1997 Monte Carlo overheats heat cuts on and off tryed replacing thermostat radiator cap flushed radiator thermo stuck shut so block not flushed still not working?

Answer 1

The coolant system is made up of many parts, I'll list the important ones first:

1) Thermostat

2) Water Pump

3) Radiator and Cap(s)

4) Hoses/Coolant Lines

5) Ports within the engine block for coolant flow

T-Stats, purchased from local auto shops, and sometimes even dealers, are not necessarily good right out of the box. In other words, in my experience, only 3 out of 5 T-Stats are NOT defective. My first guess, try another T-Stat as the first one you bought is defective.

Verify that the radiator and coolant lines are not leaking.

Finally, if the T-Stat is opening and there are no leaks, you need a NEW Water Pump.