This procedure covers removal and replacement of the serpentine belt (alternator belt) on the 2015-2020 Ford F-150 with the 3.5L EcoBoost V6 engine.

Warnings

Tools required

Parts

• Serpentine belt × 1 — Gates K060980 or equivalent OEM Motorcraft

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow engine to cool completely if recently operated
3. Open hood and secure with prop rod
4. Locate the serpentine belt routing diagram on the radiator support or under hood; take a photo for reference if diagram is missing

Procedure

1. 1

   Inspect current belt condition
   Before removal, inspect the existing belt for wear patterns, cracks, glazing, or contamination. Check all pulleys for alignment and bearing noise by spinning them by hand. Document the belt routing path by comparing to the underhood diagram or taking a clear photograph showing how the belt wraps around each pulley.
2. 2

   Locate the belt tensioner
   The automatic belt tensioner is located on the driver's side of the engine block, below the alternator. It is a spring-loaded pulley assembly with a 3/8 inch square drive socket in the tensioner arm for tool engagement. Identify the tensioner rotation direction needed to relieve belt tension (clockwise rotation when viewed from front).
3. 3

   Release belt tension
   Insert a 3/8 inch drive ratchet or breaker bar into the square drive hole on the tensioner arm. Rotate the tensioner clockwise (toward the passenger side) to compress the spring and relieve tension on the belt. The tensioner will move approximately 1-2 inches. Maintain steady pressure; the spring is strong but should move smoothly.
4. 4

   Remove the serpentine belt
   While holding the tensioner in the released position, slip the belt off the nearest pulley (typically the alternator pulley or smooth idler pulley). Once the belt is free from one pulley, carefully release the tensioner and allow it to return to its rest position. Remove the belt from the remaining pulleys and extract it from the engine compartment, routing it past the cooling fan if necessary.
5. 5

   Inspect pulleys and tensioner
   With the belt removed, inspect all pulley surfaces for damage, grooving, or debris. Spin each pulley by hand to check for roughness or bearing noise. Inspect the tensioner pulley for wobble or lateral play. Check the tensioner arm movement by pressing on it; it should move smoothly with spring resistance and return to position without binding. Replace any damaged components before installing the new belt.
6. 6

   Route the new serpentine belt
   Starting at a pulley farthest from the tensioner, begin routing the new belt according to the diagram. Feed the belt around each pulley in sequence: crankshaft, water pump, power steering pump (if equipped), alternator, and idler pulleys. Leave the tensioner pulley for last. Ensure the ribbed side of the belt engages the grooved pulleys correctly and the smooth side contacts any flat pulleys. Double-check routing against your reference photo or diagram.
7. 7

   Install belt onto tensioner pulley
   Position the belt over the tensioner pulley groove but do not fully seat it yet. Insert your 3/8 inch drive tool into the tensioner arm and rotate it clockwise again to relieve tension. While holding the tensioner, guide the belt fully onto the tensioner pulley, ensuring it seats properly in the grooves. Slowly release the tensioner, allowing it to apply proper tension to the belt.
8. 8

   Verify belt installation
   Visually confirm the belt is properly seated in all pulley grooves with no twists or misalignment. Check that the belt ribs are fully engaged in each grooved pulley. Verify the belt routing matches the underhood diagram exactly. Manually rotate the crankshaft one full revolution using a wrench on the crankshaft bolt (clockwise only) to ensure the belt tracks properly and does not slip off any pulleys.

Reassembly

1. No disassembly was required for this procedure; reassembly steps are not applicable
2. Ensure no tools or materials are left in the engine compartment before closing the hood

Verification

• Start the engine and allow it to idle while observing belt operation through the engine bay from a safe distance
• Listen for any squealing, chirping, or unusual noises that could indicate misalignment or improper tension
• Visually confirm the belt runs smoothly on all pulleys without wobbling or jumping
• Verify all electrical systems (alternator charging, power steering assist) function normally
• After initial engine run, shut off and recheck belt alignment and seating on all pulleys
• Road test the vehicle and monitor for any belt-related noises or charging system warning lights

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