2015 Nissan Altima Serpentine Belt - Routing, Replacement, and Part Numbers

Quick Answer

For 2.5L 4-Cylinder models (QR25DE engine):

• Belt Length: 69.2 inches (1758 mm)
• Rib Count: 6-rib
• OEM Belt PN: 11720-3TA0A
• Aftermarket Cross-references:
  • Gates K060692
  • Dayco 5060690
  • Continental Elite 4060692
• Auto-Tensioner PN: 11750-3TA0A
• Idler Pulley PN: 11925-3TA0A (Note: Some 2.5L models may not have a dedicated idler pulley depending on accessory layout; verify your specific vehicle).

For 3.5L V6 models (VQ35DE engine):

• Belt Length: Approximately 88.5 inches (2248 mm) - Note: Length can vary slightly by manufacturer. Always confirm prior to purchase.
• Rib Count: 6-rib
• OEM Belt PN: 11720-JA10B (for main accessory belt)
• Aftermarket Cross-references:
  • Gates K060882 (or similar, verify for V6)
  • Dayco 5060882 (or similar, verify for V6)
  • Continental Elite 4060882 (or similar, verify for V6)
• Auto-Tensioner PN: 11750-JA00A
• Idler Pulley PN: 11925-JA00A (multiple idlers may be present on V6; verify all needed for replacement).

Always confirm part numbers with a reputable parts supplier using your VIN to ensure proper fitment for your specific 2015 Nissan Altima, as variations can occur even within the same model year and engine option.

Belt Routing

Before you begin any work, take a clear photograph of the existing serpentine belt routing. This will be your invaluable guide for correct reinstallation.

For 2.5L 4-Cylinder models:

The serpentine belt on the 2.5L Nissan Altima primarily drives the alternator, power steering pump, water pump, and A/C compressor. Here's a typical routing path, starting from the crankshaft pulley:

1. From the Crankshaft Pulley, the belt typically travels down to the A/C Compressor pulley.
2. From the A/C Compressor, the belt then goes up (often skipping an idler on these models, or going over a small, dedicated idler if present) towards the Alternator pulley.
3. From the Alternator, the belt generally moves across to the Power Steering Pump pulley.
4. After the Power Steering Pump, it usually routes down to the Water Pump pulley.
5. Finally, from the Water Pump, the belt engages with the Automatic Belt Tensioner pulley, before returning to the Crankshaft Pulley, completing the loop. The tensioner ensures consistent belt tension.

For 3.5L V6 models:

The V6 engine often has a more complex routing due to additional accessories or different placements. While a precise text description is challenging without an image, here's a general path, noting there are often multiple idler pulleys involved. Always refer to your photographic evidence and a diagram specific to your VIN.

1. Starting at the Crankshaft Pulley, the belt usually goes to the A/C Compressor.
2. From the A/C Compressor, it will route through one or more Idler Pulleys.
3. It then typically engages the Alternator pulley.
4. Following the Alternator, it will likely pass over another Idler Pulley or directly to the Power Steering Pump.
5. The belt will then wrap around the Water Pump pulley.
6. Finally, it will route to the Automatic Belt Tensioner before returning to the Crankshaft, completing the path.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2015 Nissan Altima is a manageable DIY task for many, but requires care. The primary tool you'll need is a serpentine belt tool or a 3/8-inch breaker bar/ratchet.

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 (usually 3/8-inch or 1/2-inch) designed for a breaker bar or serpentine belt tool.
3. Relieve Tension: Insert your breaker bar or serpentine belt tool into the tensioner's square opening. Apply steady pressure in the direction that loosens the belt (typically clockwise for 2.5L models, check your specific tensioner). This will rotate the tensioner pulley and slacken the belt.
4. Remove the Old Belt: While holding the tensioner, carefully slip the old belt off one of the accessories (e.g., the alternator or idler pulley). Once it's off one pulley, you can slowly release the tensioner and remove the belt completely.
5. Inspect Pulleys: With the belt off, take this opportunity to manually spin each pulley (alternator, A/C compressor, power steering, idlers, water pump). They should spin smoothly with no wobble, grinding, or excessive play. Inspect the auto-tensioner for proper tension and ensure it's not seized.
6. Route the New Belt: Carefully route the new serpentine belt according to the diagram you photographed earlier. This is often the trickiest part. Make sure the ribs of the belt are properly seated in all the pulley grooves.
7. Final Tensioning: Once the belt is mostly routed, apply tension again with your tool to the automatic tensioner. Slip the last section of the belt onto the final pulley. Double-check that all ribs are perfectly aligned on all pulleys.
8. Verify: Release the tensioner slowly. The tensioner should apply firm pressure to the belt. Give all pulleys a visual inspection to ensure the belt is correctly seated.
9. Reconnect Battery: Reconnect the negative battery terminal. Start the engine and listen for any abnormal noises (squealing, chirping). If the belt seems to slip or make noise, shut off the engine and re-check the routing and tension.

Replacement Interval

Nissan generally recommends inspecting the serpentine belt at every service interval (typically every 15,000 miles or 12 months) and replacing it as needed. A common replacement interval for serpentine belts is between 60,000 to 100,000 miles, or when signs of wear become apparent. However, driving conditions and climate can affect its lifespan. It's more important to replace based on condition rather than strictly mileage.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to serious issues, including loss of power steering, A/C, alternator charging, and engine overheating. Watch out for these warning signs:

• Squealing or Chirping Noises: This is the most common symptom. It often indicates a worn, glazed, or misaligned belt, or a failing tensioner/pulley.
• Visible Cracks, Fraying, or Glazing: Inspect the belt's ribbed surface. Cracks, missing chunks, or a shiny, glazed appearance are clear indicators it's time for replacement.
• Loose or Wobbly Pulleys: If you notice any pulleys wobbling or spinning with resistance when the engine is off and belt is removed, they need attention.
• Power Steering or A/C Malfunction: If the belt is slipping or broken, accessories like your power steering and A/C compressor will stop working.
• Battery Light On: A broken or slipping belt will prevent the alternator from charging, leading to the battery warning light illuminating.
• Overheating Engine: The water pump is driven by the serpentine belt. If the belt fails, the water pump stops, causing the engine to overheat.
• Tensioner Not Centered: The automatic tensioner has an indicator mark. If it's consistently at one extreme of its travel, it may not be providing proper tension, indicating wear.

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