The patient is a 92 with 167k glorious miles. It has a new radiator that was professionally installed about a thousand miles ago or so.
While driving along at 55, I spotted the temp gauge all the way up in the hot position. Just as far as it could possibly go. The suv seemed to be running normally otherwise. When I had a chance I pulled over and popped the hood. There was no steam, no leaks and no unusual "hot" or antifreeze smell. The overflow reservoir had an inch or two of fluid in it. The radiator felt equally hot at the top and the bottom and so did the top and bottom hoses. Turning the engine back on, the belt was turning normally as were all the pulleys and the fan was spinning. I came to the conclusion that I had a gauge or sender problem. Still a long way from home, I decided to risk driving. I was soon on an interstate staying with traffic at about 75. After a while (maybe 1/2 hour) the reading came back down to normal. I did not catch it moving so I don't know if it went down in a single quick move or if it crept down.
Everything has been normal since.
What would make the gauge read high like that? It could be the gauge itself. It could be the sender. It could be a wiring fault. Is there any particular fault that has a history of creating this situation?
Charlie