The Mercedes-Benz OM 642.850 is a 2,987 cc, V6 turbo-diesel engine produced between 2006 and 2013. It was engineered as a refined, high-torque powerplant for executive and luxury SUV applications, featuring common-rail direct injection, variable geometry turbocharging (VGT), and double overhead camshafts (DOHC). In standard tune, it delivered 150 kW (204 PS) and 540 Nm of torque, providing strong low-end response and smooth cruising refinement.
Fitted primarily to the W211 E-Class (E320 CDI), W221 S-Class (S320 CDI), and W164 ML-Class (ML 320 CDI), the OM 642.850 was designed for drivers seeking a balance of comfort, pulling power, and fuel efficiency. Emissions compliance was achieved through exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF), enabling Euro 4 certification across its initial production run. From 2009 onward, updated calibration allowed select models to meet Euro 5 standards.
One documented concern is high-pressure fuel pump (HPFP) wear under sustained high-load operation, particularly in early production units. This issue, referenced in Mercedes-Benz Service Information Bulletin 22/2007, was linked to fuel quality sensitivity and inadequate filtration in pre-2009 builds. From 2009 onward, an updated HPFP design and revised ECU calibration were implemented to improve long-term reliability under real-world conditions.
Production years 2006–2008 meet Euro 4 standards; 2009–2013 models comply with Euro 5 depending on market (VCA UK Type Approval #VCA/EMS/6780).
The Mercedes-Benz OM 642.850 is a 2,987 cc V6 turbo-diesel engineered for executive sedans and SUVs (2006–2013). It combines common-rail direct injection with a single variable-geometry turbocharger to deliver responsive performance and driving comfort. Designed to meet Euro 4 and later Euro 5 emissions standards, it balances efficiency with strong torque delivery.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,987 cc | |
| Fuel type | Diesel | |
| Configuration | 90° V6, DOHC, 24-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 88.0 mm × 82.1 mm | |
| Power output | 150 kW (204 PS) @ 3,800 rpm | |
| Torque | 540 Nm @ 1,600–2,400 rpm | |
| Fuel system | Bosch CRS 2.0 common-rail (up to 1,600 bar) | |
| Emissions standard | Euro 4 (2006–2008); Euro 5 (2009–2013) | |
| Compression ratio | 16.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Garrett GT1749V) | |
| Timing system | Double roller chain (front-mounted) | |
| Oil type | MB 229.51 (SAE 5W-30) | |
| Dry weight | 208 kg |
The V6 configuration delivers strong low-RPM torque ideal for urban and highway driving, but requires adherence to 15,000 km oil change intervals using MB 229.51 specification oil to maintain chain and turbo longevity. Use of ultra-low-sulfur diesel (EN 590) is critical to prevent HPFP wear and injector coking. Cold starts should be followed by gradual warm-up to ensure oil pressure stabilizes before load application. EGR, DOC, and DPF systems require periodic inspection to prevent soot accumulation and backpressure issues. Post-2009 models benefit from revised fuel pump design and improved ECU calibration per SIB 22/2007.
Oil Specs: Requires MB 229.51 (5W-30) specification (Mercedes-Benz SIB 22/2007). Not compatible with ACEA A/B standards.
Emissions: Euro 4 applies to 2006–2008 models; Euro 5 compliance for 2009–2013 units (VCA Type Approval #VCA/EMS/6780).
Power Ratings: Measured under DIN 70020 standards. Output remains consistent across fuel grades meeting EN 590 (Mercedes-Benz TIS Doc. A33510).
Mercedes-Benz Technical Information System (TIS): Docs A32872, A33126, SIB 22/2007
VCA Type Approval Database (VCA/EMS/6780)
SAE International: DIN 70020 Engine Power Test Code
The Mercedes-Benz OM 642.850 was used across Mercedes-Benz's W211/W221/W164 platforms with longitudinal mounting. This engine received platform-specific adaptations-shortened intake manifolds for SUV packaging-and from 2009 the updated emissions calibration for Euro 5 compliance, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the left-side cylinder block near the exhaust manifold (Mercedes-Benz TIS A32917). The 8th VIN digit indicates engine type ('M' for OM 642 series). Pre-2009 models have silver valve covers with ribbed timing covers; post-2009 units retain similar styling but feature updated fuel pump calibration. Critical differentiation from OM 642.950: OM 642.850 has Bosch CRS 2.0 injection with EDC16CP36 ECU, while higher-output variants use different calibration. Service parts require production date verification - fuel filters for pre-2009 builds are not compatible with later units due to housing redesign (Mercedes-Benz SIB 22/2007).
The OM 642.850's primary reliability risk is high-pressure fuel pump wear under sustained load, with elevated incidence in high-mileage fleet use. Internal Mercedes data from 2008 indicated a notable share of pre-2009 units requiring pump replacement before 200,000 km, while UK DVSA records show increased particulate-related failures in urban-operated E-Class models. Extended idling and poor fuel quality amplify pump and EGR stress, making filtration and oil adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2006-2013) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM642850.
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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.
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