Serpentine Belt

This procedure covers the removal and replacement of the serpentine belt on the 3.5L V6 EcoBoost engine, including tensioner release and belt routing verification.

Warnings

Tools required

Parts

• Serpentine belt × 1 — Use OEM Ford or quality aftermarket (approx. 2400mm length)

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely if recently operated
3. Open hood and secure with prop rod
4. Photograph the serpentine belt routing from multiple angles for reference during installation

Procedure

1. 1

   Locate belt tensioner and routing
   From the front of the vehicle, identify the automatic belt tensioner located on the passenger side of the engine. Note the belt routing around the crankshaft pulley, water pump, alternator, A/C compressor, idler pulley, and tensioner pulley. The tensioner has a 3/8" square drive socket for a ratchet or a 15mm hex head.
2. 2

   Release belt tension
   Insert a 3/8" drive ratchet or breaker bar into the square drive hole on the belt tensioner arm. Rotate the tensioner clockwise (toward the passenger side) to release tension on the belt. The tensioner will move approximately 45-60 degrees. Maintain steady pressure to keep tensioner compressed.
3. 3

   Remove serpentine belt
   While holding the tensioner in the released position, slip the serpentine belt off the nearest pulley (typically the alternator or tensioner pulley itself). Once the belt is free from one pulley, slowly release the tensioner to return to its resting position. Remove the belt from the remaining pulleys and extract it from the engine bay.
4. 4

   Inspect pulleys and tensioner
   With the belt removed, visually inspect all pulleys for damage, rough bearings, or excessive wear. Spin each pulley by hand to check for noise, roughness, or wobble. Check the tensioner arm for smooth operation and verify the tensioner pulley spins freely. If any components show wear or damage, they should be replaced now.
5. 5

   Route new serpentine belt
   Beginning at the crankshaft pulley, route the new serpentine belt around all pulleys EXCEPT the tensioner pulley, following your reference photos or the belt routing diagram (typically found on the radiator support or under-hood label). Ensure the belt is properly seated in all pulley grooves. The ribbed side of the belt contacts all pulleys except the idler pulley(s), where the smooth back may contact depending on routing.
6. 6

   Install belt onto tensioner pulley
   Using your 3/8" ratchet or breaker bar, again rotate the belt tensioner clockwise to compress it. Position the belt over the tensioner pulley, ensuring it is properly seated in the pulley grooves. Slowly release the tensioner, allowing it to apply proper tension to the belt. Verify the tensioner moves smoothly and returns to its operating position.
7. 7

   Verify belt installation
   Visually confirm the belt is properly seated in all pulley grooves along its entire length. Check that the belt does not contact any engine covers, brackets, or other components. Manually rotate the crankshaft pulley two complete revolutions clockwise (using a socket on the crankshaft bolt) and watch the belt track properly on all pulleys without slipping or misalignment.

Reassembly

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

Verification

• Start the engine and listen for any squealing, chirping, or unusual noises from the belt area
• Observe the belt operation at idle - it should run smoothly without slipping or excessive vibration
• Rev the engine slightly and verify the belt remains properly seated on all pulleys
• Check for proper alternator charging (battery light should be off) and A/C compressor operation if equipped
• Re-inspect belt routing after 5-10 minutes of operation to ensure it has not shifted out of position

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