Mercedes Sprinter Timing Chain Tensioner – LUK | NCV3 & VS30 3.0L OM642 | #6420500311 (2007–2022)

A failed timing chain tensioner on a Sprinter OM642 allows chain slack to develop that the tensioner can no longer compensate for — producing the cold-start rattle that gets louder with each startup, and eventually allowing the chain to skip a tooth on the cam sprocket and cause catastrophic valve-to-piston contact. This is the LUK timing chain tensioner for NCV3 and VS30 Sprinters equipped with the 3.0L OM642 V6 diesel engine, a direct OEM-equivalent replacement that restores correct chain tension and eliminates tensioner-related timing chain noise.

What This Part Does

The timing chain tensioner is a hydraulic or spring-loaded mechanical assembly that pushes against the timing chain through a pivoting tensioner arm, maintaining the correct tension on the chain regardless of temperature, wear, or operating conditions. On cold startup, before oil pressure builds, the tensioner must hold the chain in position using its internal spring — the characteristic cold-start rattle is the chain slapping before oil pressure activates the hydraulic element. Once oil pressure builds, the hydraulic element takes over and maintains steady tension through the full RPM and load range. When the tensioner's internal ratchet mechanism wears, its hydraulic element loses its ability to maintain pressure, or its sealing surfaces degrade, it can no longer compensate for chain slack — and the chain begins producing noise and timing variation that only worsens.

Common Symptoms of a Failing Timing Chain Tensioner

• Timing chain rattle on cold start that takes longer than normal to clear — or doesn't clear at all
• Persistent valvetrain noise from the front of the engine after warm-up
• Timing-related fault codes or camshaft position sensor deviation codes
• Chain noise that worsens under load — a sign the tensioner is no longer maintaining pressure
• Metal particles in the oil from a tensioner that has worn internally

When to Replace

Replace whenever the timing cover is opened for timing system service, and always in conjunction with the guide rail set (6420502600). The tensioner and rails work as a system — replacing one without the other leaves a worn component that will accelerate wear on the new part. Also replace the timing chain if it has stretched beyond specification.

NCV3 & VS30 OM642 Specific — VIN Verification Required

This tensioner is for NCV3 and VS30 Sprinters equipped with the 3.0L OM642 V6 diesel engine. Always verify your engine code and VIN before ordering. Contact us and we'll confirm fitment before you buy.

Fitment

• 2007–2018 Mercedes-Benz Sprinter 2500 / 3500 – 3.0L OM642 (NCV3/W906)
• 2007–2009 Dodge Sprinter 2500 / 3500 – 3.0L OM642 (NCV3)
• 2007–2018 Freightliner Sprinter 2500 / 3500 – 3.0L OM642 (NCV3)
• 2019–2022 Mercedes-Benz Sprinter 2500 / 3500 – 3.0L OM642 (VS30/W907)

✔ Always replace with guide rail set (6420502600) for a complete timing system service
✔ Replace timing chain if stretched beyond specification at the same service

Part Numbers

• Mercedes OEM: 6420500311 / A6420500311 / 642-050-03-11
• Cross-reference: 68028728AA / ZT0183
• Manufacturer: LUK — 551018310 / 26750
• SKU: 6420500311