2021 Ford Ranger Serpentine Belt Routing, Length & Part Numbers

As an ASE-certified master technician, I’ve seen my fair share of worn belts and stranded drivers. When it comes to the 2021 Ford Ranger equipped with the 2.3L EcoBoost 4-cylinder engine, staying on top of your accessory drive system is critical for keeping your truck on the road. A snapped belt will instantly kill your alternator, water pump, and air conditioning.

Whether you are performing routine maintenance or dealing with a squealing tensioner, this reference guide provides all the specifications, part numbers, and step-by-step routing instructions you need to tackle the job confidently.

Quick answer

Here are the essential specifications and verified part numbers for the 2021 Ford Ranger (2.3L EcoBoost):

• Rib Count: 6-rib belt
• Belt Length: Approximately 40.7 inches (1034 mm)
• OEM Belt Part Number: Motorcraft JK6-407 (or LB5Z-8620-A)
• Aftermarket Belt Cross-References: Gates K060407, Continental Elite 4060407, Dayco 5060408
• Auto-Tensioner Part Number: Motorcraft BT-132 (OEM) / Gates 39420
• Idler Pulley Part Number: Motorcraft YS-385 (OEM)

Note: The 2021 Ford Ranger uses Electronic Power Assist Steering (EPAS), meaning there is no traditional power steering pump driven by the serpentine belt.

Belt routing

Since we cannot render an image here, understanding the text-based routing path is crucial. Always photograph your existing belt routing before removing it—it’s the easiest way to save yourself a headache if you lose your place.

For the 2.3L EcoBoost engine, the ribbed side of the belt will ride on the grooved pulleys, while the smooth back side of the belt will ride on the smooth idler and tensioner pulleys.

Follow this routing path:

1. Start by looping the belt around the bottom of the Crankshaft Pulley.
2. Route it up and around the outside of the A/C Compressor.
3. Take the belt from the A/C compressor and run the smooth backside under the Idler Pulley.
4. Pull the belt up and over the top of the Alternator.
5. Route it down and around the Water Pump.
6. Finally, slip the smooth backside of the belt over the Auto-Tensioner Pulley before it connects back down to the crankshaft.

How to replace the serpentine belt

Replacing the serpentine belt on the 2021 Ranger is a straightforward job if you have the right tools. You will need a dedicated serpentine belt tool or a long 3/8" drive breaker bar.

1. Locate the tensioner: The automatic belt tensioner is located on the front of the engine block.
2. Relieve tension: Insert your 3/8" breaker bar or serpentine belt tool into the square receptacle on the tensioner arm. Rotate the tensioner counterclockwise (away from the belt) to relieve the spring tension.
3. Remove the old belt: While holding the tensioner open, slip the old belt off the easiest-to-reach smooth pulley (usually the idler or the water pump). Slowly release the tensioner and remove the belt from the engine bay.
4. Route the new belt: Follow the routing instructions above. Loop the belt around all pulleys except for the final smooth idler or tensioner pulley.
5. Install the final loop: Compress the tensioner again using your breaker bar, slip the new belt onto the final pulley, and carefully release the tensioner.
6. Verify seating: Double-check every single ribbed pulley to ensure the belt is perfectly seated within the grooves. An off-center belt will shred within seconds of starting the engine.

Replacement interval

For the 2021 Ford Ranger, the serpentine belt is made of durable EPDM rubber, which lasts much longer than older neoprene belts. However, EPDM belts wear like tire tread rather than cracking.

• Inspection interval: Inspect the belt and tensioner every 30,000 miles.
• Replacement interval: Standard replacement is recommended between 60,000 and 90,000 miles, or about every 5 to 7 years, whichever comes first.

Signs of a failing belt or tensioner

Don't wait for the belt to snap on the highway. Look and listen for these warning signs:

• Squealing or chirping: A high-pitched chirp on startup or during acceleration usually indicates a worn belt or a weak tensioner spring.
• Visible wear: While EPDM belts don't crack often, look for frayed edges, missing chunks of ribs, or a shiny, glazed appearance on the smooth side.
• Tensioner movement: With the engine idling, watch the auto-tensioner. A slight vibration is normal, but excessive bouncing indicates the internal dampener has failed.
• Accessory issues: Intermittent power drops from the alternator, lack of A/C cooling, or engine overheating can be caused by a slipping belt.

If you don’t have the time, tools, or confidence to tackle this job yourself, don't put it off. Find a trusted shop on Repairius.