K 1500 Truck 4WD V8-5.7L VIN R (1997)
Thermostat: Initial Inspection and Diagnostic Overview
Perform an operational check of the thermostat by hanging the thermostat on a hook in a 33% glycol solution, -12°C (10°F) below the temperature
indicated on the valve. With the valve submerged and the coolant agitated, the valve should close. Refer to the thermostat diagnosis chart for detailed
thermostat diagnostic procedures.