2020 Chevrolet Silverado 2500HD Serpentine Belt Routing & Part Numbers

Quick Answer

The 2020 Chevrolet Silverado 2500HD, equipped with either the 6.6L V8 L8T (gasoline) or the 6.6L Duramax L5P (diesel), utilizes a single serpentine belt system. Always verify your engine type before purchasing parts, as some components may differ.

6.6L V8 L8T (Gasoline)

• Belt Length & Rib Count: 2305mm (90.75 inches), 6-rib
• OEM Belt PN: AC Delco 12678604
• Aftermarket Cross-references:
  • Gates K060907
  • Dayco 5060908
  • Continental Elite 4060907
• Auto-Tensioner PN: AC Delco 12678128
• Idler Pulley PN: AC Delco 12678126

6.6L Duramax L5P (Diesel)

• Belt Length & Rib Count: 2695mm (106.1 inches), 8-rib (main drive belt)
• OEM Belt PN: AC Delco 12678127 (main drive belt)
• Aftermarket Cross-references:
  • Gates K081061
  • Dayco 5081060
  • Continental Elite 4081060
• Auto-Tensioner PN: AC Delco 12678128 (often shared with gas engine, but verify)
• Idler Pulley PN: AC Delco 12678126 (often shared with gas engine, but verify)

Belt Routing

Always photograph your existing belt routing before removal! This is the most crucial step to ensure correct reinstallation, especially since diagrams can vary slightly by model year or even production run. The following describes a common routing path for both engines, but always refer to your photographic evidence.

6.6L V8 L8T (Gasoline) & 6.6L Duramax L5P (Diesel) - Typical Main Drive Belt Routing

1. Begin at the Crankshaft Pulley (the largest, lowest pulley).
2. From the crankshaft, the belt typically runs up to the A/C Compressor Pulley.
3. From the A/C compressor, the belt may go to an Idler Pulley, which helps guide the belt.
4. Next, the belt often routes to the Alternator Pulley.
5. From the alternator, it will generally wrap around the Power Steering Pump Pulley.
6. The belt then usually goes to the Water Pump Pulley.
7. Finally, the belt will engage the Automatic Belt Tensioner, completing the path. The tensioner maintains proper belt tension across all accessories.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2020 Chevrolet Silverado 2500HD requires a few basic tools and careful attention:

1. Safety First: Ensure the engine is off and cool. Disconnect the negative battery terminal to prevent accidental starting.
2. Document: As mentioned, take clear photos of the current belt routing from multiple angles.
3. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square drive hole (usually 3/8" or 1/2") or a hex head for a wrench.
4. Relieve Tension: Insert a serpentine belt tool or a breaker bar (with the appropriate socket or adapter) into the tensioner's drive hole. Rotate the tensioner to relieve tension on the belt. Note: You will be rotating it against spring tension, so it may require some force.
5. Remove Old Belt: While holding the tensioner in the loosened position, slip the old belt off one of the pulleys (usually one near the tensioner). Once loose, you can release the tensioner and remove the belt entirely.
6. Inspect Pulleys: With the old belt off, inspect all pulleys for any signs of wear, wobble, or difficulty spinning. Replace any worn idler pulleys or the auto-tensioner if it feels weak or does not move smoothly.
7. Install New Belt: Route the new serpentine belt according to your photographs and the routing description, ensuring it is correctly seated in all pulley grooves. The last pulley to route should be one that allows you to easily slip the belt over it while relieving tension with your tool.
8. Tension and Verify: Once the belt is fully routed, slowly release the tensioner. Double-check that the belt is properly seated in all pulley grooves and there are no twists or misalignments.
9. Reconnect Battery & Test: Reconnect the negative battery terminal. Start the engine and visually inspect the belt's operation. Listen for any squealing or unusual noises. If the belt slips or squeals, shut off the engine and re-verify the routing and tension.

Replacement Interval

Chevrolet generally recommends inspecting the serpentine belt at every oil change or major service interval (e.g., every 15,000 to 20,000 miles) and replacing it as needed. While belts are designed for longevity, typically lasting 60,000 to 100,000 miles under normal conditions, factors like extreme temperatures, contamination (oil, coolant), and heavy use can shorten their lifespan. It's wise to replace the belt proactively if any signs of wear are observed during inspection.

Signs of a Failing Belt or Tensioner

• Squealing or Chirping Noises: This is one of the most common indicators of a failing belt or tensioner. It can mean the belt is slipping, worn, or the tensioner is no longer providing adequate force.
• Visible Cracks, Fraying, or Glazing: Inspect the belt's ribbed surface. Cracks, missing chunks, fraying edges, or a shiny, glazed appearance are clear signs the belt is deteriorating and needs replacement.
• Power Loss or Malfunctions of Accessories: Since the serpentine belt drives accessories like the power steering pump, alternator, and A/C compressor, a failing belt can lead to dimming headlights (alternator), heavy steering (power steering), or loss of air conditioning.
• Vibration or Rattle: A failing auto-tensioner or worn idler pulley can cause vibrations, rattles, or clunking sounds from the front of the engine.
• Belt Slipping Off Pulleys: If the belt repeatedly slips off a pulley, it's a critical sign of a severely worn belt, a faulty tensioner, or a misaligned pulley.
• Indicator Light: In some cases, a "battery" or "check engine" light might illuminate if the alternator isn't charging correctly due to a slipping or broken belt.

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