2020 Chevrolet Silverado 3500HD Serpentine Belt Reference

Quick Answer

• Belt Length (Gas 6.6L L8T): 2400mm (94.5 inches)
• Rib Count: 6-rib
• OEM Belt PN (Gas 6.6L L8T): ACDelco 12693354
• Aftermarket Cross-References (Gas 6.6L L8T):
  • Gates K060945
  • Dayco 5060945
  • Continental Elite 4060945
• Auto-Tensioner PN (Gas 6.6L L8T): ACDelco 12678854
• Idler Pulley PN (Gas 6.6L L8T): ACDelco 12679201 (please verify as some models may have more than one)

Belt Routing (Gas 6.6L L8T)

Before you begin any work, always take a clear photo of the current belt routing! This will be your most valuable reference during reinstallation. The 2020 Chevrolet Silverado 3500HD with the 6.6L L8T gasoline engine typically routes the serpentine belt in a pattern that engages all the accessories efficiently.

Starting from the crankshaft pulley at the bottom, the belt will generally proceed clockwise (when looking at the front of the engine) to the A/C compressor pulley. From there, it will wrap around a smooth idler pulley, then continue up to the alternator pulley. After the alternator, it will typically go to the power steering pump pulley, followed by the water pump pulley (which often has grooves), and finally, it will conclude by engaging the automatic tensioner pulley before returning to the crankshaft pulley. Remember, slight variations can exist, so your photograph is crucial.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2020 Chevrolet Silverado 3500HD is a manageable task for the DIY mechanic with the right tools.

1. Safety First: Ensure the engine is off and cool. Disconnect the negative battery terminal to prevent accidental starting.
2. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square opening, typically 3/8-inch or 1/2-inch, designed to accept a breaker bar or a specialized serpentine belt tool.
3. Relieve Tension: Insert your serpentine belt tool or breaker bar into the square opening of the tensioner. Apply steady leverage to rotate the tensioner, releasing tension on the belt. While holding the tensioner in the open position, carefully slip the old belt off one of the pulleys (usually the idler or a smooth pulley where it's easiest to remove).
4. Remove Old Belt: Once loose, carefully remove the old serpentine belt from all the pulleys.
5. Inspect Pulleys: This is a crucial step! With the belt off, take the opportunity to spin each pulley by hand. Listen for any grinding, squealing, or excessive play, which could indicate a failing bearing. Check for any damage or debris on the pulley surfaces.
6. Route New Belt: Refer to your pre-taken photograph or the routing description above. Start by routing the new belt around all the stationary pulleys, leaving the tensioner pulley for last. Ensure the ribbed side of the belt aligns with ribbed pulleys and the smooth side with smooth idlers.
7. Engage Tensioner: Once the belt is mostly in place, use your serpentine belt tool or breaker bar to again rotate the tensioner, creating enough slack to slip the belt over the tensioner pulley. Slowly release the tensioner, allowing it to apply pressure to the new belt.
8. Double-Check: Visually inspect to ensure the belt is properly seated in all the pulley grooves. Start the engine briefly and listen for any unusual noises. Turn off the engine and re-check the belt alignment.

Replacement Interval

While there isn't a universally specified mileage for serpentine belt replacement across all manufacturers and models, a good general recommendation for the 2020 Chevrolet Silverado 3500HD is to inspect the belt every 30,000 to 50,000 miles or every 3-5 years. Many manufacturers suggest replacement between 60,000 to 100,000 miles, or sooner if signs of wear are present. It's always best to consult your owner's manual for specific recommendations for your vehicle. Factors like extreme temperatures, dusty conditions, and aggressive driving can accelerate wear.

Signs of a Failing Belt or Tensioner

A failing serpentine belt or tensioner can lead to a host of problems since these components drive vital accessories. Be attentive to the following signs:

• Squealing or Chirping Noises: This is one of the most common indicators. A squealing belt can mean it's loose, worn, glazed, or that there's a misaligned pulley. If the noise is intermittent, it might indicate a failing tensioner that isn't maintaining proper tension.
• Cracks, Fraying, or Missing Ribs: Visually inspect the belt. Longitudinal cracks, glazing (a shiny, hardened appearance), fraying edges, or chunks of rubber missing from the ribs are all signs the belt needs immediate replacement.
• Loss of Power Steering or A/C: If the belt is slipping or breaks, accessories like the power steering pump or A/C compressor will stop working.
• Overheating Engine: The water pump is driven by the serpentine belt. If the belt fails, the water pump stops, leading to your engine overheating.
• Battery Light On/Charging Issues: The alternator, also driven by the serpentine belt, charges your battery. A broken or slipping belt will prevent the alternator from functioning, causing your battery light to illuminate and eventually leading to a dead battery.
• Wobbling Tensioner or Idler Pulley: While the engine is running, observe the tensioner and idler pulleys. Excessive wobble or vibration can indicate a worn bearing or a failing spring in the tensioner.

Note on Engine Variation: This article specifically focuses on the 6.6L L8T gasoline engine found in the 2020 Chevrolet Silverado 3500HD. The 6.6L Duramax diesel engine uses a different serpentine belt, tensioner, and pulley configuration and therefore has different part numbers and potentially different routing.

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