2021 Toyota Highlander Serpentine Belt Reference

Quick Answer

• Belt Length: Varies by engine option (see below)
• Rib Count: 6-Rib
• OEM Belt PN (3.5L V6): 90916-02796
• Aftermarket Cross-Reference (3.5L V6): Gates K060858, Dayco 5060858, Continental 4060858
• OEM Auto-Tensioner PN (3.5L V6): 16620-0P030
• OEM Idler Pulley PN (3.5L V6): 16603-0P030

Belt Routing (3.5L V6 Engine)

Before you begin any work, always take a clear picture of your current belt routing! This will be your best visual guide for reinstallation. The 2021 Toyota Highlander with the 3.5L V6 engine utilizes a common serpentine belt routing.

Starting from the crankshaft pulley (the largest pulley at the bottom):

1. From the crankshaft pulley, the belt travels to the A/C compressor (typically on the lower passenger side).
2. From the A/C compressor, it goes up to the idler pulley (a smooth pulley that guides the belt).
3. From the idler pulley, the belt then goes to the alternator (usually on the upper driver's side).
4. Next, it wraps around the power steering pump pulley (if applicable, though many modern Highlanders have electric power steering, so this pulley may be absent or part of another accessory).
5. The belt then goes to the water pump pulley (often located in the center or slightly offset).
6. Finally, it wraps around the automatic belt tensioner (usually a spring-loaded pulley that maintains belt tension) before returning to the crankshaft pulley.

Note: If your Highlander is equipped with the 2.5L Hybrid engine, the belt routing and part numbers will differ. Consult a service manual or parts catalog specific to your vehicle's engine.

How to Replace the Serpentine Belt

Replacing a serpentine belt is a job many DIYers can tackle with the right tools and a little patience.

1. Gather your tools: You'll need a serpentine belt tool or a long 3/8" drive breaker bar, a new serpentine belt, and potentially a socket to fit the tensioner arm (if not a square drive). Safety glasses and gloves are also recommended.
2. Locate the automatic tensioner: This will be a pulley with a square hole (for a 3/8" drive) or a bolt head that allows you to release tension.
3. Relieve belt tension: Insert your serpentine belt tool or breaker bar into the tensioner's square hole or onto the bolt. Rotate the tensioner arm to release the tension on the belt. This will allow you to slip the belt off the pulleys.
4. Remove the old belt: Once tension is relieved, carefully remove the old belt from all the pulleys, paying close attention to the routing, and referencing your photograph.
5. Install the new belt: Route the new belt around all the pulleys except the tensioner or an easily accessible smooth pulley. Use your photograph as your guide.
6. Apply tension and seat the belt: With the belt mostly in place, use your tool to relieve tension on the tensioner again. Slip the new belt over the final pulley. Slowly release the tensioner, ensuring the belt is properly seated in all the pulley grooves. Double-check all pulleys to ensure the belt is not off-track.
7. Final inspection: Start the engine briefly and listen for any unusual noises. Turn off the engine and visually inspect the belt again to ensure it's tracking correctly.

Replacement Interval

Toyota generally recommends inspecting the serpentine belt at every scheduled maintenance interval (typically every 15,000 to 30,000 miles) and replacing it if signs of wear are present. Many technicians recommend proactive replacement between 60,000 to 100,000 miles as a preventative measure, even if it appears to be in good condition. However, always refer to your vehicle's owner's manual for specific recommendations.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to a breakdown and potential damage to other components. Here are common warning signs:

• Squealing or chirping noises: This is often the most common symptom, especially during cold starts or when the accessory load changes (e.g., turning on the A/C).
• Cracks, fraying, or glazing on the belt: Visual inspection can reveal a worn belt. Small cracks across the ribs are normal with age, but deep cracks, missing chunks, or a shiny, glazed appearance on the belt surface indicate it needs replacement.
• Loose belt: If the belt appears unusually slack, the tensioner may be failing to maintain proper tension.
• Vibrations: Excessive vibrations from the belt area can indicate a failing tensioner or pulley bearing.
• Loss of power to accessories: If the belt is slipping or broken, accessories like the alternator, power steering pump, or A/C compressor may not function correctly, leading to dim lights, hard steering, or a lack of cold air.
• Indicator light: In some vehicles, a battery light or a "Check Engine" light may illuminate if the alternator isn't charging due to a slipping or broken belt.

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