2018 Subaru Forester Serpentine Belt: Routing, Replacement, & Part Numbers

Quick Answer

• Belt Length: Approximately 96.0 inches (2438 mm)
• Rib Count: 6-rib
• OEM Belt PN: Subaru 809221290
• Aftermarket Cross-references:
  • Gates K060960
  • Dayco 5060960
  • Continental Elite 4060960
• Auto-Tensioner PN: Subaru 23769AA002 (or equivalent aftermarket)
• Idler Pulley PN: Subaru 23770AA001 (or equivalent aftermarket)

Belt Routing (2.5L H4 Engine)

The 2018 Subaru Forester, equipped with the 2.5L H4 engine, utilizes a single serpentine belt to drive all accessories. Before you begin any work, always take a clear photo of the existing belt routing! This will be your best guide during reassembly.

Here's a step-by-step description of the belt's path:

1. Begin at the Crankshaft Pulley (the largest pulley at the bottom-center of the engine).
2. From the crankshaft, the belt routes up and to the right to the A/C Compressor Pulley (located on the lower passenger side).
3. From the A/C compressor, the belt goes up to the Idler Pulley (a smooth, non-driven pulley typically positioned above the A/C compressor, helping to guide the belt).
4. From the idler pulley, the belt then travels horizontally to the left to the Alternator Pulley (located on the upper passenger side).
5. After the alternator, the belt moves down to the Power Steering Pump Pulley (often located below the alternator).
6. From the power steering pump, the belt continues down to the Water Pump Pulley (usually found near the center of the engine, often above the crankshaft).
7. Finally, the belt wraps under the Automatic Tensioner Pulley (a spring-loaded pulley that maintains proper belt tension, usually located on the driver's side, below the power steering pump).
8. The belt then returns to the crankshaft pulley, completing the circuit.

Note: *This routing is typical for the 2.5L H4 engine. While most Foresters of this generation use this setup, always confirm against your specific vehicle and engine configuration using the photo you took.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2018 Subaru Forester requires a few basic tools and a bit of patience. The key is to release the tension on the automatic tensioner.

1. Safety First: Ensure the engine is cool and the vehicle is off. For added safety, disconnect the negative terminal of your battery.
2. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square opening, typically 3/8" or 1/2".
3. Release Tension: Insert a serpentine belt tool or a long 3/8" drive breaker bar / ratchet into the square opening of the tensioner. Slowly rotate the tensioner counter-clockwise (or as indicated by an arrow on the tensioner body) to relieve the belt tension. This will allow you to slip the old belt off the pulleys.
4. Remove Old Belt: Once tension is released, carefully remove the old belt from all pulleys, making sure to note the routing if you didn't take a photo.
5. Install New Belt: Route the new belt around all pulleys except the idler or a smooth pulley that