2019 International LT Serpentine Belt Replacement Guide

Quick Answer

• Engine Application: Cummins X15 (2017+)
• Belt Length: Varies by alternator option, but a common configuration uses a 2405mm belt (94.7 inches).
• Rib Count: 8-rib
• OEM Belt Part Number: Cummins 3691024
• Aftermarket Cross-References:
  • Gates K080947HD
  • Dayco 5080945
  • Continental 4080945
• Automatic Tensioner Part Number: Cummins 5262793, Gates 38642
• Idler Pulley Part Number: Cummins 3691372, Gates 36316 (Grooved), Gates 36149 (Smooth)

Belt Routing

Before you remove the old belt, always take a clear photograph of the belt's path with your phone. This will be your best guide. The routing can vary slightly based on the specific alternator and accessories fitted to your truck.

For most 2019 International LT models with the Cummins X15 engine, the belt follows this path:

1. Starts at the main crankshaft pulley at the bottom.
2. Wraps up and around the A/C compressor pulley.
3. Goes down to an idler pulley.
4. Travels up to the alternator pulley.
5. Comes across to the power steering pump.
6. Goes down and around the water pump.
7. Finishes by wrapping around the spring-loaded automatic tensioner before returning to the crank pulley.

How to Replace the Serpentine Belt

Replacing the serpentine belt on the X15 engine is straightforward with the right tool. You will need a serpentine belt tool or a long-handled 1/2-inch drive breaker bar or ratchet.

1. Safety First: Make sure the engine is off and cool, and the keys are out of the ignition.
2. Locate the Tensioner: The automatic tensioner has a 1/2" square hole in its body, designed for your tool.
3. Release Tension: Insert the square drive of your breaker bar or serpentine belt tool into the hole. Pivot the tensioner arm to release the tension on the belt. The arm is under strong spring pressure, so this will require significant force.
4. Remove Old Belt: While holding the tensioner, carefully slip the old belt off one of the smooth pulleys, like the water pump or an idler. Then, slowly release the tensioner and remove the belt entirely.
5. Install New Belt: Following your photo and the routing diagram described above, thread the new belt around all the pulleys, saving a smooth, easily accessible pulley for last.
6. Apply Tension: Using your tool, pivot the tensioner arm again and slide the belt over the final pulley. Double-check that the belt is centered in the grooves of every ribbed pulley and is riding correctly on all smooth pulleys.
7. Final Check: Slowly release the tensioner, ensuring it applies firm pressure to the belt. Do one last visual inspection of the entire belt path before starting the engine.

Replacement Interval

For a heavy-duty application like the International LT, the serpentine belt is a critical component. There is no strict mileage-based interval, but a thorough inspection should be part of every service.

• Inspect: Check the belt at every oil change (typically 25,000-50,000 miles, depending on your duty cycle) for cracks, glazing (shiny surface), fraying, or contamination from oil or coolant.
• Replace: As a general rule, plan to replace the belt every 100,000 to 150,000 miles, or immediately if you see any signs of wear. It is also wise to replace the tensioner and any idler pulleys at the same time, as their bearings wear out and can cause the new belt to fail prematurely.

Signs of a Failing Belt or Tensioner

Listen to your truck. It will often tell you when something is wrong. Be aware of these signs:

• Chirping or Squealing Noises: A constant high-pitched noise from the front of the engine is the most common sign of a worn or misaligned belt.
• Visible Wear: Cracks, missing ribs, or frayed edges on the belt mean it needs immediate replacement.
• Tensioner Vibration: With the engine running, watch the tensioner arm. If it is vibrating excessively or jumping around, the spring is likely weak and failing.
• Accessory Problems: Since the belt drives everything from the alternator to the water pump, a failing belt can cause a "Battery Not Charging" warning, power steering loss, or engine overheating.

If you notice any of these symptoms, address them promptly to avoid a breakdown on the road.

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