Immerse the thermostat in water and gradually heat the water.
Check the valve opening temperature.
Valve opening temperature: 82°C (177°F)
Full opening temperature: 95°C (205°F)
If the valve opening temperature is not as specified, replace the thermostat.
Check the valve lift.
Valve lift : 8mm (0.3in.) or more at 95°C (205°F)
If the valve lift is not as specified, replace the thermostat.