2024 International LT Serpentine Belt Routing & Part Numbers

As an ASE-certified master technician, I know that maintaining the accessory drive system on a heavy-duty rig like the 2024 International LT is critical to keeping you on the road and out of the breakdown lane. The 2024 International LT is primarily equipped with either the Cummins X15 or the new International S13 integrated powertrain. Because accessory drives in heavy-duty trucks vary significantly based on alternator setups (single vs. dual) and compressor configurations, the specifications below reflect the most common single-alternator standard accessory drive for the Cummins X15. Always verify with your VIN before purchasing parts.

Quick answer

For the standard Cummins X15 configuration on the 2024 International LT:

• Belt length: 82.0 to 82.5 inches (varies slightly by aftermarket manufacturer)
• Rib count: 8-rib
• OEM belt PN: Cummins 3103233 (Navistar equivalent varies by spec)
• Aftermarket cross-refs: Gates K080820HD (FleetRunner Heavy Duty), Dayco 5080820HD, Continental Elite 4080820
• Auto-tensioner PN: Cummins 3691280 (Aftermarket: Dayco 89436)
• Idler pulley PN: Cummins 3687223 (Aftermarket: Gates 38024)

Note: If your LT has the International S13 engine or a dual-alternator/high-output setup, your belt length, rib count, and routing will differ. Always check your door jamb VIN against the parts catalog.

Belt routing

Heavy-duty engine bays have plenty of room, but stringing a thick 8-rib or 10-rib belt correctly is still a challenge if you lose track of the path. Before removing the old belt, take a clear photograph of the existing routing with your smartphone. Many International LT hoods also have a routing diagram sticker on the underside of the hood or near the radiator support.

For the standard single-belt X15 routing, the path generally follows this order:

1. Start by wrapping the belt around the bottom of the crankshaft pulley (grooved side against the pulley).
2. Bring the belt up and around the A/C compressor (grooved side against the pulley).
3. Route the belt down and under the idler pulley (smooth side against the pulley).
4. Pull the belt up and over the alternator (grooved side against the pulley).
5. Route it down around the water pump (grooved side against the pulley).
6. Finally, slip the belt behind the auto-tensioner pulley (smooth side against the pulley), leaving just enough slack to slide it fully onto the tensioner when you relieve the spring pressure.

How to replace the serpentine belt

Replacing the belt on an International LT requires basic hand tools, but due to the heavy spring rate of a heavy-duty tensioner, extreme caution is required.

1. Locate the tensioner: On the X15, the tensioner is typically located on the passenger side of the front accessory drive.
2. Release the tension: Insert a long 1/2-inch drive breaker bar (or a specialized heavy-duty serpentine belt tool) into the square drive hole on the tensioner arm.
3. Remove the belt: Rotate the tensioner arm to release the belt tension. Carefully slip the belt off the easiest accessible pulley (usually the alternator or water pump). Slowly release the tensioner back to its resting position—do not let it snap back, as this can damage the internal spring.
4. Inspect the pulleys: Spin the idler, alternator, and A/C compressor pulleys by hand. Listen for grinding bearings and check for wobble. Inspect the tensioner for cracks or fluid leaks.
5. Install the new belt: Route the new belt following your reference photo or the text path above. Leave the tensioner pulley for last.
6. Apply tension: Crank the tensioner open with your breaker bar, slip the belt over the final pulley, and slowly release the tensioner to apply pressure. Double-check that all ribs are seated perfectly in the grooves of every ribbed pulley before starting the truck.

Replacement interval

For line-haul trucks like the 2024 International LT, preventive maintenance is everything.

• Serpentine Belt: Replace every 100,000 to 150,000 miles, or every two years, whichever comes first. Heavy-duty EPDM belts often do not show traditional cracking; instead, they lose material in the rib valleys. Use a belt wear gauge to check groove depth.
• Tensioner and Idler Pulleys: It is highly recommended by ASE standards to replace the belt tensioner and idler pulley at the same time as the belt. A worn tensioner is the number one cause of premature belt failure.

Signs of a failing belt or tensioner

Don't ignore the warning signs of accessory drive failure:

• Squealing or chirping: Often heard on startup or when the A/C compressor engages. This indicates belt slip, usually caused by a weak tensioner spring or a stretched belt.
• Loss of power steering or alternator output: If the belt slips badly enough, your alternator won't charge properly (triggering a battery light) and the steering can become heavy.
• Tensioner "chatter": With the engine running, observe the tensioner arm. If it is bouncing aggressively, the internal dampener has failed and the tensioner must be replaced immediately.
• Visible wear: Frayed edges, missing rib sections, or a shiny, glazed appearance on the belt's ribbed side.

Find a trusted shop on Repairius.