What Are the Signs That Your Fan Clutch Is Going Bad?by Steven Symes
Some engine fans are controlled by a belt attached to the car's engine, meaning the faster the engine goes the more the fan spins. Other fans have a spring that is temperature sensitive, causing the fan to spin more as the air gets hotter. The fan clutch helps transfer the energy from either the spring or the engine belt to the fan, causing the fan to turn at a certain speed.
A fan clutch that is going bad can create one huge sign that something is wrong: overheating of the engine. While most drivers recognize the signs of an overheating engine, many do not immediately think of the fan clutch as the cause. A bad fan clutch will cause the fan to not operate as it should. An engine fan not doing its job well can increase the temperature in the engine, leading to potential engine damage.
A failing fan clutch can actually cause the engine fan to become loose and wobble. Sometimes this wobble can be heard while driving, especially at freeway speeds. You can turn on your car's engine while the vehicle is in park or neutral, pop the hood, and see for yourself that the fan is wobbling as it spins. Also, drivers should check for signs of oil coming out from the clutch hub.
A fan clutch that is going bad can cause the fan to not spin as quickly as normal. If you park your car and have another person rev the engine while you look under the hood, you may notice the engine fan speeds up only a little. Under normal circumstances, the fan speeds up quite a bit as the engine revs.