Engine Overheating

Inspect for engine overheating as follows:

1. Start with a cool engine to ensure complete fan clutch disengagement.
2. If the fan/fan clutch assembly free-wheels with no drag (revolves more than five times when spun by hand), replace the fan clutch. Testing a fan clutch by holding the small hub with one hand while rotating the aluminum housing in a clockwise/counterclockwise motion will cause the clutch to free wheel. This is a normal condition when operated this way. It is not a test to determine replacement.
3. Position a thermometer between the radiator and the fan blades. Do this by inserting the thermometer sensor through one of the existing holes in the fan shroud, or by placing it between the radiator and the shroud.
4. With the thermometer in position, cover the radiator grille enough to induce a high engine temperature. Start the engine. Turn the air conditioning on. Run the engine at 200 RPM.
5. It takes approximately 5-10 minutes for the temperature to become high enough to allow engagement of the fan clutch. This will be indicated by an increased in roar in the fan air noise. There also will be a drop in the temperature reading, from 3-15°C, (5-15°F).
   • If the clutch does not engage between 65-90°C (150-195°F), the fan clutch should be replaced. Be sure the fan clutch is disengaged at the start of the test.
   • If the fan noise level is constantly high from the start of the test to 88°C (190°F), without any noticeable noise level increase or drop in temperature, the fan clutch must be replaced. To prevent engine overheating, discontinue the test, past a thermometer reading of 88°C (190°F).
6. As soon as the clutch engages, remove the radiator grille cover. Next turn off the air conditioning. This will assist in engine cooling. Run the engine at approximately 1500 RPM.