2014 Kenworth T680 Serpentine Belt Guide

Quick Answer

For the 2014 Kenworth T680, serpentine belt specifications can vary depending on the engine. The most common engine options include the PACCAR MX-13 and Cummins ISX15. Always verify parts based on your specific engine and VIN.

• Belt Length (PACCAR MX-13): Approximately 2650mm – 2750mm (104–108 inches) depending on accessories.
• Rib Count: 8-rib (common for heavy-duty applications)
• OEM Belt PN (PACCAR MX-13, common): 1934988 (PACCAR)
• Aftermarket Cross-references (PACCAR MX-13):
  • Gates: K081065 / K081068 (Always verify length)
  • Dayco: 5081065 / 5081068
  • Continental Elite: 4081065 / 4081068
• Auto-Tensioner PN (PACCAR MX-13, common): 1978252 (PACCAR)
• Idler Pulley PN (PACCAR MX-13, common): 1978254 (PACCAR)

Belt Routing

The serpentine belt on your 2014 Kenworth T680 snakes around multiple pulleys to drive essential accessories. Before you begin any work, take a clear photograph of the existing belt routing. This will serve as an invaluable reference during reinstallation.

For most PACCAR MX-13 engine configurations, the routing generally follows this path:

1. Starting from the Crankshaft Pulley (the largest pulley at the bottom, typically driving the belt).
2. The belt will likely go up and over the A/C Compressor Pulley.
3. From the A/C compressor, it will typically route to an Idler Pulley, which helps guide the belt.
4. Next, the belt wraps around the Alternator Pulley, often located higher up in the engine bay.
5. From the alternator, it may go to the Power Steering Pump Pulley.
6. The belt then travels to the Water Pump Pulley, which is crucial for engine cooling.
7. Finally, the belt will route around the Auto-Tensioner Pulley, which maintains proper belt tension. The tensioner will have a square drive hole for a serpentine belt tool or a breaker bar to release tension.

Note: Specific configurations can vary based on optional equipment. Always refer to the under-hood diagram or your photographic reference.

How to Replace the Serpentine Belt

Replacing the serpentine belt on a 2014 Kenworth T680 requires basic mechanical aptitude and the right tools. Ensure the engine is cool before starting.

1. Safety First: Disconnect the negative battery terminal to prevent accidental starts.
2. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square drive hole (often 3/8" or 1/2") or a hex head for a wrench.
3. Release Tension: Insert a serpentine belt tool or appropriately sized breaker bar into the tensioner's square drive hole. Apply clockwise or counter-clockwise pressure (depending on the tensioner design) to rotate the tensioner arm and release tension on the belt. Hold the tensioner in this position.
4. Remove Old Belt: While holding the tensioner open, carefully slip the old belt off one of the pulleys (usually one of the idler pulleys or the alternator is easiest).
5. Inspect Pulleys: With the belt off, take this opportunity to manually spin each pulley (alternator, power steering pump, idlers, A/C compressor). Listen for grinding noises or feel for excessive play, which could indicate a failing bearing. Check for any cracks or damage on the pulleys.
6. Route New Belt: Following your photograph or the under-hood routing diagram, carefully route the new serpentine belt around all the pulleys, leaving the last pulley (e.g., an idler or the smooth side of a water pump pulley) for last. Ensure the ribs of the belt are properly seated in the grooved pulleys.
7. Final Tensioning: Once the belt is mostly routed, again apply pressure to the tensioner with your tool. Slip the belt over the final pulley. Slowly release the tensioner, ensuring the belt remains properly seated on all pulleys.
8. Double Check: Inspect the entire belt routing one last time to ensure it is correctly aligned on all pulleys and that the tensioner is applying proper pressure.
9. Reconnect Battery: Reconnect the negative battery terminal.
10. Test: Start the engine and listen for any abnormal noises or squealing. Observe the belt's operation for a few minutes.

Replacement Interval

For heavy-duty trucks like the Kenworth T680, routine inspection is key. Serpentine belts typically have a recommended replacement interval of 150,000 to 200,000 miles or approximately 4-5 years, whichever comes first. However, severe operating conditions (extreme temperatures, dusty environments, high engine hours) may necessitate earlier replacement. Always consult your truck's owner's manual for specific recommendations.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to a breakdown as essential accessories will stop functioning. Watch for these warning signs:

• Squealing or Chirping Noises: This is the most common symptom. A loud squeal, especially during cold starts, acceleration, or when wet, often indicates a worn belt or a misaligned/failing tensioner/pulley.
• Cracks, Fraying, or Glazing on the Belt: Visually inspect the belt. Deep cracks running across the ribs, fraying edges, or a shiny, glazed appearance on the belt's surface are all signs of wear and impending failure.
• Loss of Power to Accessories: If the belt is slipping or broken, you may notice the A/C not blowing cold, the power steering becoming difficult to turn, or the battery light illuminating (due to the alternator not charging).
• Wobbling Tensioner Pulley: With the engine running (safely observe from a distance, or with the engine off by trying to wiggle the pulley), a wobbling or vibrating tensioner pulley indicates a failing bearing.
• Belt Slipping off Pulleys: An extremely loose belt, often due to a failed tensioner, may slip off one or more pulleys.
• Growling or Grinding from Pulleys: This often points to a failing bearing within an idler pulley, the tensioner pulley, or an accessory (alternator, A/C compressor, power steering pump).

If you notice any of these symptoms, it's crucial to inspect and replace the faulty component promptly to avoid unexpected breakdowns.

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