2015 GMC Sierra 1500 Serpentine Belt: Routing, Replacement, & Part Numbers

Quick Answer

• Belt Length: Approximately 104.5 inches (for models with 5.3L and 6.2L engines)
• Rib Count: 6-rib
• OEM Belt PN: AC-Delco 6K1044
• Aftermarket Cross-references:
  • Gates K061045
  • Dayco 5061045
  • Continental Elite 4061045
• Auto-Tensioner PN: Gates 38328 (or AC-Delco 12627760)
• Idler Pulley PN: Gates 36174 (or AC-Delco 12627993)

(Note: Always verify part numbers with your VIN for exact fitment, as some variations may exist, especially with different engine options like the 4.3L V6.)

Belt Routing

Before you begin any work, take a clear, well-lit photograph of your current serpentine belt routing! This will be your most valuable reference during reinstallation, especially since we can't provide an image here. The 2015 GMC Sierra 1500, particularly with the prevalent 5.3L and 6.2L V8 engines, generally follows a common path.

Here's a step-by-step description of the routing path:

1. Crankshaft Pulley: Start at the largest, lowest pulley—the crankshaft pulley. The belt wraps around the bottom of this pulley.
2. A/C Compressor: From the crankshaft, the belt travels upwards to the A/C compressor pulley. It typically wraps over the top of this pulley.
3. Idler Pulley (Smooth): After the A/C compressor, the belt may pass under a smooth idler pulley, which helps guide the belt.
4. Alternator: The belt then heads up to the alternator, generally wrapping around the top of the alternator pulley.
5. Power Steering Pump: From the alternator, the belt usually goes down to the power steering pump pulley, wrapping around the top or bottom depending on its position relative to the alternator.
6. Water Pump: Next, the belt typically wraps around the water pump pulley. This is often an unribbed, smooth pulley that the back (smooth) side of the belt rides on.
7. Auto-Tensioner: Finally, the belt goes to the auto-tensioner pulley. This pulley will have the ribbed side of the belt making contact and is where you'll apply leverage to release tension for removal or installation.

Remember, your specific engine (4.3L V6, 5.3L V8, or 6.2L V8) might have slight variations in the exact layout, but the general sequence of components remains similar. Always consult your photograph!

How to Replace the Serpentine Belt

Replacing a serpentine belt on your 2015 GMC Sierra 1500 is a manageable DIY task, though it requires a bit of leverage.

Tools Needed:

• Serpentine belt tool or a 3/8" drive breaker bar/ratchet (the tensioner arm usually has a square hole for this)
• New serpentine belt
• Possibly a diagram (your photo!) for routing

Steps:

1. Locate the Tensioner: Find the automatic belt tensioner. It will have a pulley and an arm with a square hole (often 3/8-inch). You'll need to access this from under the hood, usually on the passenger side of the engine.
2. Relieve Tension: Insert your serpentine belt tool or breaker bar into the square hole on the tensioner arm. Rotate the tool/bar clockwise (most common for this application, but verify by observing the tensioner arm movement) to pivot the tensioner arm and release the tension on the belt. Hold it in this position.
3. Remove Old Belt: While holding the tensioner open, carefully slip the old belt off one of the easier pulleys (like the alternator or A/C compressor).
4. Inspect Pulleys: With the belt off, take this opportunity to spin each pulley by hand. Listen for any grinding, squeaking, or roughness, and check for excessive play. This is a good time to consider replacing any noisy or wobbly idler pulleys or the tensioner itself if it feels loose or sluggish.
5. Route New Belt: Refer to your photograph and the routing description. Carefully route the new serpentine belt around all pulleys except for the last one (often the tensioner or an idler pulley, whichever is easiest to slip the belt over last). Ensure the ribbed side of the belt aligns with ribbed pulleys and the smooth back side aligns with smooth pulleys (like the water pump).
6. Final Installation: Once the belt is mostly routed, again apply pressure to the tensioner with your tool to relieve tension. Slip the belt over the final pulley. Slowly release the tensioner, ensuring the belt seats correctly on all pulleys.
7. Double-Check: Before starting the engine, visually inspect the entire belt routing one last time to ensure it is perfectly seated on all pulleys and not twisted.

Replacement Interval

GMC generally recommends inspecting the serpentine belt at every oil change or major service interval (e.g., every 15,000 to 30,000 miles) and replacement around 60,000 to 100,000 miles, or sooner if signs of wear are present. Factors like extreme temperatures, dust, and fluid contamination can shorten its lifespan. It's often a good practice to replace the belt tensioner and idler pulleys when replacing a high-mileage belt, as these components tend to wear out around the same time.

Signs of a Failing Belt or Tensioner

Don't wait for your belt to snap! Here are common signs that your serpentine belt or its tensioner might be failing:

• Squealing or Chirping Noises: A common sign, especially on cold starts, during acceleration, or when turning the steering wheel. This could indicate a worn belt, a misaligned pulley, or a failing tensioner that isn't providing adequate tension.
• Cracks, Fraying, or Glazing: Visually inspect the belt. Deep cracks, missing chunks, fraying edges, or a smooth, shiny (glazed) appearance on the ribbed side are all signs of wear that necessitate replacement.
• Loss of Power Steering, A/C, or Charging: If the belt breaks or slips severely, you'll immediately lose power to all the accessories it drives. Your power steering will become very heavy, your A/C will stop blowing cold, and your battery warning light will illuminate as the alternator stops charging.
• Wobbling or Vibrating Pulley: A wobbly idler pulley or tensioner pulley indicates a worn bearing and should be replaced immediately.
• Tensioner Not Moving or Stiff: If the automatic tensioner does not move freely or appears seized, it's not effectively keeping the belt tight, leading to slippage and premature belt wear.
• Unusual Grinding or Growling Noises: While less common for just the belt, these noises often point to a failing bearing in an accessory (alternator, A/C compressor, power steering pump) or an idler/tensioner pulley.

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