My 1999 Suburban has been running hot at times. While driving, everything is normal. When I stop, temperature goes beyond 210, but not in the red zone. As soon as I take off, goes back to normal. Also when it is hot, opening the hood decreases temperature. Thermostat was changed, same problem. Any ideas?

Thanks

What about your thermaticly controled fan?If the hub is not engaging the fan to draw more air through the rad when the engine is warm, you will get symtoms that you described.
chuck's

Thanks Chuck's. But I thought the fan was mechanical, with a clutch. Could it be the clutch? Thanks

Yes the fan has a fluid coupling clutch. If the fluid leaks out the clutch becomes inoperative and the fan will freewheel (slip excessively). When your moving down the road at freeway speed the need for a fan is moot. however at slow speeds (<30mph) the fan is needed to move more air. If the air is not moved at a speed consistent with maintaining steady temps, temperature fluctuations not unlike yours occur.

Best bet is to change your fan clutch. It's a hell of a lot cheaper than the alternative (blown head gaskets, cracked parts, etc....)

Larry

Thanks Larry,

Did that, plus drained and flushed the radiator, same problem. My next step is to change the temperature sensor. I doubt its the head or gasket, I have put over 1500 miles on it since the problem started, no problem.

Thanks for your help.

John