2019 Subaru Forester Serpentine Belt Routing & Replacement

Quick Answer

• Belt Length: Approximately 82.7 inches (2100 mm)
• Rib Count: 6-rib
• OEM Belt PN: 840409 (Subaru)
• Aftermarket Cross-references:
  • Gates K060827
  • Dayco 5060827
  • Continental Elite 4060827
• Auto-Tensioner PN: 23769AA00A (Subaru)
• Idler Pulley PN: 23770AA00A (Subaru)

Belt Routing

The 2019 Subaru Forester, particularly models equipped with the 2.5L naturally aspirated engine, utilizes a single serpentine belt to drive all engine accessories. Before attempting any belt removal, it is highly recommended to take a clear photograph of the existing belt's routing path. This will serve as an invaluable guide during reinstallation.

Here’s a step-by-step text description of the routing, starting from the crankshaft pulley:

1. Crankshaft Pulley: The belt originates at the bottom, wrapping around the largest pulley – the crankshaft pulley, which powers all other accessories.
2. A/C Compressor: From the crankshaft, the belt travels upwards and to the right (when facing the front of the engine), engaging the first accessory: the air conditioning (A/C) compressor pulley.
3. Idler Pulley: After exiting the A/C compressor, the belt moves upwards to the left, passing over the smooth surface of a specified idler pulley, which helps maintain tension and proper alignment.
4. Alternator: The belt then continues upwards and to the right, wrapping around the alternator pulley, which is responsible for generating electrical power for the vehicle.
5. Power Steering Pump: Exiting the alternator, the belt traverses to the left, engaging the power steering pump pulley. Note: Some 2019 Forester models may have electric power steering, in which case this pulley may not be present or will be a different accessory.
6. Water Pump: From the power steering pump, the belt moves downwards and to the right, wrapping around the water pump pulley, which circulates coolant through the engine.
7. Tensioner Pulley: Finally, the belt courses downwards to the left, where it meets the automatic tensioner pulley. The tensioner is critical for maintaining optimal belt tension, ensuring consistent power transfer and preventing slippage.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2019 Subaru Forester is a manageable DIY task, but requires the right tools and attention to detail.

Tools You'll Need:

• Serpentine belt tool or a 3/8-inch drive breaker bar/ratchet (for the tensioner)
• New serpentine belt
• Socket set (potentially for removing covers or gaining access)

Replacement Steps:

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 drive hole (usually 3/8-inch) for your tool.
3. Relieve Tension: Insert your serpentine belt tool or breaker bar into the square hole on the tensioner. Rotate the tensioner counter-clockwise (or clockwise, depending on the engine configuration) to release the tension on the belt. Hold it in this position.
4. Remove Old Belt: While holding the tensioner, carefully slip the old belt off one or more pulleys. Once loose, you can release the tensioner and remove the belt entirely.
5. Compare Belts: Before installing the new belt, compare its length and rib count to the old belt to ensure you have the correct part.
6. Route New Belt: Following your previously taken photograph or the routing description above, carefully route the new belt around all the pulleys, leaving the tensioner pulley for last or a pulley that offers easy last-step installation.
7. Apply Tension: Again, use your tool to rotate the tensioner to its loosened position. Slip the new belt over the final pulley.
8. Verify Routing: Once the belt is fully installed, slowly release the tensioner and double-check that the belt is correctly seated in all pulley grooves. Ensure there are no twists or misalignments.
9. Reconnect Battery & Test: Reconnect the negative battery terminal. Start the engine and let it run for a minute, observing the belt for proper operation and listening for any unusual noises.

Replacement Interval

Subaru typically recommends inspecting the serpentine belt during regular service intervals, usually every 30,000 miles or 30 months. Replacement is generally recommended between 60,000 to 100,000 miles, or sooner if signs of wear are observed. However, environmental factors like extreme temperatures, dust, and oil contamination can accelerate wear, necessitating earlier replacement. Always refer to your vehicle-specific owner's manual for the most accurate and up-to-date maintenance schedule.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to significant issues, including loss of power steering, A/C, and charging system operation, or even engine overheating if the water pump stops turning. Be vigilant for the following symptoms:

• Squealing or Chirping Noises: This is one of the most common indicators, especially on cold starts, during acceleration, or when turning the steering wheel. It often points to a worn or loose belt, or a failing pulley bearing.
• Cracks, Fraying, or Glazing: Visually inspect the belt. Deep cracks, missing ribs, fraying edges, or a smooth, shiny (glazed) appearance on the ribbed side indicate severe wear and a need for immediate replacement.
• Loss of Power Steering: If your steering becomes suddenly difficult to turn, especially at low speeds, it could mean the belt driving your power steering pump has slipped or broken.
• Battery Warning Light: A lit battery warning light could indicate that the alternator is not being driven effectively by the serpentine belt, leading to a loss of charging.
• A/C Not Working: If your air conditioning stops blowing cold air, and other electrical systems are functioning, the belt driving the A/C compressor might be at fault.
• Engine Overheating: A broken or slipping belt can prevent the water pump from circulating coolant, leading to a rapidly overheating engine.
• Wobbling or Misaligned Pulleys: During engine operation, observe the pulleys (from a safe distance). Any noticeable wobble or misalignment of the tensioner or idler pulleys suggests a failing bearing or tensioner unit.
• Clicking or Grinding Noises from Tensioner: A failing tensioner often makes metallic clicking, grinding, or rattling noises, indicating internal wear or a seized bearing.

Promptly addressing these signs will prevent further damage and ensure the reliable operation of your Subaru Forester.

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