Overheating Problem
 

I was driving last week and saw that the over temp light was lit and the gauge pinned. Fortunately, I was a couple of blocks from home.

The engine was smokin' hot, but there were no leaks I could see. The cooling reservoir was low initially, but then after the motor started to cool, the level dropped down to nothing.

Bad thermostat? Any other obvious signs for which I should be looking?

Thanks,
Vin

Thermostat is certainly a #1 suspect. Do the electric cooling fans come on? They are controlled by a thermo switch on the radiator just below the main inlet hose. If they don't come on, it will overheat in traffic/slow driving.

Also, some cooling leaks only leak when the engine is hot. Could be losing coolant to one of those. Could be a clogged radiator or a weak water pump. Worst case scenario would be a bad head gasket.

The fans seem to be running if I turn on the A/C., but does that force them to run? I added about 1/2 gal. of fluid to the tank to bring it up to the minimum.

I will start it again today and take a look for any leaks and at the fan. I will probably change the thermostat tomorrow in any case.

Turning on the A/C will force the fans to run.

Don't forget to bleed the cooling system of air. Excessive air will also cause the fan thermoswitch to not always activate when it's supposed to.
http://www.clarks-garage.com/shop-manual/cool-02.htm

http://www.clarks-garage.com/shop-manual/cool-08.htm

I ran the car for 10 minutes yesterday, the temp gauge went up steadily, but the fan did not go on. After I turned it off, the radiator was still cool to the touch. I will replace the thermostat and see if that helps.

Thanks for the help,
Vin