The Mercedes-Benz OM642.820 is a 3,009 cc, V6 turbo-diesel engine produced between 2006 and 2013. It features common rail direct injection, variable geometry turbocharging (VGT), and DOHC valvetrain with 24 valves. In standard output form, it delivers 150 kW (204 PS) and 540 Nm of torque, providing strong mid-range performance ideal for executive and SUV applications.
Fitted to the W211 E-Class (E320 CDI), W221 S-Class (S320 CDI), and W164 ML-Class (ML320 CDI), the OM642.820 was engineered to balance responsive power delivery with improved fuel economy over the older inline-six diesels. Emissions compliance was achieved via cooled exhaust gas recirculation (EGR), diesel particulate filter (DPF), and oxidation catalyst, meeting Euro 4 standards initially, with later models complying with Euro 5.
One documented reliability concern is high-pressure fuel pump (HPFP) internal wear, particularly in early production units. This issue, referenced in Mercedes-Benz Service Bulletin 20/2007, is attributed to insufficient lubricity in early ultra-low-sulfur diesel formulations. From 2009, revised HPFP internals and updated fuel additive specifications were introduced to improve durability.
Production years 2006–2008 meet Euro 4 standards; 2009–2013 models comply with Euro 5 (VCA UK Type Approval #VCA/EMS/6789).
The Mercedes-Benz OM642.820 is a 3,009 cc V6 turbo-diesel engineered for executive and SUV platforms (2006–2013). It combines common-rail direct injection with a single variable-geometry turbocharger to deliver responsive mid-range torque and smooth power delivery. Designed to meet Euro 4 and later Euro 5 standards, it balances refinement with regulated emissions compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,009 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 1,800 bar) | |
| Emissions standard | Euro 4 (2006–2008); Euro 5 (2009–2013) | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Garrett GT1749V) | |
| Timing system | Dual chain (front-mounted, robust design) | |
| Oil type | MB 229.51 (SAE 5W-30) | |
| Dry weight | 198 kg |
The OM642.820 provides strong low-to-mid-range torque ideal for urban and highway driving but requires adherence to 15,000 km oil change intervals using MB 229.51 specification oil to protect the HPFP and turbocharger. Use of EN 590 ultra-low-sulfur diesel is mandatory to prevent injector and pump damage. The Bosch CRS 2.0 system is sensitive to fuel contamination; pre-filter maintenance is advised in regions with variable fuel quality. Early HPFP units (pre-2009) should be inspected per SIB 20/2007; updated pumps with hardened components are recommended for longevity. DPF and EGR systems require periodic regeneration and inspection to maintain emissions compliance and prevent backpressure issues.
Oil Specs: Requires MB 229.51 (5W-30) specification (Mercedes-Benz SIB 20/2007). Not compatible with older 229.31 or ACEA A3/B4 oils.
Emissions: Euro 4 applies to 2006–2008 models; Euro 5 certification for 2009–2013 models (VCA Type Approval #VCA/EMS/6789).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel grades meeting EN 590 (Mercedes-Benz TIS Doc. A36820).
Mercedes-Benz Technical Information System (TIS): Docs A36012, A36215, SIB 20/2007
VCA Type Approval Database (VCA/EMS/6789)
ISO 1585: Road vehicles — Engine test code — Net power
The Mercedes-Benz OM642.820 was used across Mercedes-Benz's W211/W221/W164 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific tuning variations-smooth idle control in the W221 and revised transmission mapping in the W164-and from 2009 incorporated HPFP durability updates per service bulletin, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine ID plate mounted on the left-side cylinder head near the intake manifold (Mercedes-Benz TIS A36025). The 8th VIN digit indicates engine type ('H' for OM642 series). Pre-2009 models have a Bosch HPFP with black housing and serial prefix 0445 010 002; post-2009 units use a revised pump with silver housing and prefix 0445 010 005. Critical differentiation from OM629: OM642.820 has a 90° V6 configuration with front-mounted timing covers, while OM629 is an inline-five. Service parts require VIN and production date verification—HPFP kits for pre-2009 engines are not interchangeable with updated designs (Mercedes-Benz SIB 20/2007).
The OM642.820's primary reliability risk is high-pressure fuel pump degradation, with elevated incidence in high-mileage vehicles subjected to extended oil intervals. Internal Mercedes-Benz quality reports from 2009 indicated a notable share of pre-2009 pumps requiring replacement before 200,000 km, while UK DVSA records show diesel-related failures in W211/W221 models often trace to fuel system contamination. Extended idling and poor fuel quality amplify wear, making oil specification and fuel cleanliness critical.
Analysis derived from Mercedes-Benz technical bulletins (2006-2013) and UK DVSA failure statistics (2010-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM642820.
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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