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

Quick Answer

For the 2017 Mercedes-Benz Metris with the 2.0L M274 engine, here are some quick facts regarding your serpentine belt:

• Belt Length: Approximately 2100mm (82.7 inches)
• Rib Count: 6-rib
• OEM Belt Part Number: Mercedes-Benz A0039930796
• Aftermarket Cross-References (confirm fitment):
  • Gates K060827 (or K060827RPM for heavy duty)
  • Dayco 5060827
  • Continental Elite 4060827
• Auto-Tensioner Part Number: Mercedes-Benz A2742000570
• Idler Pulley Part Number: Mercedes-Benz A2742020000

Belt Routing (2.0L M274 Engine)

The serpentine belt on your 2017 Mercedes-Benz Metris follows a specific path to drive various accessories. Before you begin any work, always take a photograph of your current belt routing! This will serve as an invaluable reference during reinstallation.

Here's a step-by-step description of the belt routing:

1. Begin at the Crankshaft Pulley (the largest pulley, typically at the bottom center of the engine).
2. From the crankshaft pulley, the belt typically travels up and to the left to the A/C Compressor Pulley.
3. From the A/C compressor, the belt routes up to an Idler Pulley (a smooth pulley that guides the belt).
4. After the idler pulley, the belt goes down and to the right to the Alternator Pulley.
5. From the alternator, the belt continues down to the Power Steering Pump Pulley.
6. The belt then travels up and to the left to the Water Pump Pulley.
7. Finally, the belt makes its way down to the Automatic Tensioner Pulley, which maintains proper belt tension. The belt will then loop back to the crankshaft pulley, completing the path.

Please note: Some variations may exist based on specific vehicle options. Always refer to your vehicle's service manual or the diagram under the hood if one is present.

How to Replace the Serpentine Belt

Replacing the serpentine belt on your Metris is a moderately challenging DIY task. Here's a general overview of the process:

1. Safety First: Ensure the engine is cool and the vehicle is securely parked with the parking brake engaged.
2. Locate the Tensioner: Identify the automatic tensioner pulley. It will have a square opening (often 3/8-inch or 1/2-inch) or a hex bolt in the center.
3. Relieve Tension: Insert a serpentine belt tool or a 3/8-inch (or appropriate size) breaker bar into the square opening of the tensioner. Slowly rotate the tensioner to relieve tension on the belt. Be careful not to over-rotate or damage the tensioner.
4. Remove Old Belt: While holding the tensioner in the relieved position, carefully slip the old belt off one of the pulleys (usually the idler or a smooth pulley is easiest).
5. Inspect Pulleys: With the belt off, inspect all pulleys for any signs of wear, wobbling, or excessive noise. Replace any worn idler pulleys or tensioners as needed.
6. Route New Belt: Using your photograph and the routing diagram above as a guide, carefully route the new belt around all pulleys, leaving the tensioner pulley or an easily accessible smooth pulley for last.
7. Final Tensioning: Once the belt is mostly in place, use your serpentine belt tool/breaker bar to relieve tension on the tensioner again and slip the new belt onto the final pulley. Slowly release the tensioner, ensuring the belt is properly seated in all grooves.
8. Double-Check: Before starting the engine, visually inspect the entire belt path to confirm it's correctly seated on all pulleys.

Replacement Interval

Mercedes-Benz generally recommends inspecting the serpentine belt at every service interval and replacing it proactively if signs of wear are observed. While there isn't a universally specified mileage for replacement, a good rule of thumb is to consider replacement every 60,000 to 100,000 miles, or every 5-7 years, whichever comes first. However, driving conditions and climate can affect its lifespan. Regular visual inspection is key.

Signs of a Failing Belt or Tensioner

Ignoring a failing serpentine belt or tensioner can lead to a breakdown, as it drives essential components like the alternator, power steering, and A/C compressor. Watch out for these warning signs:

• Squealing or Chirping Noise: This is one of the most common indicators of a worn or misaligned belt, or a failing tensioner/pulley bearing, especially upon cold start or during acceleration.
• Cracks, Fraying, or Glazing: Visually inspect the belt for these signs of wear. Glazed (shiny) belts indicate a loss of grip.
• Loss of Power Steering: If your power steering suddenly becomes difficult, the belt may have slipped or broken.
• Overheating Engine: A broken belt will stop the water pump from circulating coolant, leading to engine overheating.
• Battery Warning Light: If the alternator isn't turning, your battery won't charge, illuminating the battery warning light on your dashboard.
• A/C Not Working: The A/C compressor relies on the serpentine belt. If the belt is broken, your A/C will stop blowing cold air.
• Belt Wobble: Excessive wobble or vibration of the tensioner pulley can indicate a failing tensioner.
• Misalignment: Check if the belt is seated correctly in the grooves of all pulleys. Misalignment can cause premature wear.

If you notice any of these symptoms, it's crucial to address the issue promptly to prevent further damage or a breakdown.

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