2020 Toyota Highlander Serpentine Belt Routing & Replacement

Quick Answer

• Belt Length & Rib Count: 7PK1935 (7-rib, 1935mm effective length)
• OEM Belt PN: Toyota 90916-A2027
• Aftermarket Cross-references:
  • Gates K070762 (or K070762RPM for heavy-duty)
  • Dayco 5070760
  • Continental Elite 4070762
• Auto-Tensioner PN: Toyota 16620-0P030 (often replaced as an assembly with pulley)
• Idler Pulley PN: Toyota 16603-0P030 (note: some models might have more than one idler; verify for your specific engine)

Belt Routing Description

Before you even think about removing the old belt, take several clear photos of its current routing path! This is the single most important tip for a smooth replacement. The 2020 Toyota Highlander typically uses a serpentine belt that drives all major accessories. Here's a common routing path for the 3.5L V6 engine:

1. Crankshaft Pulley (Bottom Center): The belt starts at the largest pulley, which is the crankshaft pulley at the very bottom center of the engine. This is the driving pulley.
2. A/C Compressor (Bottom Passenger Side): From the crankshaft pulley, the belt typically goes over the A/C compressor pulley, which is usually located low on the passenger side of the engine.
3. Idler Pulley (Mid-Passenger Side): After the A/C compressor, the belt will often route under an idler pulley, which helps guide the belt and maintain proper tension.
4. Alternator (Upper Passenger Side): Next, the belt will typically go over the alternator pulley, usually positioned higher up on the passenger side, closer to the front.
5. Power Steering Pump (Upper Driver Side - if applicable): If your Highlander has a hydraulic power steering pump (some models might be electric and not belt-driven), the belt will route over this pulley, usually located on the upper driver's side.
6. Water Pump (Mid-Driver Side/Center): From the power steering pump (or alternator if no hydraulic PS), the belt commonly goes over the water pump pulley, which circulates coolant through the engine.
7. Automatic Tensioner (Mid-Center/Driver Side): Finally, the belt wraps under the automatic tensioner pulley, which applies constant tension to the belt, ensuring proper grip on all pulleys. The tensioner is spring-loaded and is the pulley you'll typically manipulate during removal/installation.

Keep in mind that minor variations can occur based on specific engine options or accessory configurations. Always refer to your under-hood diagram if available, or your service manual.

How to Replace the Serpentine Belt

Replacing the serpentine belt on a 2020 Toyota Highlander is a common maintenance task, usually requiring minimal specialized tools.

Tools You'll Need:

• Serpentine belt tool or a long-handled 3/8" breaker bar/ratchet.
• New serpentine belt.
• Possibly a diagram of the belt routing (though your photos will be better!).

Steps:

1. Safety First: Ensure the engine is off and cool. Disconnect the negative terminal of the battery if you feel more comfortable, though not strictly necessary for belt replacement.
2. Locate the Tensioner: Identify the automatic belt tensioner. It will have a square drive hole (usually 3/8" or 1/2") for your tool.
3. Relieve Tension: Insert your serpentine belt tool or breaker bar into the square drive hole on the tensioner. Gently push or pull (depending on the tensioner's orientation) to rotate the tensioner arm, relieving tension on the belt. You'll feel the spring resistance.
4. Remove Old Belt: While holding the tensioner in the "slack" position, slip the belt off one of the pulleys (e.g., the idler or alternator). Once it's off one pulley, you can slowly release the tensioner and remove the belt completely from all other pulleys. Compare the old belt to the new one for length and rib count to ensure you have the correct part.
5. Route New Belt: Refer to your photos and carefully route the new belt around all pulleys except the final one that will be slipped on last (often an idler or a smooth pulley that's easy to access for the final step). Ensure the ribs of the belt are properly seated in the grooves of the ribbed pulleys and that the smooth side of the belt is on any smooth idler pulleys.
6. Final Tensioning: Once the belt is mostly routed, re-insert your tool into the tensioner and once again relieve the tension. Slip the belt over the final pulley. Double-check that all ribs are perfectly aligned in their grooves on all pulleys.
7. Release Tensioner: Slowly release the tensioner tool, allowing the tensioner to apply full tension to the new belt. Remove your tool.
8. Verify Routing: Give the engine a quick visual inspection to confirm the belt is correctly seated on all pulleys and that its routing matches your original photos or diagram.

Replacement Interval

Toyota generally recommends inspecting the serpentine belt during routine maintenance. While there isn't a strict mileage-based replacement interval like there is for timing belts, a good rule of thumb is to consider replacement every 60,000 to 100,000 miles, or every 5-7 years, even if it doesn't show obvious signs of failure. However, it's crucial to replace it sooner if any of the "signs of a failing belt" below are present.

Signs of a Failing Belt or Tensioner

It's important to be vigilant for symptoms that indicate your serpentine belt or its tensioner might be nearing the end of their service life.

• Squealing or Chirping Noises: This is the most common symptom. A loose, worn, or misaligned belt will often squeal, especially on cold starts, when turning the steering wheel, or during acceleration. A failing tensioner can also cause noise.
• Cracks, Fraying, or Glazing: Visually inspect the belt. Look for cracks running across the ribs, chunks missing, frayed edges, or a smooth, shiny (glazed) appearance on the ribbed side. Any of these are strong indicators for replacement.
• Loss of Power to Accessories: Since the belt drives multiple components, a failing or broken belt will lead to a loss of power to your alternator (battery warning light), power steering (heavy steering), A/C (no cold air), and water pump (engine overheating).
• Hard Steering: If your Highlander has hydraulic power steering, a slipping or broken belt will make steering very difficult.
• Battery Warning Light: A failing belt may prevent the alternator from charging the battery, illuminating the battery warning light on your dashboard.
• Engine Overheating: If the water pump isn't being driven properly due to a slipping or broken belt, your engine can quickly overheat.
• Tensioner Play or Noise: With the engine off, try to wiggle the tensioner pulley. Excessive play or grinding noises when spinning the tensioner pulley by hand can indicate a failing tensioner or its bearing.

Replacing a worn serpentine belt and tensioner proactively can save you from being stranded and prevent further damage to your vehicle. Always opt for quality components.

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