2020 Subaru Forester: Serpentine Belt Replacement Guide

Quick Answer: 2020 Forester Serpentine Belt Part Numbers

For the 2020 Subaru Forester, which is equipped with the 2.5L FB25 direct-injection engine, here are the key components for a serpentine belt service. Always verify part numbers with your VIN at a Subaru dealership or trusted parts supplier before ordering.

• Serpentine Belt Length & Rib Count: 2205mm to 2210mm, 6-rib
• OEM Subaru Belt Part Number: 809221130
• Aftermarket Belt Cross-References:
  • Gates: K060868
  • Dayco: 5060870
  • Continental: 4060870
• OEM Auto-Tensioner Assembly Part Number: 23769AA05A
• OEM Idler Pulley Part Number: 23770AA10A

Belt Routing

The 2020 Subaru Forester uses a single serpentine belt to drive all its accessories off the main crankshaft pulley. Unlike older vehicles, it uses electric power steering (EPS), so there is no hydraulic power steering pump in the belt loop.

Before you remove the old belt, it is critical to photograph the existing belt path from a few different angles. This will be your best guide for routing the new belt correctly. A misplaced belt can jump off the pulleys or fail to turn critical components like the water pump and alternator, leading to overheating or a dead battery.

The belt path is as follows:

1. Starts at the Crankshaft Pulley (the large, lowest pulley).
2. Wraps up and around the Air Conditioning Compressor pulley (passenger side).
3. Goes down and around the smooth Idler Pulley.
4. Travels up and over the Alternator pulley (top, center).
5. Comes down around the smooth Water Pump pulley.
6. Finally, loops under the spring-loaded Tensioner Pulley before returning to the crankshaft.

How to Replace the Serpentine Belt

Replacing the serpentine belt on a 2.5L Forester is a straightforward task for a DIYer with basic tools. The key is releasing the belt tension.

Tool Required: You will need a serpentine belt tool with a long handle or a 3/8" drive breaker bar. The tensioner pulley bolt is typically a 14mm hex head.

1. Safety First: Ensure the vehicle is parked on a level surface with the engine off and cool.
2. Locate the Tensioner: The automatic belt tensioner is located between the water pump and the crankshaft pulley. It consists of an arm with a smooth pulley on the end. You will see a 14mm bolt head on the front of the pulley assembly.
3. Release Tension: Place your 14mm socket and long-handled breaker bar (or serpentine belt tool) on this bolt head. Rotate the tensioner clockwise (towards the driver's side). You will feel it move against spring pressure. This movement loosens the belt.
4. Remove the Old Belt: While holding the tensioner in the released position, use your other hand to slip the belt off a smooth, accessible pulley, like the idler or water pump pulley. Once it's off one pulley, you can release the tensioner and remove the belt completely.
5. Install the New Belt: Route the new belt around the pulleys according to the path you photographed earlier, leaving a smooth pulley for last. Double-check that the ribbed side of the belt is properly seated in the grooves of all ribbed pulleys (Crank, A/C, Alternator).
6. Apply Tension: Rotate the tensioner clockwise again, and use the created slack to slip the belt over the final smooth pulley. Slowly and carefully release the tensioner, ensuring the belt stays seated correctly on all pulleys.
7. Final Check: Visually inspect the entire belt path to confirm it is routed correctly and seated properly. Start the engine for a few seconds to ensure the belt runs true, then shut it off and re-inspect.

Replacement Interval

Subaru recommends inspecting the serpentine belt at regular service intervals (every 30,000 miles) and replacing it as needed. There is no strict mileage-based replacement mandate, but most belts last between 60,000 and 100,000 miles. Given the critical role of the belt in operating the alternator and water pump, it's wise to replace it proactively if it shows any signs of wear.

Signs of a Failing Belt or Tensioner

Your belt and its related components will give you warning signs before a complete failure. Listen and look for:

• Squealing or Chirping Noises: This is the most common sign. A high-pitched squeal on startup, during acceleration, or when the A/C is turned on often points to a loose, glazed, or worn belt. A persistent "chirp-chirp-chirp" at idle often indicates a failing bearing in the tensioner or idler pulley.
• Visible Wear: Inspect the belt for cracks, fraying, missing ribs, or a "glazed" (shiny) appearance on the smooth side. Any visible damage warrants immediate replacement.
• Tensioner Pulley Wobble: With the engine running, watch the tensioner pulley. It should run smooth and true. Any noticeable wobble indicates a failing bearing.
• Tensioner Arm Movement: The tensioner arm itself should remain relatively steady while the engine is idling. If it is vibrating or jumping erratically, the internal spring mechanism is likely worn out and the entire tensioner assembly needs to be replaced.

Performing a serpentine belt service is a manageable and rewarding maintenance task. If you run into trouble or would prefer a professional handle the job, you can always find a trusted shop on Repairius.