2019 GMC Acadia Serpentine Belt Routing & Replacement Guide

Quick Answer

For the 2019 GMC Acadia with the 3.6L V6 engine, here’s a quick overview of serpentine belt information:

• Belt Length: Approximately 98.7 inches (2507 mm)
• Rib Count: 6-rib
• OEM Belt PN: AC Delco 12674488
• Aftermarket Cross-references:
  • Gates K060987
  • Dayco 5060987
  • Continental Elite 4060987
• Auto-Tensioner PN: AC Delco 12623348
• Idler Pulley PN: AC Delco 12604250

Note: For 2.5L 4-cylinder models, belt length and part numbers will differ. Always verify part numbers with your VIN at a reputable parts supplier.

Belt Routing (3.6L V6 Engine)

Before you begin any work, it is highly recommended to take a clear photograph of the current serpentine belt routing. This will serve as an invaluable reference during reinstallation.

Here's a typical routing for the 3.6L V6 engine in your 2019 GMC Acadia. Remember that the exact path can vary slightly, so your photo is crucial.

Starting from the Crankshaft Pulley (the largest pulley at the bottom, directly driven by the engine):

1. From the Crankshaft Pulley, the belt typically travels up to the A/C Compressor Pulley.
2. From the A/C Compressor Pulley, the belt then routes up and over the Idler Pulley.
3. After the Idler Pulley, the belt generally goes down to the Alternator Pulley.
4. From the Alternator Pulley, the belt continues down to the Power Steering Pump Pulley.
5. Next, the belt moves across and up to the Water Pump Pulley.
6. Finally, from the Water Pump Pulley, the belt goes down to the Automatic Belt Tensioner Pulley. The tensioner keeps the belt snug against all pulleys.

How to Replace the Serpentine Belt

Replacing a serpentine belt can be a moderately challenging DIY task. If you're unsure, it's always best to consult a professional.

Tools you'll likely need:

• Serpentine belt tool or a 3/8-inch drive breaker bar/ratchet (for the tensioner)
• Socket to fit the tensioner (often 15mm or 19mm, but verify)

Steps:

1. Safety First: Ensure the engine is off and cool. Disconnect the negative terminal of the battery for added safety.
2. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square hole or a bolt head where you can apply leverage.
3. Relieve Tension: Insert your serpentine belt tool or breaker bar into the tensioner's square hole (or onto the bolt head) and rotate it to release the belt tension. This will allow the belt to become loose.
4. Remove the Old Belt: While holding the tensioner in the relieved position, carefully slip the old belt off one of the pulleys (usually the smooth idler or a non-grooved pulley is easiest).
5. Inspect Pulleys: With the belt off, take this opportunity to spin each pulley by hand. Listen for any grinding noises or feel for excessive play. Replace any faulty pulleys (idler or tensioner) at this time.
6. Route the New Belt: Following the routing diagram (or your pre-removal photo!), carefully route the new serpentine belt around all pulleys, leaving one pulley (again, typically the idler or a smooth pulley) for last.
7. Apply Tensioner: Again, use your tool to relieve the tensioner, and then slip the new belt over the final pulley.
8. Release Tensioner: Slowly release the tensioner, allowing it to apply the proper pressure to the new belt.
9. Double-Check Routing: Visually inspect all pulleys to ensure the belt is correctly seated in all grooves and that the routing matches your diagram.
10. Reconnect Battery & Test: Reconnect the negative battery terminal. Start the engine and let it run for a few minutes, observing the belt to ensure it tracks smoothly without any wobbling or strange noises.

Replacement Interval

Most serpentine belts are designed to last between 60,000 to 100,000 miles or about 5-7 years. However, this can vary based on driving conditions and manufacturer recommendations. It's a good practice to inspect the belt regularly, especially during oil changes or other routine maintenance.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to a breakdown, as critical components like the power steering, alternator, and A/C compressor rely on this belt.

Signs of a failing serpentine belt:

• Squealing or Chirping Noises: This is one of the most common signs, especially when starting the engine or turning the steering wheel.
• Cracks or Fraying: Visible cracks, splits, or frayed edges on the belt indicate wear and necessitate replacement.
• Glazed or Shiny Appearance: A shiny, glazed surface on the belt suggests it's slipping.
• Loss of Ribs: Missing chunks or ribs from the belt means it's severely degraded.
• Power Steering Failure: If the belt drives the power steering pump, a failure will result in very heavy steering.
• Battery Not Charging: If the alternator isn't spinning, your battery won't charge, leading to a dead battery.
• Overheating: The water pump, driven by the serpentine belt, circulates coolant. A broken belt will cause overheating.

Signs of a failing automatic belt tensioner:

• Excessive Belt Voids/Shaking: If the belt appears to be vibrating or bouncing more than usual, the tensioner might be weak.
• Grinding or Squealing from Tensioner Pulley: The tensioner pulley has a bearing that can wear out, causing noise.
• Misalignment: Sometimes a failing tensioner can cause the belt to be misaligned on the pulleys.
• Belt Slippage: A weak tensioner won't keep proper tension, leading to belt slippage and reduced accessory performance.

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