Immerse the thermostat in water and gradually heat the water.
Check the valve opening temperature.
If the valve opening temperature is not as specified, replace the thermostat.
Valve opening temperature:
88 ± 1.5°C (190.4 ± 34.7°F)
Full opening temperature: 100°C (212°F)
Check the valve lift.
If the valve lift is not as specified, replace the thermostat.
Valve lift : 8 mm (0.3 in.) or more at 100°C (212°F)