I have a 1996 GMC Suburban. The temperature gauge seems to be malfunctioning. After only about 5 minutes of driving the temp gauge will shoot up and then shoot back down. It will shoot up to the red zone, stay there for a minute or so and then rocket back down to below normal. Even though the gauge shoots into the red zone, the truck never over heats. Never hear any hissing, never see steam and seems to perform just fine. We used to pull over when it got to the red zone but now we just drive through it because it always comes back down without incident.
It sounds like you may have a faulty gauge or there is a problem with the sensor that is sending the signal to it.
Either way you should have it checked out. You don't want to get so used to not believing it that if there is something wrong it gets ignored and the engine over heats.
Have a technician test the system so that you can have some piece of mind.
〉 Answered on Sep 8th, 2008 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines