For 1990-2009 cars only
- Remove the thermostat from the vehicle. Refer to Engine Coolant Thermostat Replacement .
- Make sure the valve spring is tight when the thermostat is fully closed. If the spring is not tight, replace the thermostat.
- Suspend the thermostat and a thermometer in a pan of 50/50 mixture of ethylene glycol and water.
- Heat the pan on a burner.
- Use the thermometer to measure the temperature of the heated solution.
- The thermostat should begin to open at 82°C (180°F) and it should be fully open at 95°C (203.4°F). It should be fully closed at 80°C (176.4°F). If it does not open or close at these temperatures, replace the thermostat. Also, the thermostat rod's stroke from the initially open to the fully open should be 8 mm (0.31 in).
Important: Do not let the thermostat or the thermometer rest on the bottom of the pan because the uneven concentration of heat on the bottom could result in inaccurate temperature measurements.
