2016 Kenworth T680 Serpentine Belt Guide

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Quick Answer: 2016 T680 Serpentine Belt Specifications (PACCAR MX-13 Engine)

Note: The following part numbers are for the common PACCAR MX-13 engine. Always verify part numbers with your truck's VIN before ordering.

• Belt Length: Approximately 2410mm (94.9 inches)
• Rib Count: 8-rib
• PACCAR OEM Belt PN: 2012133, 1811269
• Aftermarket Cross-References:
  • Gates: K080945HD
  • Dayco: 5080945
  • Continental: 4080945
• Belt Tensioner Assembly PN:
  • PACCAR: 1811596
  • Gates: 38609
  • Dayco: 89609
• Idler Pulley PN:
  • PACCAR: 1819620PE
  • Gates: 36314
  • Dayco: 89178

Belt Routing for 2016 Kenworth T680 (PACCAR MX-13)

The serpentine belt on a PACCAR MX-13 engine follows a specific path to power all the engine-driven accessories. Since a diagram isn't available, it is critical to take a clear photo or draw a diagram of the belt routing before you begin removal. This will be your best guide for installation.

The belt path is typically as follows:

1. Starts at the main crankshaft pulley at the bottom of the engine.
2. Wraps up and around the A/C compressor pulley.
3. Goes down and around a smooth idler pulley.
4. Travels up to the alternator pulley.
5. Comes across and down to the power steering pump pulley.
6. Goes underneath the water pump pulley.
7. Finishes by wrapping around the automatic belt tensioner before returning to the crank pulley. The tensioner is the last component in the loop and is what you will move to install the belt.

How to Replace the Serpentine Belt

Replacing the serpentine belt is a manageable task with the right tool. The automatic tensioner has a square hole designed to accept a standard 1/2" or 3/8" drive breaker bar or a dedicated serpentine belt tool.

1. Safety First: Ensure the truck is off, the keys are out of the ignition, and the engine is cool.
2. Verify Routing: Photograph the belt's path as described above.
3. Release Tension: Insert your breaker bar or serpentine belt tool into the square socket on the body of the tensioner pulley. Rotate the tensioner against its spring pressure to loosen the belt. Do not try to turn the bolt in the center of the pulley itself.
4. Remove Old Belt: While holding the tensioner in the released position, carefully slip the old belt off one of the smooth pulleys, like the water pump or an idler.
5. Inspect Pulleys: Before installing the new belt, spin each pulley by hand (with the old belt off). They should spin freely and quietly. A noisy or wobbly pulley indicates a failing bearing, and the pulley (or the entire accessory) should be replaced.
6. Install New Belt: Following the diagram or photo you took earlier, route the new belt around all the pulleys except for one smooth, easily accessible pulley (like the idler or water pump).
7. Final Step: Release the tensioner again using your breaker bar and carefully slide the belt over the final pulley. Once the belt is sitting correctly in all the grooves, slowly release the tensioner, which will automatically apply the correct pressure.
8. Final Check: Double-check that the belt is centered in the grooves of every pulley.

Replacement Interval

For a heavy-duty truck like the T680, the serpentine belt is a critical component. There is no single universal replacement interval, but a general guideline is to inspect the belt at every service interval and plan for replacement every 100,000 to 150,000 miles. Factors like operating conditions (extreme heat or cold) can shorten the belt's life. Always defer to the maintenance schedule provided by Kenworth or the engine manufacturer.

Signs of a Failing Belt or Tensioner

A failing belt or tensioner will give several warning signs. Ignoring them can lead to a breakdown and potential damage to other engine components.

• Squealing Noises: A high-pitched squeal, especially on startup or when the engine is under load (like when the A/C kicks on), is a classic sign of a slipping, worn, or contaminated belt.
• Visible Wear: Inspect the belt for cracks, fraying, glazing (shiny spots), or missing ribs. Any visible damage means the belt needs immediate replacement.
• Tensioner Noise: A rattling or grinding noise coming from the tensioner area indicates the internal bearing is failing.
• Tensioner Pulley Wobble: Visually inspect the tensioner while the engine is running. If the pulley is wobbling or vibrating excessively, the tensioner assembly is worn out.
• Weak Tension: If you can easily twist the belt more than 90 degrees on its longest span, the tensioner spring may be weak and failing to provide adequate pressure.

If you're not comfortable performing this maintenance yourself, you can rely on a certified professional. Find a trusted shop on Repairius. '''