93 Buick Roadmaster, 5.7L, 140K miles. Car runs like a top, no leaks or noises. The temperature gauge on the dash will heat up to the normal 10 o'clock position and stop there for a couple minutes. Then it slowly climbs all the way (pegs somtimes) up over about a minute of driving. Then it immediately (3 or 4 seconds) goes back down to normal. It keeps doing this until the car is shut off. High speed, lo speed, or idling does not seem to have an effect. The car does not appear to be overheating, no boilovers, no sevice engine lights, nothing. I've driven like this for a couple thousand miles with no ill effects. Change the temp sensor in the head, radiator, fan, thermostat (even tried removing thermostat), flushed system; absolutely no effect. What's up?

The indicator device or circuit is probably defective.
check that and let us know.

I'm going nuts with the exact same problem on my 70k Roadmaster Wagon. I can see the fan kicks on, no loose fan clutch, replaced the thermostat and radiator cap and still keeps happening.

Has anyone else heard or better yet fixed this problem.

I'm really not sure its not overheating or if its the gauge wandering. No white smoke or loss of fluid, so I'm pretty sure its not a head gasket either.

I could change a handful of sensors but it looks like thats a shotgun approach.

Thanks for the help.

93 Roadmaster Estate LT1 70k original miles.

tubehead wrote:

93 Buick Roadmaster, 5.7L, 140K miles. Car runs like a top, no leaks or noises. The temperature gauge on the dash will heat up to the normal 10 o'clock position and stop there for a couple minutes. Then it slowly climbs all the way (pegs somtimes) up over about a minute of driving. Then it immediately (3 or 4 seconds) goes back down to normal. It keeps doing this until the car is shut off. High speed, lo speed, or idling does not seem to have an effect. The car does not appear to be overheating, no boilovers, no sevice engine lights, nothing. I've driven like this for a couple thousand miles with no ill effects. Change the temp sensor in the head, radiator, fan, thermostat (even tried removing thermostat), flushed system; absolutely no effect. What's up?