2017 Mercedes-Benz Sprinter Serpentine Belt: Routing, Replacement, and Part Numbers

Quick Answer

For your 2017 Mercedes-Benz Sprinter, assuming the 3.0L V6 OM642 Diesel engine (most common for this model year):

• Belt Length: Approximately 2390 mm (94.1 inches)
• Rib Count: 6-rib
• OEM Belt PN: Mercedes-Benz A0029930896
• Aftermarket Cross-references:
  • Gates K060941
  • Dayco 5060940
  • Continental Elite 4060940
• Auto-Tensioner PN: Mercedes-Benz A6422000270 (consult your VIN for exact fitment, as variations exist)
• Idler Pulley PN: Mercedes-Benz A6422020019 (check VIN for exact fitment)

Belt Routing (3.0L V6 OM642 Diesel)

Before you begin any work, always take a clear photograph of your existing serpentine belt routing. This will serve as an invaluable reference during reinstallation.

The serpentine belt on your 2017 Mercedes-Benz Sprinter 3.0L V6 diesel engine follows a specific path to drive various accessories. Here's a step-by-step description:

1. Crankshaft Pulley (Bottom Center): The belt originates from and drives the main crankshaft pulley, which is the largest pulley typically located at the bottom center of the engine.
2. A/C Compressor (Lower Right): From the crankshaft, the belt typically goes to the A/C compressor, which is often located on the lower right side of the engine (when looking from the front of the vehicle).
3. Idler Pulley (Upper Right/Middle): After the A/C compressor, the belt may pass over an idler pulley, which helps guide the belt and maintain proper tension. This idler could be positioned higher up or more towards the center.
4. Alternator (Upper Left): Next, the belt typically routes to the alternator, which generates electrical power. On the Sprinter, the alternator is usually located on the upper left side of the engine.
5. Power Steering Pump (Middle Left): From the alternator, the belt often wraps around the power steering pump pulley, which assists in steering.
6. Water Pump (Middle Top): The belt will then go to the water pump, crucial for engine cooling, usually positioned towards the top or middle of the engine.
7. Automatic Tensioner (Lower Left/Middle): Finally, the belt will route around the automatic tensioner pulley. This spring-loaded pulley applies constant tension to the belt, ensuring proper grip and preventing slippage.

Remember, visually trace your specific belt before removal as minor variations can occur.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your Sprinter requires a few specific tools and a careful approach:

1. Safety First: Ensure the engine is cool and the vehicle is securely parked with the engine off and parking brake engaged. You may want to disconnect the negative battery terminal as an extra precaution.
2. Locate the Tensioner: Identify the automatic belt tensioner. It typically has a square hole (often 3/8-inch or 1/2-inch drive) designed for a serpentine belt tool or a breaker bar.
3. Relieve Tension: Insert a serpentine belt tool or a appropriate-sized breaker bar into the square hole on the tensioner. Rotate the tensioner clockwise (or counter-clockwise, depending on the design – observe the direction it needs to move to loosen the belt) to relieve the tension on the belt. Hold it in this position.
4. Remove the Old Belt: While holding the tensioner open, carefully slip the old belt off one or more pulleys until it is free. Once loose, slowly release the tensioner.
5. Compare Belts: Before installing the new belt, compare it side-by-side with the old belt to ensure they are the same length and rib count.
6. Route the New Belt: Following your photograph and the routing description above, carefully route the new belt around all the pulleys except for the automatic tensioner or an easily accessible idler pulley.
7. Tension and Install: Once again, use your serpentine belt tool or breaker bar to relieve the tensioner. Slip the new belt over the final pulley. Double-check that all ribs on the belt are correctly seated in all the pulley grooves.
8. Verify Routing: Slowly release the tensioner and allow it to apply tension to the new belt. Give the engine a quick visual inspection to ensure the belt is properly seated on all pulleys and that the tensioner is operating correctly. Start the engine briefly (if safe) and listen for any unusual noises.

Replacement Interval

Mercedes-Benz generally recommends inspecting the serpentine belt at every service interval (typically every 10,000-20,000 miles or annually). While there isn't a rigid replacement mileage for every belt, a good proactive approach for the 3.0L V6 Sprinter is to consider replacement between 60,000 and 100,000 miles, or every 5-7 years, whichever comes first. However, always prioritize the condition of the belt over strict mileage.

If you notice any of the signs of a failing belt or tensioner mentioned below, prompt replacement is advised, regardless of mileage.

Signs of a Failing Belt or Tensioner

A failing serpentine belt or tensioner can lead to a breakdown and loss of critical systems. Be aware of these warning signs:

Signs of a Failing Belt:

• Visible Cracks or Fraying: Small cracks perpendicular to the belt's length, fraying edges, or chunking (missing pieces) are clear indicators that the belt needs replacement.
• Glazed or Shiny Appearance: The ribbed side of the belt should appear dull and clean. A shiny or glazed appearance indicates wear and potential slippage.
• Squealing or Chirping Noises: These noises, especially on startup or when turning the steering wheel, often point to a slipping belt. This can be due to wear or incorrect tension.
• Rib Damage: Look for missing ribs or signs of damage to the rib section.

Signs of a Failing Tensioner:

• Squealing or Chirping Noises: While a worn belt can cause this, a failing tensioner that isn't providing adequate tension will also lead to belt slippage and noise.
• Belt Walk: The belt may appear to "walk" or move back and forth on the pulleys instead of running straight.
• Excessive Vibrations: A bad tensioner can cause the belt to vibrate excessively.
• Misalignment: The tensioner pulley itself might be misaligned or wobbly when the engine is running (exercise extreme caution when inspecting).
• Loss of Tension: If the tensioner arm doesn't spring back forcefully or sits at the extreme end of its travel, it may no longer be providing proper tension.

Regular inspection is key to catching these issues early and preventing unexpected vehicle downtime.

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