Cooling System Diagnosis

[sjarrett71]

Here's my problem. I cleaned my radiator and engine cooling system, replaced all the hoses, 190 degree thermostat (times 2), temp gauge sensor, and eventually installed a new aftermarket temp gauge. With both the old gauge and the new, it would get up to about 240 degrees before the thermostat would open. Then go to about 190-200 and start to heat back up. While it's doing this, I can go out and grab the heater hoses and radiator hoses and they are scalding hot but the radiator is so cool to the touch I can hold my hand on it without a problem. I have "burped" the system, flushed the radiator and flushed the engine. What would you guys suggest is my issue?

The engine is a stock 350 in a 72 Chevy with auto trans.