2020 Mercedes-Benz Metris Serpentine Belt Routing & Length

Mercedes-Benz Metris vans are workhorses, and keeping them running requires diligent maintenance. The serpentine belt is a critical component that drives all the engine's accessories. This guide covers the serpentine belt system for the 2020 Mercedes-Benz Metris, which is equipped with the 2.0L M274 gasoline engine.

Quick Answer

• Belt Length: Approximately 2215 mm (87.2 inches)
• Rib Count: 6-rib
• OEM Belt Part Number: Mercedes-Benz A0039937296
• Aftermarket Cross-References: Gates K060872, Continental 6K2215, Dayco 5060870
• Auto-Tensioner Part Number: Mercedes-Benz A2742000470
• Idler Pulley Part Number: Mercedes-Benz A2742020019

Belt Routing

Properly routing the serpentine belt is crucial for the operation of your engine's accessories. An incorrectly routed belt can cause components to spin in the wrong direction (or not at all), leading to immediate issues with overheating, loss of power steering, and a dead battery. It can also cause the belt to be thrown off the pulleys, potentially damaging other components in the engine bay.

Before you remove the old belt, take several clear photographs of the existing routing from different angles. This will be your best guide for installing the new belt.

The belt path on the 2020 Metris with the 2.0L engine is as follows:

1. The belt starts at the main Crankshaft Pulley at the bottom of the engine.
2. From the Crankshaft Pulley, it moves up and to the right, wrapping around the A/C Compressor pulley.
3. It then goes up to the smooth side of the Idler Pulley.
4. From the Idler Pulley, it travels across to the Alternator pulley.
5. Next, it goes down and wraps around the Power Steering Pump pulley.
6. It continues to the Water Pump pulley.
7. Finally, it routes around the Tensioner pulley, which maintains the correct pressure on the belt.

Double-check that all ribs on the belt are sitting correctly in the grooves of each grooved pulley before starting the engine.

How to Replace the Serpentine Belt

Replacing the serpentine belt on a Metris is a manageable task for an experienced DIYer. The primary tool you will need is a serpentine belt tool or a long-handled 3/8" drive breaker bar or ratchet.

1. Locate the Tensioner: The automatic belt tensioner is the component with a pulley that is not bolted in a fixed position. It is spring-loaded to keep tension on the belt. Look for a 3/8" square hole or a hex-shaped lug on the body of the tensioner.
2. Release Tension: Insert your breaker bar or serpentine belt tool into the designated spot on the tensioner. Rotate the tensioner to release the pressure on the belt. This will require some force.
3. Remove Old Belt: While holding the tensioner in the released position, slip the old belt off one of the smooth pulleys, like the idler pulley. Once the belt is free, slowly release the tensioner back to its resting position.
4. Route New Belt: Carefully route the new belt according to your photos or the path described above, leaving the last, most accessible smooth pulley for the end.
5. Install New Belt: Rotate the tensioner again. With the tension released, slip the new belt over the final pulley. Ensure the belt is properly seated in the grooves of every pulley.
6. Final Check: Slowly release the tensioner, allowing it to apply pressure to the new belt. Visually inspect the entire path one last time to confirm correct routing and seating. Start the engine for a few seconds to ensure everything runs smoothly.

Replacement Interval

Mercedes-Benz recommends inspecting the serpentine belt at every scheduled service (typically every 10,000 miles). As a general rule, the serpentine belt should be replaced every 60,000 to 90,000 miles, or every 6-8 years, regardless of mileage. Environmental factors and driving habits can affect the belt's lifespan. Replace it sooner if you notice any signs of wear.

Signs of a Failing Belt or Tensioner

Listen to your vehicle; it will often tell you when something is wrong. Pay attention to these signs:

• Squealing Noises: A high-pitched squeal, especially on startup or when the A/C is turned on, is the most common sign of a worn or loose belt.
• Visible Wear: Inspect the belt for cracks, fraying, glazing on the surface, or missing chunks from the ribbed area. More than 3-4 cracks per inch in the ribs indicates the belt needs immediate replacement.
• Tensioner Noise: A rumbling, grinding, or chirping sound coming from the tensioner area points to a failing bearing in the tensioner pulley.
• Excessive Vibration: If you see the belt vibrating or "bouncing" excessively while the engine is running, it's often a sign that the tensioner is weak and no longer able to maintain adequate pressure.

Addressing these issues promptly can prevent a breakdown and save you from the cost of more extensive repairs that can result from a failed belt.

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