This procedure covers the removal and installation of the serpentine belt on the 6.7L Cummins diesel engine, including proper belt routing and tensioner operation.

Warnings

Tools required

Parts

• Serpentine belt (8 rib) × 1 — Use OEM specification or Gates K080975
• Belt tensioner assembly (if worn) × 1 — Use OEM specification
• Idler pulley (if worn) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely
3. Disconnect negative battery cable to prevent accidental engine start
4. Photograph or sketch the serpentine belt routing for reference during installation
5. Inspect belt tensioner and idler pulleys for wear, noise, or roughness while belt is accessible

Procedure

1. 1

   Access the serpentine belt
   Open the hood and locate the serpentine belt at the front of the engine. On the 6.7L Cummins, the belt is readily accessible from above. Identify the belt tensioner, which is a spring-loaded pulley assembly that maintains belt tension.
2. 2

   Relieve belt tension
   Locate the 3/8" or 1/2" square drive hole in the belt tensioner arm. Insert a breaker bar or serpentine belt tool into the tensioner and rotate the tensioner clockwise (toward the engine) to relieve tension on the belt. The tensioner spring will provide resistance.
3. 3

   Remove the old serpentine belt
   While holding tension on the tensioner with the breaker bar, slip the belt off one of the pulleys (typically the alternator or idler pulley is easiest). Slowly release the tensioner back to its rest position. Remove the belt from the remaining pulleys and extract it from the engine bay.
4. 4

   Inspect pulleys and tensioner
   With the belt removed, manually spin each pulley including the crankshaft, alternator, idler, and tensioner pulleys. Check for roughness, wobble, excessive play, or noise. Inspect the tensioner for smooth travel and proper spring tension. Replace any worn components before installing the new belt.
   Torque spec

   Belt Tensioner Bolt55 Nm (41 lb-ft)

   Idler Pulley Bolt45 Nm (33 lb-ft)
5. 5

   Route the new serpentine belt
   Begin routing the new belt following your reference photo or the diagram on the fan shroud. Start by placing the belt around the crankshaft pulley at the bottom, then work upward around each pulley in sequence. Leave one pulley (typically the alternator or idler) for last, ensuring smooth grooves are properly seated in each pulley.
6. 6

   Install belt onto final pulley
   Insert the breaker bar into the belt tensioner and rotate it clockwise to relieve tension. Route the belt over or under the final pulley (depending on routing), ensuring all ribs are properly seated in the pulley grooves. Slowly release the tensioner to apply proper tension to the belt.
7. 7

   Verify belt installation
   Visually inspect the entire belt route to confirm it matches the routing diagram and that all belt ribs are properly seated in each pulley groove. Check that the belt is not twisted and runs straight on each pulley. The belt should sit centered on all pulleys without overhanging edges.
8. 8

   Reconnect battery and test
   Reconnect the negative battery cable. Start the engine and observe the belt operation. Listen for any squealing, chirping, or unusual noises. Watch for proper belt tracking on all pulleys. Allow the engine to run for 1-2 minutes while monitoring belt performance, then shut off and re-inspect belt seating.

Reassembly

1. Ensure the new belt is properly seated in all pulley grooves before starting the engine
2. If tensioner or idler pulley was replaced, verify proper torque on mounting bolts per specifications
3. No further reassembly is required as this is a straightforward belt replacement

Verification

• Verify belt routing matches the factory diagram with proper rib engagement on all pulleys
• Start engine and confirm no belt noise (squealing or chirping) during operation
• Check that belt tracks centered on all pulleys without walking off to one side
• Inspect belt tension by pressing on the longest span - should have approximately 1/2 inch deflection with firm thumb pressure
• After initial test run, shut off engine and re-inspect belt seating on all pulleys

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