Step by step guide on how an automotive fan clutch works. This article pertains
to all vehicles equipped with a clutch fan.
- A fan clutch function is to engage the
fan blade to the shaft when heated which is mounted to the front of the engine attached
to the water pump. This clutch is constructed using silicone grease, and a temperature
sensitive coil spring that expands and contracts with heat from the radiator.
Step 2 - The fan clutch is driven from a
which is connected to the main drive pulley of the engine.
Step 3 - To remove the fan clutch a large wrench
is needed, it might also require a hammer "shock" to unlock the clutch threads.
These threads can be standard or reverse rotation.
A clutch fan can fail one of two ways, it can either be locking the fan to the
clutch causing poor mileage and a whirring sound, (like an airplane is taking off.)
Or the silicone grease can leak out causing the fan clutch not to lock up, allowing
the fan to "freewheel", failing to pull air through the radiator, this failure usually
is followed by the engine overheating. The clutch fan is utilized at slower speeds
while air movement is diminished.
(Engine "OFF".) Inspect the fan clutch for leakage from the front or rear of
the unit, input shaft and temperature controlled expansion spring. If leakage is
observed, the fan clutch has failed. Next, grasp the fan blade and turn it, the
fan blade should free wheel with some resistance. If the blade spins with no resistance,
or doesn't spin at all, the clutch has failed.
A clutch fan was developed in the late 1960's and was in full production by the
early 1970's. Prior to the clutch fan, an engine was subject to a fixed style of
fan that was directly bolted onto the engine. This direct style of fan is not only
inefficient, it produced excess noise that was undesirable.
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Fan Clutch Removal
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Article first published 2016-02-04