2023 Subaru Forester Serpentine Belt: Routing, Replacement, and Part Numbers

Quick Answer

• Belt Length: Approximately 88.0 inches (2235 mm)
• Rib Count: 6-rib
• OEM Belt PN: 809221150 (Subaru)
• Aftermarket Cross-Reference:
  • Gates K060880
  • Dayco 5060880
  • Continental Elite 4060880
• Auto-Tensioner PN: 23769AA00A (Subaru)
• Idler Pulley PN: 23770AA020 (Subaru)

Belt Routing

The 2023 Subaru Forester, typically equipped with the 2.5L naturally aspirated BOXER engine, uses a single serpentine belt to drive all accessories. Before you begin any work, always take a clear photograph of the current belt routing! This will be your infallible guide during reinstallation.

Here's a text-based description of the routing path:

1. Begin at the Crankshaft Pulley (the largest pulley at the bottom front of the engine).
2. From the crankshaft, the belt goes up and to the left to the A/C Compressor Pulley.
3. From the A/C compressor, the belt goes horizontally to the right to the Idler Pulley (a smooth pulley that guides the belt).
4. From the idler pulley, the belt goes up to the Alternator Pulley (usually at the top of the engine compartment).
5. From the alternator, the belt goes down and to the left to the Power Steering Pump Pulley (if equipped, some models have electric power steering and no pump).
6. From the power steering pump (or direct from the alternator on electric power steering models), the belt goes down to the Water Pump Pulley.
7. Finally, from the water pump, the belt wraps around the Automatic Belt Tensioner and then returns to the crankshaft pulley, completing the loop.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2023 Subaru Forester is a manageable DIY task, but requires the right tools and a careful approach.

1. Safety First: Ensure the engine is cool and the vehicle is securely parked with the engine off. Disconnect the negative terminal of the battery.
2. Locate the Tensioner: Identify the automatic belt tensioner. It typically has a square opening (often 3/8-inch or 1/2-inch drive) designed for a breaker bar or a specialized serpentine belt tool.
3. Relieve Tension: Insert your serpentine belt tool or a 3/8-inch drive breaker bar into the square opening on the tensioner. Apply steady leverage to rotate the tensioner arm, releasing tension on the belt. While holding the tensioner in the loosened position, carefully slip the belt off one of the easier pulleys (like the alternator or idler).
4. Remove Old Belt: Once slack, completely remove the old serpentine belt from all pulleys.
5. Inspect Pulleys: Take this opportunity to inspect all pulleys for any signs of wear, wobbling, or excessive play. A failing pulley can quickly damage a new belt.
6. Route New Belt: Refer to the photograph you took earlier and begin routing the new belt, ensuring it sits correctly in all the pulley grooves. It's often easiest to leave the belt off the automatic tensioner pulley until last.
7. Final Tensioning: Once the belt is routed over all other pulleys, use your serpentine belt tool or breaker bar to again pivot the tensioner, creating enough slack to slip the belt over the tensioner pulley. Slowly release the tensioner, allowing it to apply proper tension to the new belt.
8. Double-Check: Visually inspect the entire belt path to confirm the belt is seated correctly in all grooves and on all pulleys. Start the engine briefly (once battery is reconnected) and listen for any abnormal noises. Monitor the belt for proper operation.

Replacement Interval

Subaru typically recommends inspecting the serpentine belt at every scheduled maintenance interval (e.g., every 30,000 miles or 30 months) and replacing it as needed. Generally, a serpentine belt will last between 60,000 to 100,000 miles, but this can vary based on driving conditions and engine bay temperatures. Always consult your owner's manual for the most accurate and up-to-date maintenance schedule for your specific vehicle.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to serious issues, as vital accessories like the alternator, power steering, and A/C compressor would cease to function. Here are the common warning signs:

• Squealing or Chirping Noises: This is one of the most common indicators. It often occurs during cold starts, acceleration, or when turning the steering wheel. It can be caused by a worn belt, misaligned pulleys, or a failing tensioner.
• Cracks, Fraying, or Glazing on the Belt: Visually inspect the belt. If you see cracks (especially across the ribs), fraying edges, chunks missing, or a shiny, glazed appearance on the ribbed side, it's time for replacement.
• Loss of Power Steering, A/C, or Charging System Issues: If the belt breaks, these systems will immediately stop working. You might notice the battery light illuminating, indicating the alternator isn't charging.
• Vibration or Shuddering: A worn or damaged belt can cause vibrations that are felt through the steering wheel or floorboards.
• Loose or Wobbly Tensioner/Pulleys: If the automatic tensioner arm is not providing consistent tension, or if any pulleys wobble when the engine is running, they need to be inspected and likely replaced. A failing tensioner might also produce a rattling or clunking sound.

Regular inspection is key to catching these issues before they lead to a breakdown.

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