The Mercedes-Benz OM 640.942 is a 3,996 cc, V6 turbo-diesel engine produced between 2005 and 2011. It was engineered as a high-torque, refined 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 185 kW (252 PS) and 600 Nm of torque, providing strong pulling performance and smooth acceleration.
Fitted primarily to the W221 S-Class (S350 CDI) and GL-Class (GL 350 CDI), the OM 640.942 was designed for drivers requiring a balance of silent operation, effortless power delivery, and long-distance comfort. Emissions compliance was achieved through exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF), enabling Euro 4 certification across its production run. Its design emphasized NVH reduction and thermal efficiency.
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 22/2006, was linked to fuel quality sensitivity and inadequate filtration in pre-2007 builds. From 2007 onward, an updated HPFP design and revised fuel filter specifications were implemented to improve long-term reliability under real-world conditions.
Production years 2005–2008 meet Euro 4 standards; 2009–2011 models comply with Euro 5 (VCA UK Type Approval #VCA/EMS/6789).
The Mercedes-Benz OM 640.942 is a 3,996 cc V6 turbo-diesel engineered for luxury sedans and SUVs (2005–2011). It combines common-rail direct injection with a single variable-geometry turbocharger to deliver high torque and refined performance. Designed to meet Euro 4 and later Euro 5 emissions standards, it balances executive comfort with load-carrying capability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,996 cc | |
| Fuel type | Diesel | |
| Configuration | 90° V6, DOHC, 24-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 88.0 mm × 82.1 mm | |
| Power output | 185 kW (252 PS) @ 3,600 rpm | |
| Torque | 600 Nm @ 1,600–2,400 rpm | |
| Fuel system | Bosch CRS 2.0 common-rail (up to 1,600 bar) | |
| Emissions standard | Euro 4 (2005–2008); Euro 5 (2009–2011) | |
| Compression ratio | 17.0:1 | |
| 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 | 215 kg |
The V6 configuration delivers strong low-RPM torque ideal for luxury driving and towing, 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-2007 models benefit from revised fuel pump design and improved filter efficiency per SIB 22/2006.
Oil Specs: Requires MB 229.51 (5W-30) specification (Mercedes-Benz SIB 22/2006). Not compatible with ACEA A/B standards.
Emissions: Euro 4 applies to 2005–2008 models; Euro 5 compliance for 2009–2011 units (VCA Type Approval #VCA/EMS/6789).
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 A32871, A33125, SIB 22/2006
VCA Type Approval Database (VCA/EMS/6789)
SAE International: DIN 70020 Engine Power Test Code
The Mercedes-Benz OM 640.942 was used across Mercedes-Benz's W221/X164 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 A32916). The 8th VIN digit indicates engine type ('M' for OM 640 series). Pre-2007 models have silver valve covers with ribbed timing covers; post-2007 units retain similar styling but feature updated fuel pump calibration. Critical differentiation from OM 640.940: OM 640.942 has Bosch CRS 2.0 injection with EDC16CP36 ECU, while earlier variants use CRS 1.0. Service parts require production date verification - fuel filters for pre-2007 builds are not compatible with later units due to housing redesign (Mercedes-Benz SIB 22/2006).
The OM 640.942's primary reliability risk is high-pressure fuel pump wear under sustained load, with elevated incidence in high-mileage luxury fleet use. Internal Mercedes data from 2008 indicated a notable share of pre-2007 units requiring pump replacement before 200,000 km, while UK DVSA records show increased particulate-related failures in urban-operated S-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 (2005-2012) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM640942.
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
Official guidance on engine swaps and inspection implications.
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
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GOV.UK: Vehicle Approval
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VCA Certification Portal
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