170. Hope this helps.