340 Overheating Help

STOP!!!!!

If you are getting a 200 degree reading inside the radiator, most likely everything is OK and the gauge is your problem.

Start the car while it is "overnight cold" and feel the upper hose near the radiator neck while someone watches the gauge. You could also set up a mirror to watch this for yourself. Look where the needle is when the hose gets hot. If you have a 180 thermostat, the needle will be indicating 180 when the hose gets hot, as this is the thermostat opening for the first time.

You could also try an infrared temp gun, if you know anyone with one. Aim it at the upper hose or thermostat housing while the motor is running and up to normal temp.