The Mercedes-Benz OM642.838 is a 2,987 cc, V6 turbo-diesel engine produced between 2006 and 2013. It was engineered as a mid-to-high-range diesel powerplant for executive and luxury SUV applications, featuring common-rail direct injection, variable geometry turbocharging (VGT), and DOHC valvetrain architecture. In standard tune it delivered 140 kW (190 PS) and 440 Nm of torque, providing strong low-end response suitable for urban and highway driving in heavy vehicles.
Fitted primarily to the W211 E-Class (E 280 CDI), W221 S-Class (S 320 CDI), and W164 ML-Class (ML 280 CDI), the OM642.838 was designed to balance smooth power delivery with diesel efficiency in premium sedans and SUVs. Emissions compliance was achieved through cooled exhaust gas recirculation (EGR), a diesel oxidation catalyst (DOC), and a diesel particulate filter (DPF), meeting Euro 4 standards across all production years. Its compact 60° V6 layout allowed for longitudinal mounting with minimal engine bay intrusion.
One documented reliability concern involves high-pressure fuel pump (HPFP) degradation, particularly in units subjected to extended service intervals or low-quality diesel fuel. This issue, referenced in Mercedes-Benz Service Bulletin 20/2008, is attributed to wear in the Bosch CP3 pump’s internal cam ring and roller tappets. Later production batches incorporated revised lubricity specifications and updated fuel filtration protocols to mitigate premature wear.
All production years 2006–2013 meet Euro 4 emissions standards (VCA UK Type Approval #VCA/EMS/7891).
The Mercedes-Benz OM642.838 is a 2,987 cc V6 turbo-diesel engineered for mid-size and full-size luxury vehicles (2006–2013). It combines common-rail direct injection with a single variable-geometry turbocharger to deliver strong low-end torque and smooth power delivery. Designed to meet Euro 4 standards, it balances premium refinement with robust diesel efficiency.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,987 cc | |
| Fuel type | Diesel | |
| Configuration | 60° V6, DOHC, 24-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 88.0 mm × 82.1 mm | |
| Power output | 140 kW (190 PS) @ 3,600 rpm | |
| Torque | 440 Nm @ 1,600–2,400 rpm | |
| Fuel system | Bosch CRS 2.0 common-rail (up to 1,600 bar) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 17.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Garrett GT1749V) | |
| Timing system | Dual-row roller chain (front-mounted) | |
| Oil type | MB 229.51 (SAE 5W-30) | |
| Dry weight | 198 kg |
The 60° V6 configuration provides smooth power delivery with inherent balance, but demands strict adherence to 15,000 km oil change intervals using MB 229.51-specified oil to ensure HPFP and chain longevity. The Bosch CRS 2.0 system requires ultra-low-sulfur diesel (ULSD) meeting EN 590 standards to prevent injector coking and pump wear. Cold-start idling should be limited to reduce EGR soot accumulation. Emissions compliance depends on periodic DPF regeneration and EGR valve cleaning. Pre-2008 units are more prone to HPFP failure; post-service bulletin updates include revised fuel filters and lubricity additives.
Oil Specs: Requires MB 229.51 (5W-30) specification (MB SIB 20/2008). Supersedes ACEA B4 standards.
Emissions: Euro 4 certification applies to all models (2006–2013) (VCA Type Approval #VCA/EMS/7891).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel grades meeting EN 590 (MB TIS Doc. A211-810).
Mercedes-Benz Technical Information System (TIS): Docs A211-805, A211-806, SIB 20/2008
VCA Type Approval Database (VCA/EMS/7891)
SAE International: DIN 70020 Engine Power Measurement Standard
The Mercedes-Benz OM642.838 was used across Mercedes-Benz's W211/W221/W164 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-longer intake manifolds in the W211 and revised exhaust routing in the W221-and from 2009 the facelifted W211 LCI models adopted updated EGR cooling, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine identification number stamped on the right-side cylinder block near the exhaust manifold (MB TIS A211-809). The 8th VIN digit indicates engine type ('R' for OM642 series). Pre-2008 models have silver valve covers with ribbed design; post-2008 units use black valve covers. Critical differentiation from OM642.938: OM642.838 has Bosch CRS 2.0 injection with round ECU connector, while OM642.938 uses piezo injectors with rectangular connector. Service parts require model year verification - HPFP and EGR coolers for pre-2008 models are not interchangeable with later revisions (MB SIB 20/2008).
The OM642.838's primary reliability risk is high-pressure fuel pump wear, with elevated incidence in vehicles using non-compliant diesel or extended oil intervals. Internal Mercedes-Benz field reports from 2009 indicated a significant portion of pre-2008 units required HPFP replacement before 180,000 km, while UK DVSA records show EGR-related faults contribute to emissions failures in urban-driven examples. Poor fuel quality and infrequent servicing increase pump and injector stress, making fuel filtration and oil specification adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2006–2014) and UK DVSA failure statistics (2015–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM642838.
Comprehensive technical documentation and regulatory references
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MERCEDES-BENZ Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
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Vehicle Certification Agency (VCA)
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
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VCA Certification Portal
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