Hello,
My '97 Riviera is all of the sudden overheating, all the way into the red. I pulled over and noticed that the radiator was cold. I get hot air coming out of the heater, so I think that rules out a bad water pump, as coolant appears to be circulating that far. Could the thermostat be stuck closed?
Thanks.
Mikel

Update: Got a new thermostat and it made no difference. I did read the threads about purging the thermostat and I made sure all air was out of the bleed screw. The upper hose gets a little hot but the radiator remains cold. The lower hose gets a little hot, but I think it's residual heat from the engine coming from that side, not from the radiator.

I started the engine with the thermostat housing off and no thermostat, to see if the water pump was working. Coolant began coming out at a leisurely pace (I was expecting more of a quick stream). I put the housing back on (no thermostat) and it did exactly the same thing. No significant flow and the radiator remained cold.

I suppose I'm looking at a water pump at this point...? Thanks.

PS. There is something that really puzzles me - The temp gauge will go ALL the way into the red (260F) but there is very little pressure in the radiator hoses. The engine doesn't feel abnormally hot either. You would think that at that temperature the coolant would start boiling and the hoses would be rock hard. I am not seeing any obvious overflow from the radiator.

maybe you need to new temp sensor

De Tension the accessory belt, grab the water pump pulley, and see if you can wobble it. Spin it also and see if there is any resistance. I would also scan the car and monitor the coolant temperature to see if it agrees with the gauge.

It was the $17 temp sensor... The car sat for 3hrs and it still showed 200F! Thank you all.

hey im looking for a coolant temperature sensor and i cant find it ..does anybody have a link to where i can purchase one?