The viscose fan is attached to the water pump and designed to cut in and out depending on the temperature of the water. The fan will last at least 5 years or 100,000Kms. After this the fan should be checked periodically every 10,000Kms for its effectiveness. The viscose fan is a fluid substance that changes its viscosity depending on the heat, allowing the fan to freely move or lock up on a one to one ratio with the pulley.
THINGS TO LOOK FOR
A viscose fan should cut in and out, if monitored over 1/2 hr of the engine idling. Use extreme caution with the viscose fan or any fan blade when checking. The best way to check the fan is to idle the engine for about 1500 revs per minute to 2000 and you will notice when revving the engine while hot, more of a fan noise will be apparent. Then when the cooling system cools down the viscose fan is not consuming any energy from the fan belt or water pump pulley. A viscose fan may also cause the engine to overheat at moderate to high speed.
IS IT EXPENSIVE TO REPAIR?
Viscose fans may be expensive to repair depending on the make and model. It’s always a good idea to replace a viscose fan with the original type. They could cost around $150.00. Getting one from the wreckers is not recommended as most of these fans are faulty.
TEMPORARY REPAIR AND LONG TERM REPLACEMENT
If you are stranded and the fan is locking up, cooling the radiator, then you can try overhauling the viscose fan and putting a bolt in to prevent it from free wheeling just to get you around. But it does affect your fuel economy.