This procedure covers removal and replacement of the harmonic balancer (crankshaft damper) on the 3.5L EcoBoost V6 engine, including accessory drive belt removal and front cover access.

Warnings

Tools required

Parts

• Harmonic balancer/crankshaft damper × 1 — Motorcraft DG-527 or equivalent
• Harmonic balancer bolt (TTY) × 1 — Use OEM specification
• Front cover gasket × 1 — Use OEM specification if damaged
• Engine coolant × 1 — Motorcraft Orange Coolant

Fluids

• Motorcraft Orange Coolant — 2 qt

Preparation

1. Ensure engine is completely cool to the touch
2. Disconnect negative battery cable and secure away from terminal
3. Raise vehicle and support securely on jack stands at manufacturer-specified lift points
4. Remove engine splash shield/under-cover to access lower engine components
5. Place drain pan beneath radiator and drain approximately 2 quarts of coolant from petcock or lower radiator hose
6. Remove driver-side wheel for improved access to lower engine area (optional but recommended)

Procedure

1. 1

   Remove accessory drive belt
   Locate the spring-loaded belt tensioner on the front of the engine. Using a 3/8" ratchet or belt tension tool, rotate the tensioner clockwise to release tension. Slide the serpentine belt off the pulleys and slowly release tensioner. Remove belt from engine bay and inspect for wear.
2. 2

   Remove crankshaft position sensor
   Locate the crankshaft position (CKP) sensor on the lower left side of the engine block near the harmonic balancer. Disconnect the electrical connector by pressing the release tab. Remove the sensor mounting bolt and carefully extract the sensor from the block. Keep sensor clean and protected.
   Torque spec

   Sensor Bolts12 Nm (9 lb-ft)
3. 3

   Remove power steering pump (if equipped with hydraulic)
   Note: Most 2015-2020 F-150s have electric power steering. If your vehicle has a hydraulic pump mounted low on the driver side, unbolt the pump mounting bolts and secure the pump aside without disconnecting hoses. If electric steering, skip this step.
4. 4

   Access and remove harmonic balancer bolt
   The crankshaft must be prevented from rotating. Use a crankshaft holding tool inserted into the flywheel/flexplate teeth from below, or use a strap wrench on the balancer itself. Using a breaker bar or impact wrench, remove the center harmonic balancer bolt by turning counterclockwise. This bolt requires significant force and is often installed with thread locker.
   ⚠️Do not attempt to hold the crankshaft by jamming a screwdriver in the ring gear. This can damage the flexplate or flywheel.
   Torque spec

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

   Mark and remove harmonic balancer
   Before removal, use a paint pen or marker to mark the rotational position of the balancer relative to the crankshaft snout. Install a proper 3-jaw harmonic balancer puller that grips behind the inner hub (NOT the outer ring). Thread the puller center bolt into the crankshaft threads and tighten gradually, alternating pressure evenly until the balancer releases from the crankshaft. Remove puller and balancer.
   ⚠️Using an improper puller or pulling on the outer damper ring will destroy the harmonic balancer's rubber isolation and require replacement.
6. 6

   Inspect crankshaft snout and keyway
   Examine the crankshaft snout for scoring, damage, or excessive wear. Inspect the Woodruff key (half-moon shaped key) in the crankshaft keyway - it should be intact and seated properly. Check for any oil leaks from the front crankshaft seal. If seal is leaking, this is the opportunity to replace it. Clean the crankshaft snout thoroughly with brake cleaner and a lint-free cloth.
7. 7

   Prepare new harmonic balancer
   Inspect the new harmonic balancer keyway slot for burrs or sharp edges. Verify the balancer matches the old unit in dimensions and keyway orientation. Apply a thin coat of clean engine oil to the crankshaft snout and the inner bore of the new balancer. Do NOT use grease or assembly lube.
8. 8

   Install harmonic balancer
   Align the keyway slot in the harmonic balancer with the Woodruff key on the crankshaft. Slide the balancer onto the snout by hand as far as possible, ensuring proper key alignment. Using a harmonic balancer installation tool (threaded installer that threads into the crank and uses a thrust bearing to press the balancer), slowly draw the balancer onto the crankshaft until it is fully seated. The balancer should seat flush against the crankshaft timing gear. Do NOT hammer the balancer into place.
   ⚠Never install a harmonic balancer by hammering or impact. This damages the internal damper mechanism and can cause catastrophic failure.
9. 9

   Install new harmonic balancer bolt
   Apply medium-strength thread locker to the threads of the NEW harmonic balancer bolt (TTY bolt - never reuse). Install the bolt by hand, then use the crankshaft holding tool to prevent rotation. Torque the bolt to 180 Nm (133 lb-ft) using a calibrated torque wrench. Verify the torque specification in the factory service manual as some model years may require additional angle torque (e.g., 180 Nm plus 90 degrees).
   ⚠️This is a critical torque-to-yield fastener. Failure to replace or properly torque this bolt can result in the harmonic balancer coming loose during operation, causing catastrophic engine damage.
   Torque spec

   Harmonic Balancer Bolt180 Nm (133 lb-ft)
10. 10

    Reinstall crankshaft position sensor
    Clean the CKP sensor mounting hole and sensor tip with brake cleaner. Inspect the O-ring on the sensor and replace if damaged. Insert the sensor into the block, ensuring it seats fully. Install and torque the sensor bolt to specification. Reconnect the electrical connector until it clicks into place.
    Torque spec

    Sensor Bolts12 Nm (9 lb-ft)
11. 11

    Reinstall accessory drive belt
    Route the serpentine belt around all pulleys according to the belt routing diagram (typically found on a decal under the hood or in the owner's manual). Rotate the belt tensioner clockwise and slip the belt onto the final pulley. Slowly release the tensioner. Verify the belt is properly seated in all pulley grooves and is not twisted.
12. 12

    Refill coolant and check for leaks
    Refill the cooling system with Motorcraft Orange Coolant to the proper level. Close the radiator petcock or reconnect the lower hose. Start the engine and allow it to reach operating temperature while monitoring for leaks around the front cover area. Check coolant level again after engine reaches temperature and top off as needed. Burp the cooling system per manufacturer procedure.

Reassembly

1. Reinstall engine splash shield/under-cover and torque fasteners to specification
2. Reinstall driver-side wheel if removed and torque lug nuts to 150 lb-ft in a star pattern
3. Lower vehicle from jack stands
4. Reconnect negative battery cable

Verification

• Start engine and listen for unusual vibrations or noises from the front of the engine - a properly installed harmonic balancer should run smoothly
• Check for proper accessory belt operation with no squealing or slipping
• Verify no check engine light for crankshaft position sensor codes (P0335, P0336)
• Monitor for coolant leaks during initial test drive
• Perform a brief test drive and verify smooth engine operation at all RPM ranges
• After 50-100 miles, re-check the harmonic balancer bolt torque with engine cool to ensure it has not loosened

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