2020 GMC Sierra 2500HD: Serpentine Belt

Quick Answer

• Belt Length: 2413 mm (95 in)
• Rib Count: 6-rib
• OEM Belt Part Number: 12693488
• Aftermarket Cross-References:
  • Gates: K060950
  • Dayco: 5060950
  • Continental Elite: 4060950
• Auto-Tensioner Part Number: 12690920
• Idler Pulley Part Number: 12690919

Note: The part numbers above apply to the 6.6L L8T V8 gasoline engine. The 6.6L Duramax L5P diesel engine uses a different belt and components. Always verify the part numbers with your VIN before purchasing.

Belt Routing

Before removing the old serpentine belt, we strongly recommend taking a clear photograph of the belt's path for reference. The routing for the 6.6L V8 gas engine is as follows:

1. The belt wraps around the crankshaft pulley at the bottom of the engine.
2. From the crankshaft, the belt moves up to the A/C compressor.
3. Next, it goes around the idler pulley.
4. The belt then routes to the alternator.
5. From the alternator, it goes to the power steering pump pulley.
6. Then, it wraps around the water pump pulley.
7. Finally, the belt goes under the tensioner pulley to complete the loop.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2020 GMC Sierra 2500HD is a manageable task for a DIYer with the right tools. You'll need a serpentine belt tool or a long 3/8" drive breaker bar to release the tension on the belt.

1. Locate the tensioner: The automatic belt tensioner is located between the water pump and the crankshaft pulley.
2. Release tension: Insert the 3/8" square drive of your tool into the designated slot on the tensioner arm. Rotate the tensioner clockwise to release the belt tension.
3. Remove the old belt: While holding the tensioner, carefully slip the belt off one of the smooth pulleys, like the water pump or idler pulley. Then, slowly release the tensioner and remove the old belt completely.
4. Install the new belt: Following the routing path you photographed earlier (or our description above), begin to route the new belt around all the pulleys, saving a smooth, easily accessible pulley for last.
5. Finalize installation: Once the belt is routed correctly, release the tensioner again and slip the belt over the final pulley. Double-check that the belt is correctly seated in the grooves of all ribbed pulleys. A misaligned belt will quickly shred itself.

Replacement Interval

General recommendations for serpentine belt replacement are typically between 60,000 and 100,000 miles. However, you should inspect the belt regularly, especially during other routine maintenance like oil changes.

Signs of a Failing Belt or Tensioner

It's crucial to replace a worn belt or failing tensioner before they fail completely, which could leave you stranded.

Signs of a bad belt:

• Squealing or chirping sounds: This is often the first sign of a slipping or misaligned belt.
• Visible wear: Look for cracks, fraying, glazing (shiny spots), or missing ribs on the belt.

Signs of a bad tensioner:

• Grinding or rattling noises: This could indicate a failing bearing in the tensioner pulley.
• Excessive belt flutter: If you see the belt vibrating or flapping while the engine is running, the tensioner may not be providing adequate tension.
• Tensioner arm bounce: The tensioner arm should remain relatively steady. If it's bouncing erratically, it needs to be replaced.

If you're not comfortable performing this maintenance yourself, you can find a trusted shop on Repairius.