2016 GMC Sierra 2500HD Serpentine Belt Routing & Replacement Guide

Quick Answer

• Belt Length: Varies by engine (see below)
• Rib Count: 6-rib
• OEM Belt PN (6.0L V8): 12658882
• Aftermarket Cross-Reference (6.0L V8):
  • Gates K061039
  • Dayco 5061040
  • Continental Elite 4061040
• OEM Belt PN (6.6L Duramax Diesel): 12636224
• Aftermarket Cross-Reference (6.6L Duramax Diesel):
  • Gates K061066
  • Dayco 5061065
  • Continental Elite 4061065
• Auto-Tensioner PN (6.0L V8): 12605177 (AC Delco 38159)
• Auto-Tensioner PN (6.6L Duramax Diesel): 12622441 (AC Delco 38161)
• Idler Pulley PN (6.0L V8): 12627993 (AC Delco 38006)
• Idler Pulley PN (6.6L Duramax Diesel): 12627993 (AC Delco 38006)

Belt Routing

The 2016 GMC Sierra 2500HD serpentine belt routing can vary slightly depending on the engine (6.0L V8 gasoline or 6.6L Duramax Diesel). Before you begin any belt removal, always take a clear photograph of the existing belt routing. This will serve as an invaluable reference during reinstallation.

General Routing (6.0L V8 & 6.6L Duramax Diesel - confirm with your photo):

1. Starting from the crankshaft pulley (usually the largest, lowest pulley).
2. The belt typically routes up and over the A/C compressor pulley.
3. From the A/C compressor, it will go to an idler pulley.
4. The belt then routes to the alternator pulley.
5. From the alternator, it will go to the power steering pump pulley.
6. The belt will then wrap around the water pump pulley.
7. Finally, the belt will route around the automatic tensioner pulley, which provides the necessary tension for the belt.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2016 GMC Sierra 2500HD is a manageable DIY task, but it requires the right tools and a careful approach.

Tools Needed:

• Serpentine belt tool kit (recommended) or a 3/8-inch drive breaker bar/ratchet and appropriate socket/external torx bit for the tensioner pulley bolt.
• New serpentine belt.

Steps:

1. Safety First: Ensure the engine is off and cool. Disconnect the negative battery terminal to prevent accidental starting.
2. Document: As mentioned, take a clear photo of the current belt routing.
3. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square hole (for a 3/8-inch drive tool) or a hexagonal bolt head.
4. Relieve Tension: Insert your serpentine belt tool or breaker bar into the tensioner's square hole (or use the appropriate socket on the bolt head). Rotate the tensioner to relieve tension on the belt. You will need to hold it in this position.
5. Remove Old Belt: While holding the tensioner open, slip the old belt off one of the pulleys (usually one of the smoother idler pulleys or the power steering pump pulley is easiest).
6. Inspect Pulleys: Once the old belt is off, carefully inspect all the pulleys for any signs of wear, wobbling, or excessive noise. Replace any worn idler pulleys or other components as needed.
7. Install New Belt: Route the new belt according to your photograph. This is usually the trickiest part. Make sure the V-ribs of the belt are properly seated in the grooves of all the pulleys.
8. Tension and Release: Once the belt is correctly routed, slowly release the tensioner. Double-check that the belt is correctly seated on all pulleys.
9. Reconnect Battery: Reconnect the negative battery terminal.
10. Test: Start the engine and let it run for a few minutes, observing the new belt for proper operation, alignment, and any unusual noises. Turn the steering wheel lock-to-lock a few times to ensure power steering is functioning correctly.

Replacement Interval

For the 2016 GMC Sierra 2500HD, 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 are observed. However, always refer to your vehicle's owner's manual for the most accurate and manufacturer-specific recommendations. Driving conditions can also affect belt life; vehicles used for heavy towing or in extreme temperatures may require more frequent inspection and replacement.

Signs of a Failing Belt or Tensioner

Don't wait for a complete belt failure that leaves you stranded. Be aware of these common signs of a worn serpentine belt or a failing tensioner:

• Squealing or Chirping Noises: This is one of the most common indicators. A loose or worn belt, or a failing pulley/tensioner, can cause a high-pitched squeal, especially on startup, during acceleration, or when turning the steering wheel.
• Cracks, Fraying, or Glazing on the Belt: Visually inspect the belt. If you see cracks, missing ribs, fraying edges, or a shiny, glazed appearance on the ribbed side, it's time for a replacement.
• Loss of Power Steering, A/C, or Alternator Function: Since the serpentine belt drives these accessories, a broken or severely slipping belt will result in a loss of these functions. Your battery light might come on if the alternator isn't charging.
• Vibration or Shaking: A worn belt or failing tensioner/pulley can cause vibrations that you might feel in the steering wheel or through the vehicle.
• Tensioner Movement/Wobble: With the engine off, check the tensioner pulley. It should be firm. If it wiggles excessively or appears to be off-center, the tensioner itself might be failing.
• Fluid Leaks: While not directly a belt failure, fluid leaks (oil, coolant) can contaminate the belt, causing it to slip and wear prematurely.

Addressing these signs promptly can prevent more extensive damage and keep your truck running reliably.

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