Inspect Thermostat

1. Immerse the thermostat in water and gradually heat the water.
2. Check the valve opening temperature.

   Valve opening temperature: 80 - 84°C (176 - 183°F) 

   If the valve opening temperature is not as specified, replace the thermostat.

   Fig 1: Checking Valve Opening Temperature

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Check the valve opening lift.

   Valve lift: 8 mm (0.31 in.) or more at 95°C (203°F) 

   If the valve lift is not as specified, replace the thermostat.

4. Check that the valve is fully closed when the thermostat is at low temperatures (below 40°C (104°F)).
   Fig 2: Checking Valve Opening Lift

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

If not closed, replace the thermostat.