Fan Belt Replacement

This procedure covers removal and replacement of the serpentine belt on the 5.9L Cummins diesel engine, including tensioner inspection and proper belt routing verification.

Warnings

Tools required

Parts

• Serpentine belt × 1 — Gates K060965 or equivalent (varies by A/C configuration)
• Belt tensioner assembly — Replace if worn or seized - inspect during procedure

Preparation

1. Park vehicle on level surface, set parking brake, and chock rear wheels
2. Allow engine to cool completely (minimum 1 hour after operation)
3. Disconnect negative battery cable to prevent accidental starter engagement
4. Take a clear photo of the belt routing or sketch the routing pattern before removal
5. Verify the belt routing diagram on the fan shroud or radiator support is legible for reference

Procedure

1. 1

   Access the serpentine belt
   Open the hood and secure with the prop rod. Identify the automatic belt tensioner assembly mounted on the front of the engine, typically near the top center/passenger side area of the accessory drive. The tensioner pulley is spring-loaded and maintains automatic belt tension. Locate the 3/8" square hole in the tensioner arm for inserting a breaker bar.
2. 2

   Inspect belt routing and components
   Before removal, verify your belt routing documentation matches the actual installation. Inspect all pulley surfaces for damage, misalignment, or excessive wear. Check the tensioner pulley for smooth rotation without play or noise. Examine the idler pulley (if equipped) for the same conditions. Note any issues for component replacement.
3. 3

   Release belt tension
   Insert a 3/8" breaker bar or serpentine belt tool into the square hole on the tensioner arm. Rotate the tensioner in the direction that unloads the spring (confirm direction on your specific engine) to release tension on the belt. The spring tension is significant; maintain firm control of the breaker bar. Hold the tensioner in the released position.
4. 4

   Remove the old belt
   While holding the tensioner in the released position, slip the belt off the nearest pulley (typically the alternator or water pump pulley). Slowly release the tensioner back to its resting position. Remove the belt from the remaining pulleys and extract it from the engine bay. Avoid forcing the belt past the cooling fan if clearance is tight.
5. 5

   Inspect tensioner and pulleys
   With the belt removed, manually rotate the tensioner pulley and check for roughness, binding, or lateral play indicating worn bearings. The pulley should spin freely and quietly. Inspect the smooth face of the pulley for glazing, cracks, or grooves. Check that the tensioner arm moves smoothly through its full range and returns to the proper position under spring tension. If any component shows wear, proceed with replacement before installing the new belt.
6. 6

   Replace tensioner components if necessary
   If the tensioner assembly requires replacement, remove the mounting bolt(s) securing the tensioner to the engine (fastener count and size vary by year; verify against service documentation). If replacing only the tensioner pulley, remove the center bolt. Clean mounting surfaces with a wire brush. Install the new component(s) and torque the mounting bolts or pulley bolt to specification. Verify smooth operation before belt installation.
   Torque spec

   Tensioner Pulley Bolt45 Nm (33 lb-ft)
7. 7

   Route the new belt
   Begin routing the new serpentine belt according to your documented routing pattern or the underhood diagram. Route the belt according to the underhood belt routing diagram for your specific vehicle and A/C configuration, as routing varies. Ensure the belt ribs seat in the grooved pulleys and the smooth backside contacts any flat/idler pulleys. Do NOT place the belt on the tensioner pulley yet. Ensure the belt ribs are properly seated in all pulley grooves.
8. 8

   Install belt onto tensioner
   Insert the breaker bar into the tensioner arm and rotate in the direction that unloads the spring (confirm direction) to release tension, creating slack in the system. Route the belt over or under the tensioner pulley (confirm direction from your routing diagram). Verify the belt is properly seated in the tensioner pulley grooves. Slowly release the tensioner, allowing the spring tension to load the belt. Remove the breaker bar.
9. 9

   Verify belt installation
   Visually inspect all pulleys to confirm the belt ribs are fully seated in each pulley's grooves with no overlap or misalignment. Check that the belt is not twisted anywhere in its path. Manually rotate the crankshaft pulley two complete revolutions clockwise (using a socket on the crankshaft bolt) while watching the belt path. The belt should track smoothly without slipping, jumping, or contacting any non-pulley surfaces.
10. 10

    Test belt operation
    Reconnect the negative battery cable. Start the engine and allow it to idle. Listen for unusual squealing, chirping, or slapping noises that indicate improper tension or misalignment. Observe the belt operation for 30-60 seconds, watching for any unusual vibration or tracking issues. Shut off the engine and perform a final visual inspection to confirm the belt remains properly seated.

Reassembly

1. Ensure the negative battery cable is reconnected and secured
2. Verify all tools and parts have been removed from the engine compartment
3. Close and secure the hood

Verification

• Start the engine and verify no belt noise or vibration is present at idle and at 1500-2000 RPM
• Confirm all belt-driven accessories operate correctly: alternator charging, power steering assist, air conditioning compressor engagement (if equipped)
• After the first 100-200 miles of operation, visually re-inspect the belt for proper seating and check for any signs of abnormal wear or fraying
• Verify the belt tensioner maintains proper tension without the belt appearing loose or over-tightened

More procedures for this vehicle