Noise
Sometimes there is fan noise under the following conditions:
| • | The clutch is engaged for maximum cooling |
| • | The first 15 seconds to one minute after start-up. Until the clutch
can redistribute the silicone fluid to its normal disengaged operating condition
(after settling 2-4 hours). |
Fan noise or an excessive roar generally occurs under all high-speed
conditions (2,500 RPM or higher) if the clutch assembly is locked up
due to internal failure. If the fan cannot be rotated by hand or there is
a rough grating feel as you turn the fan. Replace the clutch, refer to
Fan Clutch Replacement
.
Looseness
Check a loose fan assembly for wear. Replace a worn assembly as necessary.
Under various temperatures, there is a visible lateral movement at the tip
of the fan blade. Allow approximately 6.5 mm (¼ in) maximum
lateral movement measured at the fan tip. More movement, is cause for replacement.
Silicone Fluid Leaks
Small fluid leaks around the bearing assembly will not affect the fan
clutch operation. If the leakage appears excessive, replace the fan clutch.
Refer to
Fan Clutch Replacement
.
Engine Overheating
Check for engine overheating as follows:
| • | Start with a cool engine to ensure complete fan clutch disengagement. |
| • | 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. |
Caution: Do not use or attempt to repair a damaged cooling fan assembly. Replace
damaged fans with new assemblies. An unbalanced cooling fan could fly apart
causing personal injury and property damage.
| • | 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. |
| • | 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 2000 RPM. |
| • | 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). |
| • | 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. |
| • | After several minutes, the fan clutch should disengage. There
will be a reduction in fan speed with decreased fan noise. If the fan clutch
fails to function as described, you must replace the fan clutch. |
