2018 Ram 2500 Serpentine Belt Guide

Quick Answer

• Belt Length & Rib Count: 103.5 inches (2629mm), 8-rib
• OEM Belt Part Number: Mopar 68273334AA
• Aftermarket Belt Cross-References: Gates K081035, Dayco 5081035, Continental 4081035
• Automatic Tensioner Part Number: Mopar 68273333AA
• Idler Pulley Part Number: Mopar 04861277AB

Belt Routing

Before you begin, always take a clear photograph of the current serpentine belt's routing. This will be an invaluable reference.

The belt winds its way around the engine accessories in a specific order. Following the path from the main crankshaft pulley, the routing is as follows:

1. Crankshaft Pulley (the largest pulley at the bottom)
2. → Air Conditioning (A/C) Compressor
3. → Idler Pulley
4. → Alternator
5. → Power Steering Pump
6. → Water Pump
7. → Tensioner (before returning to the Crankshaft Pulley)

How to Replace the Serpentine Belt

To replace the belt, you will need a serpentine belt tool or a long-handled 3/8" drive breaker bar. The automatic tensioner is spring-loaded and has a 3/8" square hole designed for this tool.

1. Insert the 3/8" drive end of your tool into the square hole on the body of the tensioner.
2. Rotate the tensioner to release the tension on the belt. You will feel the spring resist you.
3. While holding the tensioner in the released position, carefully slip the belt off one of the smooth pulleys, like the idler or water pump pulley.
4. Slowly release the tensioner.
5. Remove the old belt from the remaining pulleys.
6. Using your photo and the routing diagram above for reference, begin to route the new belt, leaving a smooth pulley for last.
7. Once the belt is routed correctly on all grooved pulleys, use your tool to release the tensioner again and slide the belt over the final smooth pulley.
8. Double-check that the belt is correctly seated in all pulley grooves before starting the engine.

Replacement Interval

For the 2018 Ram 2500 with the 6.7L Cummins, it is recommended to inspect the serpentine belt at every oil change and consider replacement between 60,000 and 100,000 miles. Driving in harsh conditions (extreme heat, dusty environments) may require earlier replacement.

Signs of a Failing Belt or Tensioner

• Squealing or Chirping Noises: This is often the first sign of a worn or glazed belt, especially on cold starts or during high-load situations (like running the A/C).
• Visible Wear: Look for cracks, fraying, missing ribs, or shiny, glazed spots on the belt.
• Tensioner Pulley Noise: A grinding or rumbling noise from the tensioner pulley indicates a failing bearing.
• Tensioner Arm Fluctuation: If you see the tensioner arm bouncing or vibrating excessively while the engine is running, the internal spring is weak and it's time for a replacement.

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