This procedure covers removal and replacement of the serpentine belt driving the alternator on the 3.5L EcoBoost engine.

Warnings

Tools required

Parts

• Serpentine belt (alternator/accessory belt) × 1 — Gates K060925 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely
3. Photograph or diagram the serpentine belt routing path from above the engine bay
4. Verify replacement belt matches OEM specifications for length and width

Procedure

1. 1

   Access the belt tensioner
   Open the hood and locate the automatic belt tensioner on the driver's side of the engine. The tensioner is spring-loaded and uses a 15mm hex center for rotation. Identify the belt routing around all pulleys including alternator, water pump, A/C compressor, crankshaft, and tensioner.
2. 2

   Release belt tension
   Insert a 3/8" ratchet or breaker bar into the 15mm square hole in the center of the tensioner arm. Rotate the tensioner clockwise (toward the passenger side) to release tension on the belt. The tensioner will move approximately 1-2 inches.
3. 3

   Remove old belt
   While holding tension released, slip the belt off the alternator pulley first, then allow the tensioner to slowly return to rest position. Remove the belt from remaining pulleys by pulling upward from the engine bay. Inspect the tensioner pulley for smooth rotation and no bearing noise or wobble.
4. 4

   Inspect pulleys and tensioner
   Examine all pulley surfaces for damage, glazing, or wear. Check the tensioner pulley bearing by spinning it by hand - it should rotate freely without grinding or excessive play. Inspect the alternator pulley for cracks or wobble. Replace any damaged components before installing new belt.
5. 5

   Route new belt
   Starting at the crankshaft pulley, route the new belt following your photo or diagram. Ensure ribbed side contacts all pulleys. Route around water pump, A/C compressor, and other accessories, leaving the alternator and tensioner for last. Verify the belt is seated in all pulley grooves properly, not riding on pulley edges.
6. 6

   Install belt on alternator
   Rotate the tensioner clockwise again with your ratchet or breaker bar. Slip the belt over the alternator pulley, then over the tensioner pulley. Carefully release the tensioner, allowing it to apply proper tension to the belt. The tensioner arm should rest in the normal operating position between the tension limit marks.
7. 7

   Verify installation
   Double-check that the belt is properly seated in all pulley grooves and follows the correct routing path. The belt should not twist anywhere along its path. Manually rotate the tensioner one more time to confirm smooth operation and verify the belt remains seated.

Reassembly

1. No disassembly was required for this procedure
2. Ensure all tools are removed from engine bay before starting engine

Verification

• Start the engine and listen for any squealing, chirping, or unusual noises from the belt area
• Observe the belt for proper tracking on all pulleys - it should not slip or walk off any pulley
• Run engine for 2-3 minutes and verify the alternator is charging (battery light should be off)
• After the first 50-100 miles, visually inspect belt tension and seating to ensure no issues have developed

More procedures for this vehicle