Thermostat
ThermostatNOTE: Overheating or failure to reach normal operating temperature can indicate incorrect thermostat operation. Inspection and temperature-testing of the water thermostat will verify its condition.
NOTE: Insufficient heat and failure of the engine to reach operating temperature can indicate low temperature leakage of the water thermostat. Cool the water thermostat to room temperature for this inspection.
1. Remove the water thermostat.
2. Hold the thermostat against a lighted background and inspect for light between the valve and valve seat. If light is visible, install a new thermostat.
Thermostat-Mechanical Test
1. Suspend the water thermostat and an accurate thermometer in a suitable container filled with water. Do not allow the water thermostat and the thermometer to touch the bottom of the container.
2. Heat the water until boiling while observing the thermometer temperature.
3. NOTE: "Fully open" means the water thermostat valve lifts a distance of 5.8 mm (0.23 inch) or more off of the valve seat.
The water thermostat should begin to open at 90° - 94° (194° - 201 °F).
4. The water thermostat should be fully open at 106°C (223°F).
5. Install a new water thermostat if it does not operate as specified.