How do you test a viscous hub?

When your motor is hot, you should be able to hear the fan kick in. If you can’t, pop the bonnet, and turn the vehicle off while watching the fan. If it comes to a fairly abrupt stop, the fan hub is working properly. If it keeps spinning round and round, your fan hub is knackered and needs to be repaired or replaced.

How do you diagnose a bad viscous fan?

To confirm the diagnosis, start with this simple test: Spin the fan as hard as you can on an engine that has not been started that day. If the fan rotates more than five times, you can bet the clutch is bad. You should feel some resistance and the fan may spin up to three times, depending on the ambient temperature.

Should a viscous fan spin freely?

The fan clutch is responsible for transferring power from the drive belt or the water pump pulley to the fan, but should it be spinning freely when cold? The viscous fan clutch will, with some resistance, spin freely when cold.

How do I test my fan clutch?

What are the symptoms of a bad fan clutch?

How to Tell If Your Fan Clutch Is Going Bad?

Vehicle overheating. An overheating engine is often the first symptom that is commonly associated with a bad or failing fan clutch.
Loose and Wobbling Fan.
Excessively loud cooling fans.
A decrease in acceleration, power & fuel efficiency.

How do viscous fans fail?

Leaking silicone fluid, disengaging the fan coupling. Bimetal sensor losing its properties due to surface oxidation, causing the coupling to be stuck disengaged. Bearing failure, although uncommon can occur if the viscous fan coupling has not been replaced after high mileage.

How do I know if my fan clutch needs to be replaced?

How to Tell If Your Fan Clutch Is Going Bad?

Vehicle overheating. An overheating engine is often the first symptom that is commonly associated with a bad or failing fan clutch.
Loose and Wobbling Fan.
Excessively loud cooling fans.
A decrease in acceleration, power & fuel efficiency.

How do you test a viscous hub?