2021 Toyota Tacoma Serpentine Belt Guide

Quick Answer

For the 2.7L 4-Cylinder (2TR-FE Engine):

• Belt Length: 2200mm (86.6 inches)
• Rib Count: 7-rib
• OEM Belt Part Number: Toyota 90916-A2024
• Aftermarket Cross-References: Gates K070866, Dayco 5070865, Continental 4070866
• Automatic Tensioner Part Number: Toyota 16620-75030
• Idler Pulley Part Number: Toyota 16604-0P011 (Upper), Toyota 16603-0P030 (Lower)

For the 3.5L V6 (2GR-FKS Engine):

• Belt Length: 1913mm (75.3 inches)
• Rib Count: 7-rib
• OEM Belt Part Number: Toyota 90916-A2021
• Aftermarket Cross-References: Gates K070753, Dayco 5070755, Continental 4070753
• Automatic Tensioner Part Number: Toyota 16620-0P080
• Idler Pulley Part Number: Toyota 16604-0P011 (Upper), Toyota 16603-0P030 (Lower, No. 2 Idler)

Belt Routing

Before you begin, always take a clear photograph of the current serpentine belt routing with your phone. This simple step can save you a significant amount of time and frustration during reassembly. The belt winds around numerous pulleys, and a photo provides a foolproof reference.

2.7L 4-Cylinder (2TR-FE) Belt Routing

The belt path for the 2.7L engine is as follows:

1. Starts at the bottom main crankshaft pulley.
2. Wraps up and around the A/C compressor on the lower passenger side.
3. Goes down and around the idler pulley.
4. Travels up to the alternator on the upper passenger side.
5. Crosses over the front of the engine to the power steering pump.
6. Moves down to the water pump.
7. Finishes by wrapping under the automatic tensioner before returning to the crank pulley.

3.5L V6 (2GR-FKS) Belt Routing

The V6 engine follows a slightly different path:

1. Begins at the main crankshaft pulley.
2. Wraps around the A/C compressor.
3. Goes up and around the No. 2 idler pulley (lower).
4. Travels up to the alternator.
5. Crosses over to the power steering pump.
6. Goes around the water pump.
7. Loops up to the No. 1 idler pulley (upper).
8. Finally, loops down and around the automatic tensioner before returning to the crankshaft.

How to Replace the Serpentine Belt

Replacing the serpentine belt on a 2021 Tacoma is a straightforward job for a DIYer with basic tools. You will need a serpentine belt tool or a long-handled 3/8" or 1/2" drive breaker bar with a 14mm socket to release the belt tension.

1. Locate the Automatic Tensioner: Find the automatic tensioner pulley. It has a 14mm cast hex nut on the front of the pulley body for you to attach your tool.
2. Release Tension: Using your serpentine belt tool or breaker bar, rotate the tensioner clockwise (towards the passenger side). This will swing the pulley down, releasing tension on the belt.
3. Remove the Old Belt: While holding the tensioner, carefully slip the belt off one of the smooth, accessible pulleys like the idler or water pump.
4. Route the New Belt: Following your reference photograph and the path described above, carefully route the new belt around all pulleys except for one smooth, easily accessible pulley (like the idler).
5. Install the New Belt: Release the tensioner again by rotating it clockwise. Slide the belt over the final pulley. Double-check that the belt is correctly seated in the ribbed grooves of every pulley.
6. Final Check: Start the engine and let it run for about 15 seconds to ensure the belt is tracking correctly and not making any unusual noises.

Replacement Interval

Toyota does not specify a strict replacement interval for the serpentine belt on the 2021 Tacoma. Instead, it is designated as an "inspect and replace as needed" item during scheduled maintenance, typically starting around 60,000 miles.

However, as a general rule, it's wise to consider replacing the belt every 60,000 to 90,000 miles to prevent an unexpected failure. The automatic tensioner and idler pulleys should be inspected at the same time and replaced if they show signs of wear.

Signs of a Failing Belt or Tensioner

Look out for these common symptoms that indicate your serpentine belt system needs attention:

• Squealing or Chirping Noises: This is the most common sign, especially on cold starts or during sharp turns. It indicates the belt is slipping.
• Visible Wear: Inspect the belt for cracks, fraying, glazing (shiny spots), or missing ribs. Any of these mean the belt is due for replacement.
• Grinding or Rumbling from Pulleys: A bad bearing in the tensioner or an idler pulley will often make a grinding or rumbling noise that changes with engine RPM.
• Dimming Lights or "ALT" Light: If the belt is slipping on the alternator pulley, it can cause a drop in electrical output.
• Overheating: If the belt can't properly turn the water pump, the engine may begin to overheat.
• Stiff Steering: Reduced power steering assist can occur if the belt slips on the power steering pump pulley.

If you're not comfortable performing this service yourself, let Repairius connect you with a qualified local expert.

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