2021 Ram 3500 Serpentine Belt Guide

Quick Answer

For the 6.4L HEMI V8 Gas Engine:

• Belt Length: 2492mm (98.1 inches)
• Rib Count: 8-rib
• OEM Belt Part Number: 68192237AA
• Aftermarket Cross-References: Gates K080980, Dayco 5080980, Continental 4080980
• Auto-Tensioner Part Number: 53034110AA
• Idler Pulley Part Number: 53032840AA

For the 6.7L Cummins Diesel Engine:

• Belt Length: 1920mm (75.6 inches)
• Rib Count: 8-rib
• OEM Belt Part Number: 68444723AA
• Aftermarket Cross-References: Gates K080756, Dayco 5080755, Continental 4080755
• Auto-Tensioner Part Number: 68444724AA
• Idler Pulley Part Number: 68444725AA

Belt Routing

Before you remove the old serpentine belt, it is crucial to either find the belt routing diagram sticker in the engine bay (often on the radiator support or fan shroud) or take a clear photograph of the belt's path. This will be your guide for installing the new belt.

While the exact path can vary based on engine type and accessories, a common routing for the 6.4L HEMI V8 is as follows:

1. Starting from the main crankshaft pulley at the bottom.
2. The belt travels up to the A/C compressor.
3. It then goes around the idler pulley.
4. Next, it routes to the alternator.
5. From the alternator, it goes down to the power steering pump.
6. Then, it moves to the water pump.
7. Finally, it wraps around the auto-tensioner, which maintains the belt's tension.

For the 6.7L Cummins Diesel, the routing is different due to the engine's design, but the principle remains the same. Always refer to your specific vehicle's diagram or the photo you took.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your 2021 Ram 3500 is a manageable task with the right tool. You will need a serpentine belt tool, which is a long, thin breaker bar with various socket and crowfoot attachments. In many cases, a standard 3/8" or 1/2" drive breaker bar will fit directly into the square hole on the auto-tensioner.

1. Locate the Auto-Tensioner: Find the automatic tensioner pulley. It's the one with a spring-loaded arm.
2. Release Tension: Fit your serpentine belt tool or breaker bar into the designated slot on the tensioner body. Rotate the tensioner to release the pressure on the belt. This will require some force.
3. Remove the Old Belt: While holding the tensioner in the released position, carefully slip the old belt off one of the smooth pulleys (like the idler or water pump).
4. Inspect Pulleys: Before installing the new belt, spin each pulley by hand. They should spin freely and quietly. A noisy or wobbly pulley indicates a bad bearing, and the pulley should be replaced.
5. Install the New Belt: Following the routing diagram or your photo, thread the new belt around all the pulleys, saving one of the easily accessible smooth pulleys for last.
6. Apply Tension: Release the tensioner again with your tool and slide the belt over the final pulley. Double-check that the belt is correctly seated in the grooves of every ribbed pulley. A misaligned belt will shred itself quickly.
7. Final Check: Once the belt is on, slowly release the tensioner to let it apply pressure. Start the engine and let it run for a minute to ensure the belt is tracking correctly.

Replacement Interval

For the 2021 Ram 3500, it is recommended to inspect the serpentine belt at every oil change. While modern EPDM belts are durable, they don't always show the classic signs of cracking like older neoprene belts. A general guideline for replacement is every 60,000 to 100,000 miles, or as recommended in your owner's manual. However, if you notice any signs of wear, it should be replaced immediately, regardless of mileage.

Signs of a Failing Belt or Tensioner

Be aware of these symptoms that indicate it's time for a replacement:

• Squealing or Chirping Noises: This is the most common sign of a worn or loose belt, often more noticeable on cold starts or in wet weather.
• Visible Wear: Look for cracks, fraying, glazing (shiny spots), or missing ribs on the belt.
• Tensioner Noise: A rattling or grinding noise coming from the tensioner pulley indicates a failing bearing.
• Tensioner Arm Vibration: If you see the tensioner arm bouncing or vibrating excessively while the engine is running, the spring is likely weak and the tensioner needs to be replaced.
• Accessory Malfunctions: Since the serpentine belt drives multiple components, a failing belt can cause issues like a dead battery (bad alternator rotation), overheating (bad water pump rotation), or stiff steering (bad power steering pump rotation).

If you're not comfortable performing this service yourself, we can help.

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