2025 Ford F-150 — Serpentine Belt Routing, Length & Part Numbers

As an ASE-certified master technician, I’ve replaced countless drive belts on Ford trucks. The 2025 Ford F-150 continues the legacy of tough, capable trucks, but keeping it on the road requires staying on top of routine maintenance like the serpentine belt.

Because the 2025 F-150 is offered with multiple powertrains—including the 2.7L EcoBoost, 3.5L EcoBoost, 5.0L V8, and the 3.5L PowerBoost Hybrid—part numbers and routing can vary significantly. For this guide, we are focusing on the highly popular 3.5L EcoBoost V6. Always verify your specific engine displacement and sub-model before purchasing parts.

Quick answer: 3.5L EcoBoost Specs

Here are the essential part numbers and specifications you need for the 2025 Ford F-150 3.5L EcoBoost drive belt system:

• Rib count: 6-rib
• Belt length: 64.0 inches (varies slightly by aftermarket brand)
• OEM Belt Part Number: Motorcraft JK6-1049 (Verify with VIN)
• Aftermarket Cross-References: Gates K060640, Dayco 5060640, Continental 4060640
• Auto-Tensioner Part Number: Motorcraft BT-115 (or equivalent)
• Idler Pulley Part Number: Motorcraft YS-385 (or equivalent)

Note: Modern F-150s utilize Electronic Power Assist Steering (EPAS). You will not find a power steering pump on this routing diagram!

Belt routing

Because we cannot physically show you a diagram right now, it is critical that you photograph your existing belt before removal. A quick picture on your smartphone can save you an hour of frustration later.

For the 3.5L EcoBoost, the standard 6-rib belt routes as follows (starting from the bottom and moving clockwise):

1. Start by looping the belt around the bottom of the Crankshaft Pulley.
2. Bring the belt up and over the smooth Water Pump Pulley.
3. Route it down and around the grooved Alternator Pulley.
4. Pull the belt up and over the smooth Idler Pulley.
5. Route it down around the grooved A/C Compressor Pulley.
6. Finally, slip the backside (smooth side) of the belt under the Auto-Tensioner Pulley to complete the loop back to the Crankshaft.

How to replace the serpentine belt

Replacing the serpentine belt on a 2025 F-150 is straightforward but requires working in a tight engine bay.

Tools needed:

• Serpentine belt tool or a long 3/8" drive breaker bar
• Safety glasses and gloves

Step-by-step:

1. Locate the auto-tensioner on the passenger side of the engine block.
2. Insert your 3/8" breaker bar or serpentine belt tool into the square receptacle on the tensioner arm.
3. Rotate the tensioner counter-clockwise (away from the belt) to relieve the tension.
4. Slip the old belt off the closest, easiest pulley (usually the idler pulley or alternator).
5. Carefully release the tensioner and remove the tool. Unthread the old belt from the engine bay.
6. Route the new belt following your reference photo and the path described above. Leave the easiest pulley for last.
7. Rotate the tensioner again, slip the new belt onto the final pulley, and slowly release the tensioner to lock it into place.
8. Double-check every pulley to ensure the ribs of the belt are perfectly seated in the grooves.

Replacement interval

For the 2025 Ford F-150, Ford generally recommends inspecting the serpentine belt at 60,000 miles and replacing it every 100,000 miles. However, I always advise my customers to replace the belt, tensioner, and idler pulley together between 75,000 and 90,000 miles. Replacing the pulleys at the same time as the belt prevents premature wear on your brand-new belt.

Signs of a failing belt or tensioner

Don't wait for a breakdown to replace your drive belt. Look out for these warning signs:

• Squealing or chirping noises: Especially on startup or when the A/C compressor engages. This indicates a loose belt or a weak tensioner spring.
• Visible wear: Look for cracking, fraying, missing ribs, or a glazed/shiny appearance on the belt material.
• Accessory failure: If the battery light comes on (alternator not charging) or the A/C stops blowing cold, the belt may have slipped or snapped.
• Pulley wobble: If you see the tensioner bouncing excessively while the engine is running, the tensioner shock/spring is worn out.

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