Mechanical

NOTE: Fully open means the thermostat valve lifts a distance of 5.8mm (0.2 inch) or more off the valve seat.

Remove the water thermostat and immerse in a boiling antifreeze and water mixture. The water thermostat should begin to open at 86-90°C ( 187-194°F) 2.0L engine, 84-88°C (183-190°F) 2.5L engine and be fully open at 102°C (216°F) 2.0L engine, 99°C (210°F) 2.5L engine. Install a new thermostat if it does not operate as specified.

If heat is not available, check the water thermostat for leakage. Hold the water thermostat up to a lighted background. Leakage of light around the thermostat valve at room temperature indicates that the water thermostat should be replaced. Some water thermostats have a small leakage notch at one location on the perimeter of the thermostat valve, which is considered normal.