Cooling Fan Assembly

Removal and replacement of the engine cooling fan assembly, including the fan clutch and fan blade on the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Cooling fan blade × 1 — Use OEM specification
• Thermal fan clutch × 1 — Use OEM specification
• Upper radiator hose clamps (if damaged) × 2 — Use OEM specification

Fluids

• HOAT coolant 50/50 — 1 qt

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery cable
4. Place drain pan under radiator to catch any coolant spillage
5. Remove engine cover if equipped

Procedure

1. 1

   Remove upper radiator shroud
   Remove the upper radiator shroud by removing the mounting fasteners along the top edge (verify fastener type and size, commonly clips or bolts). Confirm the number of fasteners securing the upper shroud to the radiator support and lower shroud. Carefully lift the upper shroud up and away from the radiator, tilting it as needed to clear the fan assembly.
2. 2

   Access the fan clutch nut
   Locate the large 36mm fan clutch nut at the center of the fan assembly where it threads onto the water pump pulley. Position yourself to access the nut from above the engine. Note the direction of the threads - this is a standard RIGHT-HAND threaded connection on the Cummins water pump shaft.
3. 3

   Secure the water pump pulley
   Use a fan clutch holding tool or strap wrench to secure the water pump pulley and prevent it from rotating. If using a strap wrench, wrap it around the pulley in a manner that will hold the pulley stationary while you turn the fan clutch nut counterclockwise to loosen it. The serpentine belt may provide some resistance, but additional holding is typically required.
4. 4

   Loosen the fan clutch nut
   Using the 36mm fan clutch wrench, turn the fan clutch nut COUNTERCLOCKWISE to loosen (standard right-hand threads). A sharp impact or steady pressure may be needed to break it loose as these are typically very tight. Once broken free, continue turning counterclockwise until the nut can be removed by hand. Remove the nut completely.
   ⚠Use controlled force to avoid slipping and striking knuckles on radiator or other components.
5. 5

   Remove fan clutch and blade assembly
   Carefully pull the fan clutch assembly straight off the water pump shaft. The assembly is heavy and awkward. Tilt the fan blade assembly as needed to maneuver it out from between the radiator and engine, being extremely careful not to damage the radiator fins or strike the radiator core. It may be helpful to rotate the fan to find the best angle for removal.
6. 6

   Separate fan blade from clutch (if replacing individually)
   If replacing only the fan blade or only the fan clutch, separate the two components. The fan blade is secured to the fan clutch with mounting bolts (verify count and size against service documentation). Remove these bolts with the appropriate socket while holding the fan blade steady. Inspect both components for damage, cracks, or excessive wear. Check the fan clutch for fluid leaks or seized operation.
7. 7

   Inspect water pump shaft and pulley
   With the fan assembly removed, inspect the water pump shaft threads for damage or debris. Clean the threads with a wire brush if necessary. Check the water pump pulley for wobble or damage. Inspect the water pump for any signs of coolant leakage from the weep hole, which would indicate impending water pump failure.
8. 8

   Install new or serviced fan assembly
   If fan blade was separated from clutch, assemble the new or reused components together, securing the fan blade to the clutch with the 4 mounting bolts. Carefully guide the assembled fan clutch and blade into position between the radiator and engine, taking care not to damage the radiator. Thread the fan clutch onto the water pump shaft by hand, turning CLOCKWISE (standard right-hand threads). Ensure it threads on smoothly without cross-threading.
9. 9

   Torque the fan clutch nut
   Secure the water pump pulley again with the holding tool or strap wrench. Using the 36mm fan clutch wrench, tighten the fan clutch nut by turning CLOCKWISE. Tighten firmly per manufacturer specification (verify the exact torque in the service manual, as the fan clutch mounting hub torque differs from a standard fastener). The fan clutch must be secure as vibration can cause loosening.
10. 10

    Verify fan blade clearance
    Before reinstalling the shroud, manually rotate the fan blade through its full range of motion. Verify there is adequate clearance between the fan blade tips and the radiator core (minimum 1 inch). Check clearance to any hoses, wiring, or other components. If the fan contacts anything, investigate before proceeding.
11. 11

    Reinstall upper radiator shroud
    Position the upper radiator shroud back into place, ensuring the fan blade is properly centered within the shroud opening. Install all mounting bolts and tighten securely with the 10mm socket. Ensure the shroud is properly seated and aligned with the lower shroud.
12. 12

    Reconnect battery and check coolant level
    Reconnect the negative battery cable. Check the coolant level in the overflow reservoir and add HOAT 50/50 coolant as needed to bring it to the proper level. Some coolant may have been lost during the procedure.

Reassembly

1. Reinstall engine cover if it was removed
2. Double-check that all tools have been removed from the engine compartment
3. Verify all shroud mounting bolts are tight and the shroud is properly seated

Verification

• Start the engine and allow it to idle, listening for any unusual noises from the fan area
• Verify the fan clutch engages as the engine warms up (fan speed will increase and become audible)
• Check for any vibration or wobble in the fan assembly at idle and elevated RPM
• Verify no coolant leaks are present around the water pump or hoses
• Confirm adequate clearance between fan blade and radiator with engine running
• Allow engine to reach operating temperature and verify cooling fan operates properly

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle