Harmonic Balancer

This procedure covers the removal and replacement of the harmonic balancer on the 5.9L Cummins diesel engine, including removal of necessary accessories and proper installation torque procedures.

Warnings

Tools required

Parts

• Harmonic balancer × 1 — Use OEM specification
• Harmonic balancer bolt (if TTY) × 1 — Use OEM specification
• Front cover gasket (if damaged) × 1 — Use OEM specification
• Shop towels × 1 — Generic

Preparation

1. Ensure engine is completely cool
2. Disconnect both battery cables, negative first
3. Raise and support front of vehicle on jack stands
4. Remove passenger side front wheel for better access (4WD models)
5. Remove engine skid plate if equipped
6. Position drain pan under work area for potential coolant/oil drips

Procedure

1. 1

   Remove serpentine belt and accessories
   Rotate the serpentine belt tensioner clockwise and remove the belt from all pulleys. If access is limited, you may need to remove the upper radiator hose and fan shroud. On some models, the cooling fan assembly must be removed for clearance.
2. 2

   Remove crankshaft pulley
   The crankshaft pulley is mounted to the harmonic balancer with several bolts (verify count against FSM). Remove these mounting bolts and pull the pulley off the balancer. Remove these mounting bolts and pull the pulley off the balancer. Clean any debris or rust from the pulley face.
   Torque spec

   Sensor Mounting Bolts11 Nm (8 lb-ft)
3. 3

   Lock crankshaft rotation
   The crankshaft must be prevented from rotating to remove the harmonic balancer bolt. Install a flywheel holding tool through the bellhousing inspection cover, or use a large pry bar wedged against the flywheel ring gear and a bellhousing bolt. Ensure the transmission is in gear (manual) or in Park (automatic) to help resist rotation, but rely primarily on the flywheel holding tool.
   ⚠Do not use excessive force on flywheel teeth that could cause damage. Support pry bar properly to avoid slipping.
4. 4

   Remove harmonic balancer center bolt
   Using a 1-1/8 inch (or 28mm) socket on a breaker bar or impact wrench, remove the harmonic balancer center bolt by turning counterclockwise. This bolt is torqued to the FSM specification (verify — Cummins 5.9L typically requires an initial torque followed by an angular turn) and may be very tight. An impact wrench is highly recommended. Remove the bolt and washer completely.
   ℹ️This bolt is likely torque-to-yield and should be replaced. Consult service manual to verify before reusing.
5. 5

   Remove harmonic balancer
   Install a proper 3-jaw harmonic balancer puller onto the balancer. The puller bolt should thread into the crankshaft center bolt hole. Tighten the puller center bolt gradually and evenly while supporting the balancer to prevent it from falling. Continue tightening until the balancer releases from the crankshaft. Remove the balancer and puller.
   ⚠️Never use a jaw-type puller that grips the outer ring of the balancer. This will separate the rubber ring from the hub and destroy the balancer.
6. 6

   Inspect crankshaft and timing cover
   Inspect the crankshaft snout for any scoring, burrs, or damage. Clean the crankshaft snout and keyway thoroughly with brake cleaner and a wire brush. Inspect the front timing cover for oil leaks around the seal area. Check the woodruff key in the crankshaft keyway - it should be tight and undamaged. If loose or damaged, it must be replaced.
   ℹ️If front cover seal is leaking, this is an ideal time to replace it while the balancer is removed.
7. 7

   Inspect new harmonic balancer
   Verify the new harmonic balancer matches the old unit exactly. Check that the keyway slot is clean and free of burrs. Inspect the rubber ring for any damage or separation from shipping. Apply a thin coat of clean engine oil to the crankshaft snout and balancer bore.
8. 8

   Install harmonic balancer
   Align the keyway in the harmonic balancer with the woodruff key on the crankshaft. Slide the balancer onto the crankshaft snout as far as it will go by hand. Install the harmonic balancer installation tool (threaded rod with thrust bearing and plate) and carefully draw the balancer onto the crankshaft until it is fully seated. The balancer is properly installed when it is fully seated against the crankshaft shoulder; do not rely on it being flush with the end of the crankshaft. Remove the installation tool.
   ⚠️Never hammer or drive the balancer onto the crankshaft. This will damage the crankshaft thrust bearing and may crack the balancer.
9. 9

   Install harmonic balancer center bolt
   Clean the harmonic balancer bolt threads. Follow the FSM for thread preparation (the Cummins damper bolt is typically installed clean or lightly oiled and tightened with a torque-plus-angle procedure rather than using thread locker). If replacing with a new bolt, use as supplied. Install the bolt with washer and hand-tighten. Lock the crankshaft using the same method as removal. Final tightening must be performed with a torque wrench (and angle gauge if an angular spec applies); do not use an impact wrench for final tightening.
   ⚠Verify whether bolt is torque-to-yield. Some applications require angular torque after initial torque. An impact wrench is acceptable for final tightening if torque wrench range is insufficient.
10. 10

    Install crankshaft pulley
    Position the crankshaft pulley onto the harmonic balancer, aligning all bolt holes. Install the pulley mounting bolts and tighten in a crossing pattern.
    Torque spec

    Sensor Mounting Bolts11 Nm (8 lb-ft)
11. 11

    Reinstall accessories and serpentine belt
    Reinstall any components removed for access (fan assembly, fan shroud, radiator hose if removed). Route the serpentine belt around all pulleys in the correct pattern. Rotate the tensioner clockwise and slip the belt onto the final pulley. Verify belt is properly seated in all pulley grooves.

Reassembly

1. Reinstall engine skid plate and torque fasteners to specification
2. Reinstall passenger side front wheel (4WD) and torque lug nuts to 135 ft-lbs
3. Reconnect battery cables, positive first then negative
4. Lower vehicle from jack stands

Verification

• Start engine and verify no unusual vibrations or noises from front of engine
• Check for oil leaks around front timing cover seal area
• Verify serpentine belt is tracking properly on all pulleys and not slipping
• Observe harmonic balancer during idle - it should run smooth without wobble
• Rev engine slightly and verify smooth operation throughout RPM range
• Test drive vehicle and verify no vibrations at various speeds

More procedures for this vehicle