Mercedes Sprinter Serpentine Belt Tensioner Assembly – OEM | OM642 3.0L V6 | #6422001370

DESCRIPTION:

A worn serpentine belt tensioner is one of those failures that sneaks up fast. When the spring weakens or the bearing starts to go, belt tension becomes inconsistent — and an improperly tensioned belt can slip, squeal, or snap, taking your alternator, power steering pump, water pump, and A/C compressor with it. This OEM replacement tensioner assembly restores correct, consistent belt tension and protects the entire accessory drive system.

What This Part Does

The belt tensioner uses a spring-loaded arm and pulley to maintain constant, precise tension on the serpentine belt as it drives the engine's accessory components. As the belt stretches over time and temperature cycling causes components to shift, the tensioner compensates automatically. When the internal spring weakens or the bearing roller fails, that compensation disappears — and belt slippage or failure follows.

Common Symptoms of a Failing Tensioner

• Squealing or chirping noise from the front of the engine
• Visible belt wobble or excessive slack
• Accessory warning lights — battery, power steering, or A/C
• Tensioner arm that moves freely with no spring resistance

When to Replace It

Replace the tensioner whenever you're replacing the serpentine belt — it's a logical pairing since both wear together. Also replace if you notice any of the symptoms above or if the tensioner pulley bearing feels rough when spun by hand.

Fitment

• 2007–2009 Dodge Sprinter 2500/3500 – 3.0L V6 Diesel (OM642)
• 2007–2017 Freightliner Sprinter 2500/3500 – 3.0L V6 Diesel (OM642)
• 2010–2022 Mercedes-Benz Sprinter 2500 – 3.0L V6 Diesel (OM642)
• 2010–2022 Mercedes-Benz Sprinter 3500 – 3.0L V6 Diesel (OM642)
• 2018–2022 Mercedes-Benz Sprinter 3500XD – 3.0L V6 Diesel (OM642)

Note: Not compatible with 2007 CDI-designated R, ML, or GL vehicles. Always verify your VIN before ordering. Contact us and we'll confirm fitment before you buy.

Part Numbers

• Mercedes OEM: 6422001370 / A6422001370 / 642-200-13-70
• Cross Reference: 68040206AA, 5175588AA, 534018310, FT40183