Immerse the thermostat in water and gradually heat the water.
Check the valve opening temperature.
Valve opening temperature : 82 ± 2°C (179.6 ± 3.6°F)
Full opening temperature : 95°C (203°F)
If the valve opening temperature is not as specified, replace the thermostat.
Check the valve lift.
Valve lift :
10 mm (0.3937 in) or more at 95°C (203°F)
If the valve lift is not as specified, replace the thermostat.