What is a fan clutch?

A fan clutch is a thermostatic engine cooling fan that can freewheel at low temperatures when cooling is not needed, allowing the engine to warm up faster, relieving unnecessary load on the engine. As temperatures increase, the clutch engages so that the fan is driven by engine power and moves air to cool the engine.

Most fan clutches are viscous or "fluid" couplings, combined with a bi-metallic sensory system similar to that in a thermostat. Some clutches are electronically controlled (instead of bi-metallic strip). These provide the potential to control the level of engagement depending on any number of inputs. Common controlling factors might include engine oil temperature, transmission oil temperature, coolant temperature, AC system pressures and ambient air temperature.

How to detect a faulty fan clutch?

-Fan spins excessively when engine is stopped.

-Poor A/C performance at idle or low vehicle speeds.

-Fan speed does not increase when engine is hot.

-Fan speed does not increase until engine is excessively hot.

-Fan blade tip moves more than 1/4” front to back.

-Fan turns roughly or does not turn at all.

-Excessive fan noise at all speeds due to failed bearing.

-Vibration that increases with engine speed.

How to replace a fan clutch?

Materials Needed

-Pulley locking tool

-Wrench

-Socket set with ratchet

-Rubber mallet

Step 1: Remove the fan shroud. Because every application is different, some of these steps may need to be altered in order to fit your specific application. On most applications, however the fan shroud is fastened by several bolts which will need to be removed in order to remove the shroud. Most applications will also require removal of the top radiator hose in order to get the fan shroud out. If this is the case, be sure to drain your coolant system prior to doing this. Once this is done, you can remove the fan shroud from the engine compartment.

Step 2: Remove the fan. There are typically two types of ways the fan will be attached; one will be with four large bolts, in which case you will need just a basic wrench of the appropriate size to remove. The other method of attachment is a large nut that will likely require the use of a special pulley locking tool that is used to keep the pulley from moving while removing the nut.

Since this is a specialty tool, most people may not have access to this tool. If this is the case, an alternative to using this specialty tool can be the use of a screwdriver. Use the screwdriver to hold keep the bolt in place while loosening the nut. Pay special attention to the placement of the screwdriver while doing this as this can damage the edges of the bolts if not done properly.

Step 3: Rock from side to side. Once all bolts and/or nuts have been removed, hold the fan with both hands slightly rocking it from side to side sliding it off of the water pump shaft.

Step 4: Remove the bolts. Secure the fan on a work table with plenty of room to work with the fan shaft facing your direction. There are four large bolts in the center of the fan assembly that hold the clutch in place. Remove these bolts and the clutch will be free from the fan.

Step 5: Install the new fan clutch. Hold the new fan clutch in place aligning the bolt holes in the same place as the old clutch.

Lightly run the bolts into the holes making sure the threads are lining up properly

Tip: The bolts should run into the threads freely with little or no resistance. If they feel tight or like you are using too much force, you are likely cross threading them which can lead to the bolts not staying in tightly and eventually falling out. Note, this is extremely important.

Step 6: Tighten the bolts. Once you’ve run all bolts in finger tight, use your wrench to tighten them according to factory specifications (refer to your service manual or instructions with the new fan clutch).

Step 7: Put the fan back into the engine. Slide the fan assembly back into the engine compartment paying special attention to the water pump shaft alignment.

Once in place, gently run the four bolts back into place holding the fan with one hand and running the bolts back in with the other. This may take some maneuvering to keep things straight, but remember, slow and steady and paying attention to detail is important.

When all four bolts are back in place and run in finger tight, use the same wrench you used to remove them with to tighten them back up according to factory specifications (Again, refer to your service manual for exact specifications).

If your application requires you to remove the top radiator hose to get the fan shroud out, now would be the time to reinstall that same radiator hose. Be sure to also remember to refill your coolant system if draining it was part of the removal process.

Slide the fan shroud back into place lining up the bolt holes in the same position as it was removed. Run each bolt back in finger tight until all are accounted for and tighten per factory specifications (Refer to service manual for torque specs).

You have now replaced your fan clutch. A good practice as always is to start the vehicle and listen for abnormal noises and watch for movements in the replacement parts that are not consistent.

What is a fan clutch?

A fan clutch is a thermostatic engine cooling fan that can freewheel at low temperatures when cooling is not needed, allowing the engine to warm up faster, relieving unnecessary load on the engine. As temperatures increase, the clutch engages so that the fan is driven by engine power and moves air to cool the engine.

Most fan clutches are viscous or "fluid" couplings, combined with a bi-metallic sensory system similar to that in a thermostat. Some clutches are electronically controlled (instead of bi-metallic strip). These provide the potential to control the level of engagement depending on any number of inputs. Common controlling factors might include engine oil temperature, transmission oil temperature, coolant temperature, AC system pressures and ambient air temperature.

How to detect a faulty fan clutch?

-Fan spins excessively when engine is stopped.

-Poor A/C performance at idle or low vehicle speeds.

-Fan speed does not increase when engine is hot.

-Fan speed does not increase until engine is excessively hot.

-Fan blade tip moves more than 1/4” front to back.

-Fan turns roughly or does not turn at all.

-Excessive fan noise at all speeds due to failed bearing.

-Vibration that increases with engine speed.

How to replace a fan clutch?

Materials Needed

-Pulley locking tool

-Wrench

-Socket set with ratchet

-Rubber mallet

Step 1: Remove the fan shroud. Because every application is different, some of these steps may need to be altered in order to fit your specific application. On most applications, however the fan shroud is fastened by several bolts which will need to be removed in order to remove the shroud. Most applications will also require removal of the top radiator hose in order to get the fan shroud out. If this is the case, be sure to drain your coolant system prior to doing this. Once this is done, you can remove the fan shroud from the engine compartment.

Step 2: Remove the fan. There are typically two types of ways the fan will be attached; one will be with four large bolts, in which case you will need just a basic wrench of the appropriate size to remove. The other method of attachment is a large nut that will likely require the use of a special pulley locking tool that is used to keep the pulley from moving while removing the nut.

Since this is a specialty tool, most people may not have access to this tool. If this is the case, an alternative to using this specialty tool can be the use of a screwdriver. Use the screwdriver to hold keep the bolt in place while loosening the nut. Pay special attention to the placement of the screwdriver while doing this as this can damage the edges of the bolts if not done properly.

Step 3: Rock from side to side. Once all bolts and/or nuts have been removed, hold the fan with both hands slightly rocking it from side to side sliding it off of the water pump shaft.

Step 4: Remove the bolts. Secure the fan on a work table with plenty of room to work with the fan shaft facing your direction. There are four large bolts in the center of the fan assembly that hold the clutch in place. Remove these bolts and the clutch will be free from the fan.

Step 5: Install the new fan clutch. Hold the new fan clutch in place aligning the bolt holes in the same place as the old clutch.

Lightly run the bolts into the holes making sure the threads are lining up properly

Tip: The bolts should run into the threads freely with little or no resistance. If they feel tight or like you are using too much force, you are likely cross threading them which can lead to the bolts not staying in tightly and eventually falling out. Note, this is extremely important.

Step 6: Tighten the bolts. Once you’ve run all bolts in finger tight, use your wrench to tighten them according to factory specifications (refer to your service manual or instructions with the new fan clutch).

Step 7: Put the fan back into the engine. Slide the fan assembly back into the engine compartment paying special attention to the water pump shaft alignment.

Once in place, gently run the four bolts back into place holding the fan with one hand and running the bolts back in with the other. This may take some maneuvering to keep things straight, but remember, slow and steady and paying attention to detail is important.

When all four bolts are back in place and run in finger tight, use the same wrench you used to remove them with to tighten them back up according to factory specifications (Again, refer to your service manual for exact specifications).

If your application requires you to remove the top radiator hose to get the fan shroud out, now would be the time to reinstall that same radiator hose. Be sure to also remember to refill your coolant system if draining it was part of the removal process.

Slide the fan shroud back into place lining up the bolt holes in the same position as it was removed. Run each bolt back in finger tight until all are accounted for and tighten per factory specifications (Refer to service manual for torque specs).

You have now replaced your fan clutch. A good practice as always is to start the vehicle and listen for abnormal noises and watch for movements in the replacement parts that are not consistent.