Harmonic Balancer

This procedure covers removal and installation of the harmonic balancer (crankshaft damper) on the 6.7L Cummins diesel engine, including accessory drive removal and proper torque sequence.

Warnings

Tools required

Parts

• Harmonic balancer/crankshaft damper × 1 — Use OEM specification
• Harmonic balancer bolt × 1 — TTY bolt - replace if specified
• Crankshaft front seal (recommended) × 1 — Use OEM specification
• Serpentine belt (inspect and replace if worn) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect both battery cables (negative first, then positive)
3. Raise and safely support front of vehicle on jack stands
4. Remove engine belly pan or skid plate if equipped
5. Allow engine to cool completely if recently operated
6. Take photo of serpentine belt routing for reference

Procedure

1. 1

   Remove serpentine belt and accessories
   Using serpentine belt tool, release belt tensioner and remove serpentine belt. Remove the cooling fan assembly by removing the mounting bolts securing the fan shroud and fan clutch assembly. On 6.7L Cummins, the fan may thread onto the water pump shaft - rotate counterclockwise (note reverse thread). Remove fan shroud if necessary for clearance.
   Torque spec

   Mounting Bolts37 Nm (27 lb-ft)
2. 2

   Remove accessory drive components
   Remove the crankshaft pulley if equipped as a separate component from the harmonic balancer. This may require removing multiple bolts. On this engine, the pulley typically mounts to the face of the harmonic balancer with separate bolts. Mark pulley orientation if necessary.
   Torque spec

   Crankshaft Pulley Bolt180 Nm (133 lb-ft)
3. 3

   Lock crankshaft from rotation
   Install flywheel holding tool through bellhousing access opening, or alternatively place transmission in gear (manual) or Park (automatic) and apply parking brake firmly. From underneath, verify crankshaft cannot rotate. This is critical for removing the harmonic balancer bolt.
4. 4

   Remove harmonic balancer center bolt
   Using a breaker bar or impact wrench, remove the harmonic balancer center bolt. This bolt is torqued to 133 lb-ft and may require significant force. If using a breaker bar, ensure crankshaft is locked. Impact wrench is preferred method. Remove bolt and washer completely. Inspect bolt threads and stretching - replace if TTY type or if elongation is visible.
   ⚠Sudden release of tension may occur. Ensure tools and hands are positioned safely.
   Torque spec

   Harmonic Balancer Bolt180 Nm (133 lb-ft)
5. 5

   Remove harmonic balancer
   Install harmonic balancer puller onto the balancer hub. Ensure puller bolts thread into the balancer properly and that the puller center screw contacts the crankshaft snout center (not threads). Tighten puller gradually and evenly to draw balancer off crankshaft. The balancer is pressed on with significant force. Never hammer or pry behind the balancer as this can damage the timing cover or crankshaft.
   ⚠️Improper removal technique can damage the crankshaft. Use only a proper harmonic balancer puller designed for this application.
6. 6

   Inspect components and crankshaft snout
   With balancer removed, inspect crankshaft snout for damage, scoring, or wear. Check the Woodruff key slot and key for wear or damage. Inspect front crankshaft seal for leakage. Inspect harmonic balancer inner bore for wear, cracking, or rubber separation. Replace balancer if rubber damping material shows deterioration or separation from inner/outer rings. Clean crankshaft snout thoroughly with solvent and lint-free cloth.
7. 7

   Replace front crankshaft seal (if applicable)
   If replacing the front crankshaft seal while balancer is removed, carefully pry out old seal from timing cover using seal puller or screwdriver. Clean seal bore in timing cover. Install new seal using seal driver to proper depth, ensuring seal is square and seated fully. Lubricate seal lip with clean engine oil before balancer installation.
8. 8

   Prepare harmonic balancer for installation
   Verify Woodruff key is properly seated in crankshaft keyway. Clean harmonic balancer inner bore with solvent and dry thoroughly. Apply a thin coat of clean engine oil to crankshaft snout and balancer bore. Align balancer keyway with Woodruff key on crankshaft.
9. 9

   Install harmonic balancer
   Using harmonic balancer installation tool, press balancer onto crankshaft snout until fully seated against crankshaft timing gear or inner step. The balancer must be pressed on using installation tool - never drive it on with hammer. Ensure balancer is fully seated and sits flush. Check that balancer does not wobble or sit crooked on crankshaft.
   ⚠️Hammering the balancer onto the crankshaft can cause internal engine damage. Use only a proper installation tool.
10. 10

    Install harmonic balancer center bolt
    Clean harmonic balancer bolt threads and crankshaft threads. Apply medium-strength thread locker to bolt threads if specified. Install washer and bolt. With crankshaft still locked, torque harmonic balancer bolt to 180 Nm (133 lb-ft). If bolt is TTY type and service manual specifies additional angle rotation, perform additional tightening as specified. Verify balancer does not wobble after bolt is torqued.
    ℹ️Verify with service manual if additional angle tightening is required beyond initial torque specification.
    Torque spec

    Harmonic Balancer Bolt180 Nm (133 lb-ft)
11. 11

    Reinstall crankshaft pulley
    Align crankshaft pulley to harmonic balancer using alignment marks or key. Install pulley mounting bolts and torque to specification. Ensure pulley is seated flush against balancer face.
    Torque spec

    Crankshaft Pulley Bolt180 Nm (133 lb-ft)
12. 12

    Reinstall accessories and serpentine belt
    Reinstall cooling fan assembly and fan shroud. If fan threads onto water pump, remember reverse thread (clockwise to tighten). Torque mounting bolts to specification. Route serpentine belt according to routing diagram (reference photo taken during disassembly). Use belt tensioner tool to install belt onto all pulleys. Verify belt is properly seated in all pulley grooves.
    Torque spec

    Mounting Bolts37 Nm (27 lb-ft)

Reassembly

1. Remove crankshaft locking tool if used
2. Reinstall engine belly pan or skid plate with appropriate fasteners
3. Lower vehicle from jack stands
4. Reconnect battery cables (positive first, then negative)
5. Verify all tools and parts have been removed from engine compartment

Verification

• Start engine and verify no unusual vibration or wobble from crankshaft pulley area
• Check for proper serpentine belt operation and verify belt stays on all pulleys
• Listen for abnormal noises from front of engine during idle and light throttle
• Inspect harmonic balancer area for any oil leakage from crankshaft seal
• Rev engine slightly and verify smooth operation without vibration
• After initial test run, re-check harmonic balancer bolt torque after engine cools

More procedures for this vehicle