A fan clutch is featured on rear wheel drive cars only because it connects to the water pump and faces the radiator while pulling air through the radiator's cooling fins when the engine is operating. The fan clutch freewheels while the engine is cold and then starts to work when the engine gets hot and requires the aid of the fan to keep the engine from overheating.
As with all automotive parts they can go bad due to heat, usage and engine vibration. When a fan clutch goes bad it can do so by permanently freewheeling allowing the engine to overheat or it can lockup causing a loud roaring sound and decreased engine power output.
When having your car's fan clutch replaced at a garage or dealer it can cost between $155.00 and $290.00 (US) depending on the design and the manufacturer of the car. But when you do the job yourself with the help of our guide you can buy the fan clutch from Amazon for between $36.00 and $155.00 (US). You will also need a special tool to remove the part if you don't have one already which will be about $20.00 from Amazon as well.
Video of this job being done at the bottom of this guide.
1. Identify the Nut Size
Each fan clutch will have its own mounting nut size which will range from 22mm to 36mm depending on the application and manufacturer. You can also use a large adjustable wrench if you do not have the proper tool. You may need to remove the fan shroud to get at the cooling fan.
2. Hold the Water Pump Pulley
You must hold the water pump pulley in order to remove the fan clutch from the water pump. They make a special tool for this which you can get from Amazon for about $20.00 bucks or you can rent one for free from your local auto parts store. We loaned out our tool for this job and are waiting for its return so in the meantime we have this large pipe wrench which we were able to sneak onto the pulley to hold it for removal.
This is what the proper tool kit looks like to remove most fan clutches which cost about $80.00 on Amazon. You can get the one specifically for your car for about $20.00 from Amazon as well.
3. Remove the Fan Clutch
Next we installed a large crescent wrench onto the fan clutch nut. Then we hit it with a hammer to loosen the fan. If you are ever wondering which way to loosen the fan nut (some are reverse thread) it will always loosen in the same direction as the fan turns when the engine is running.
Once the fan is loose simply keep rotating the fan in the same direction while watching the threads to make sure the fan clutch in turning without the nut. If the nut is not turning use the wrench to help it along. Use your opposite hand to support the fan blade so it does not hit the radiator and cause a leak when the fan becomes loose. That would take the fun out of the job. The image below shows the two handed removal method.
4. Replace the Fan Clutch
There will be four to six 10mm bolts that will hold the actual clutch part of the fan to the fan blade itself. Remove these nuts and the clutch will come free from the blade. Once you have matched up the old fan clutch to the new unit reassemble it by installing and tightening the nuts in a cross pattern.
5. Reinstall the Fan Clutch
Once the new part has been installed gently slip the fan clutch down in front of the water pump using caution as to not contact the radiator or damage the plastic fan blade.
The threads on the water pump flange are large and can be cross threaded easily so we advise you to start the fan nut by hand before taking a wrench to it. This will eliminate any change of hurting the threads in which case the water pump would need to be replaced. Steady the fan by holding the center of the clutch while watching the threads to make sure you are square to the the water pump. Once threaded on insert the large wrench or tool to finish installing the fan clutch onto the threads and then and tap the fan to completely tighten it and you are all set.
Here is a video of the job being done by one of our mechanics.