Thermostat Test

Replace the thermostat if it is stuck open at room temperature.

To test a closed thermostat:

1. Suspend the thermostat (A) in a container of water. Do not let the thermometer (B) touch the bottom of the hot container.
   Fig 1: Checking Thermostat Operation

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
2. Heat the water and check the temperature with a thermometer. Check the temperature when the thermostat first opens, then check the temperature when the thermostat is fully open.
3. Measure the lift height of the thermostat when it is fully open.

   Standard Thermostat: 

   Lift Height: Above 10.0 mm (0.39 in.) 

   Starts Opening: 169-176°F (76-80°C) 

   Fully Open: 194°F (90°C)