Fan Clutch Troubleshooting Tips
When a fan clutch fails it causes problems with prevalent engine action. There are two ways the clutch will fail. The fan will stop and the engine can overheat, or the fan will run constantly and will decrease gas mileage and horsepower. Determining if a fan clutch has failed or not can solve a handful of engine problems.
Understand Your Fan Clutch
A seized fan will not spin at all, or will provide a lot of resistance indicating a failed clutch. If the fan spins freely or with very little resistance, the clutch has failed to engage at all. Either of these would need replacement.
If a fan clutch fails, it will fail in one of two ways: it will seize up and run continuously, or it will fail to engage and the fan will not spin. If your clutch seizes, the fan will run continuously and will cause excess fan noise, decreased horsepower and decreased gas mileage. If the fan fails to spin at all, the engine will run hotter than it should.
Narrow the Possibilities
Pay close attention to the temperature of your engine and the amount of fan noise coming from your engine when you're driving or parked. If your engine seems to be running hot and you don't hear any fan noise, you may have a clutch that is failing to engage. If your engine does not seem to be overheating, or it is running cool, and your fan seems to be making a lot of noise, then you may have a clutch that has seized.
Take a Look
With the engine has stopped and is cool, take a look at the fan and clutch. A broken or damaged fan can cause engine cooling problems, and needs to be ruled out before continuing further. Oil leaking from the fan clutch itself is an indication of failure. Oil leaked from the fan clutch may be dripping or may be sprayed out in a radial fashion, both of which are bad.
Diagnosis
With the engine stopped and cool, try to spin the fan blade with your hand. A functioning clutch will provide some resistance, but not a lot (between one half and two rotations).A good fan clutch engages a fan that pulls air across the radiator, keeping your engine cool. The clutch will change fan speed depending on the engine temperature. What you are looking for is any deviation in this behavior.
