2018 Chevrolet Silverado 3500HD Serpentine Belt Routing & Part Numbers

Quick Answer

For your 2018 Chevrolet Silverado 3500HD, the serpentine belt system can vary slightly depending on the engine. The most common engine is the 6.6L Duramax Diesel (LML or L5P). Please visually confirm your engine before ordering parts.

For 6.6L Duramax Diesel (L5P/LML):

• Belt Length: Approximately 98.0 inches (2490 mm)
• Rib Count: 6-rib
• OEM Belt PN: AC-Delco 12693351
• Aftermarket Cross-references:
  • Gates K060980 (or K060975 for a slightly shorter, tighter fit)
  • Dayco 5060980
  • Continental Elite 4060980
• Auto-Tensioner PN: AC-Delco 12619077 (or Gates 39110)
• Idler Pulley PN: AC-Delco 12619074 (or Gates 36174)

Belt Routing

Important: Before you begin, always take a clear photo of your current serpentine belt routing. This will be your best guide for proper reinstallation.

For the 6.6L Duramax Diesel, the serpentine belt navigates a complex path to drive all essential accessories. Here's a step-by-step description:

1. Begin at the Crankshaft Pulley (the largest pulley, located at the very bottom, typically grooved).
2. From the crankshaft, the belt typically goes up and to the right to engage the A/C Compressor Pulley.
3. From the A/C compressor, the belt routes over an Idler Pulley, usually situated above the A/C compressor or slightly to the left.
4. After the idler, the belt often runs down and to the left to the Alternator Pulley.
5. From the alternator, the belt will stretch across to the Power Steering Pump Pulley.
6. Next, the belt moves to the Water Pump Pulley, often located near the center-top of the engine.
7. Finally, the belt loops under the Auto-Tensioner Pulley, which provides the necessary tension to keep the belt snug on all pulleys before routing back to the crankshaft pulley.

Always double-check your specific engine configuration as variations can occur.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your Silverado 3500HD 6.6L Duramax Diesel typically requires a serpentine belt tool or a long 3/8-inch breaker bar. The automatic tensioner has a square drive opening designed for this tool.

1. Safety First: Ensure the engine is off and cool. Disconnect the negative battery terminal.
2. Locate the Tensioner: Identify the automatic belt tensioner. It will have a pulley and a square opening for your tool.
3. Release Tension: Insert your serpentine belt tool or breaker bar into the tensioner's square opening. Apply leverage to rotate the tensioner assembly, relieving tension on the belt. Note which way the tensioner moves.
4. Remove Old Belt: While holding the tensioner in the loosened position, carefully slip the belt off one of the pulleys (often the idler or alternator is easiest).
5. Inspect Pulleys: With the old belt removed, inspect all pulleys for any signs of wear, damage, or excessive play. Ensure they spin freely without noise or wobble.
6. Route New Belt: Refer to the photo you took earlier and the routing description above. Begin routing the new belt around all fixed pulleys first, leaving the tensioner pulley for last, or one of the most accessible pulleys.
7. Apply Tension: Once the belt is mostly in place, use your tool to again rotate the tensioner, allowing enough slack to slip the belt fully onto the final pulley.
8. Verify Routing: Slowly release the tensioner and visually confirm that the belt is correctly seated in all pulley grooves.
9. Reconnect Battery: Reconnect the negative battery terminal.
10. Test: Start the engine and let it run for a minute, listening for any squealing or unusual noises. Turn off the engine and re-check the belt routing and tension.

Replacement Interval

General recommendations for serpentine belt replacement on a 2018 Chevrolet Silverado 3500HD with the 6.6L Duramax Diesel typically fall between 60,000 to 100,000 miles, or every 5-7 years, whichever comes first. However, it's crucial to perform a visual inspection at every oil change or major service. Severe operating conditions, such as consistent towing, extreme temperatures, or dusty environments, may necessitate earlier replacement.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to a breakdown, as it drives critical components like your alternator, power steering pump, and water pump. Here are the signs to watch for:

• Squealing or Chirping Noises: This is often the most common symptom. It can indicate a worn or misaligned belt, or a failing tensioner/pulley. The noise might be worse on cold starts or when turning the steering wheel.
• Cracks, Fraying, Glazing, or Missing Ribs on the Belt: Visually inspect the belt's surface for any signs of wear. Glazing (a shiny, hardened appearance) suggests the belt is slipping. Deep cracks or missing chunks mean immediate replacement is needed.
• Battery Light On: Since the alternator is driven by the serpentine belt, a broken or slipping belt can lead to insufficient charging, triggering the battery warning light.
• Loss of Power Steering: If the power steering pump isn't being driven, steering will become significantly harder.
• Engine Overheating: A failing water pump (due to a slipping or broken belt) will prevent proper coolant circulation, leading to engine overheating.
• Accessory Malfunction: Any accessory driven by the belt (A/C, alternator, power steering) may exhibit reduced performance or complete failure.
• Wobbling or Excessive Play in Pulleys/Tensioner: With the engine off, check pulleys for excessive side-to-side movement. A tensioner that doesn't provide consistent tension can cause the belt to flap or come off.

Address these symptoms promptly to avoid further damage and ensure reliable operation of your truck.

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