2021 GMC Yukon Serpentine Belt: Routing, Replacement, and Part Numbers

Quick Answer

• Belt Length: 2275 mm (89.5 inches)
• Rib Count: 6-rib
• OEM Belt PN: AC Delco 12693998
• Aftermarket Cross-references:
  • Gates K060895
  • Dayco 5060895
  • Continental Elite 4060895
• Auto-Tensioner PN: AC Delco 12696016
• Idler Pulley PN: AC Delco 12678601

Belt Routing (6.2L V8 Engine - L87)

Before you begin any work, take a clear photo of the current belt's routing! This will be your invaluable guide during reinstallation. The serpentine belt on your 2021 GMC Yukon 6.2L V8 (L87 engine) follows a specific path, designed to drive all the essential accessories. Here's a step-by-step description:

1. Begin at the crankshaft pulley, which is the large pulley at the bottom, directly connected to the engine.
2. From the crankshaft, the belt goes to the A/C compressor pulley, typically located on the lower passenger side of the engine.
3. Next, the belt wraps around the idler pulley, positioned above the A/C compressor and helps guide the belt.
4. The belt then travels to the alternator pulley, usually located higher up on the passenger side of the engine.
5. From the alternator, it moves to the power steering pump pulley, located on the driver's side, often lower than the alternator.
6. The belt then engages the water pump pulley, usually centrally located on the front of the engine.
7. Finally, the belt goes to the automatic tensioner pulley, which maintains the correct tension on the belt. This pulley is typically located on the driver's side, somewhat above the power steering pump or water pump.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2021 GMC Yukon requires a few basic tools and a bit of patience. Always ensure the engine is off and cool before attempting any work.

1. Locate the tensioner: Identify the automatic tensioner pulley. It will have a square opening for a serpentine belt tool or a 3/8" breaker bar.
2. Relieve tension: Insert your serpentine belt tool or 3/8" breaker bar into the square opening on the tensioner. Gently rotate the tensioner to release the belt tension. This will allow you to remove the belt from the pulleys.
3. Remove the old belt: Once the tension is relieved, carefully pull the old belt off all the pulleys. Start with the easiest one, such as the idler or a smooth pulley.
4. Inspect pulleys: Before installing the new belt, take this opportunity to inspect all the pulleys for any signs of wear, wobbling, or excessive play. Ensure they spin freely and quietly. Replace any worn idler pulleys or tensioners as needed.
5. Route the new belt: Refer to the photo you took earlier or the description above to route the new belt correctly around all the pulleys. Ensure the ribbed side of the belt sits correctly in the grooved pulleys and the smooth side runs on smooth pulleys.
6. Tension the belt: With the belt properly routed, slowly release the tensioner. The tensioner will automatically apply the correct tension to the new belt.
7. Double-check: Once installed, visually inspect the entire belt path to ensure it's seated correctly on all pulleys and there are no twists or misalignments. Start the engine briefly to confirm proper operation and listen for any unusual noises.

Replacement Interval

For most modern vehicles like the 2021 GMC Yukon, the serpentine belt is designed for a long service life. It's generally recommended to inspect the serpentine belt every 30,000 to 50,000 miles or every 3-5 years. Replacement is typically advised between 60,000 to 100,000 miles, or if signs of wear become evident during inspection. Always refer to your owner's manual for the most accurate and up-to-date maintenance schedule for your specific vehicle.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to serious issues, as these components drive critical systems in your vehicle. Be aware of the following warning signs:

• Squealing or Chirping Noises: This is one of the most common signs. A slipping or worn belt often produces a high-pitched squeal, especially during cold starts or when turning the steering wheel.
• Visible Cracks or Fraying: Inspect the belt for cracks, splits, fraying edges, or chunking (pieces of the belt missing). These are clear indicators that the belt needs to be replaced.
• Glazed or Shiny Belt Surface: A glazed appearance on the ribbed side of the belt can indicate slippage and reduced friction.
• Loss of Power Steering, A/C, or Charging System Issues: Since the serpentine belt drives these accessories, a broken or severely slipping belt will result in a loss of power steering assist, non-functioning air conditioning, and potentially a dead battery (as the alternator won't be charging).
• Wobbling or Excessive Play in Pulleys: If the automatic tensioner or any idler pulley is worn, it may wobble or have excessive play. This can cause belt misalignment and premature belt wear.
• Tensioner Not Moving: The automatic tensioner should maintain consistent tension. If it appears stuck, not moving, or not providing adequate tension, it needs to be replaced.

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