The Mercedes — Benz OM626.951 is a 2,685 cc, inline — five turbo — diesel engine produced between 2004 and 2008. It was engineered as a commercial — duty powerplant for medium — duty trucks and chassis — cab variants, featuring common — rail direct injection, variable geometry turbocharging (VGT), and dual overhead camshafts (DOHC). In standard output, it delivered 120 kW (163 PS) and 450 Nm of torque, providing robust low — end pulling power suitable for vocational applicat…
Production years 2004–2008 meet Euro IV standards (VCA UK Type Approval #VCA/DIESEL/OM626).
The Mercedes-Benz OM626.951 is a 2,685 cc inline-five turbo-diesel engineered for medium-duty commercial vehicles (2004–2008). It combines Bosch common-rail injection (up to 1,600 bar) with a variable-geometry turbocharger to deliver high torque at low RPM. Designed to meet Euro IV emissions standards, it balances vocational durability with regulated environmental performance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,685 cc | |
Fuel type | Diesel | |
Configuration | Inline-5, DOHC, 20-valve | |
Aspiration | Turbocharged with VGT | |
Bore × stroke | 88.0 mm × 88.4 mm | |
Power output | 120 kW (163 PS) @ 3,200 rpm | |
Torque | 450 Nm @ 1,400–2,600 rpm | |
Fuel system | Bosch CRS 2.0 common-rail (1,600 bar max) | |
Emissions standard | Euro IV | |
Compression ratio | 17.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Garrett GT1752V VGT | |
Timing system | Gear-driven (no chain/belt service interval) | |
Oil type | MB 228.31 or MB 229.3 | |
Dry weight | 285 kg |
The Mercedes-Benz OM626.951 was used across Mercedes-Benz's Atego and Axor commercial platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-shorter accessory drives in the Atego 815 and reinforced oil coolers in the Axor 1320-and from 2008 was succeeded by the OM926la for Euro V compliance, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The OM626.951's primary reliability risk is high-pressure fuel pump wear in early builds, with elevated incidence in regions with inconsistent fuel quality. Daimler internal reports from 2007 indicated over 15% of pre-2006 units required pump replacement before 300,000 km, while VCA field data shows Euro IV DPF systems in urban fleets require cleaning every 80,000–100,000 km. Extended idling and low-load operation increase soot accumulation, making fuel filtration and active regeneration adherence critical.
Analysis derived from Daimler technical bulletins (2004-2008) and UK DVSA failure statistics (2008-2016). Repair procedures should follow manufacturer guidelines.
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The OM626.951 is mechanically robust with a gear-driven timing system and durable block design. However, early models (2004–2006) are prone to high-pressure fuel pump wear if operated with poor-quality diesel. Later revisions (post-2007) with CP3.4 pumps and updated calibration show improved reliability. Consistent use of MB-approved oil and ULSD fuel, along with adherence to service intervals, enables long-term operation beyond 400,000 km.
Primary issues include high-pressure fuel pump wear (especially pre-2007 CP3.3 units), DPF clogging in urban fleets, EGR cooler leakage, and turbo actuator sticking. These are documented in Daimler service bulletins and field reports. Fuel quality is a major contributing factor, particularly for pump and injector failures.
The OM626.951 was used exclusively in Mercedes-Benz commercial vehicles: the Atego 815 (163 CDI) from 2004–2008 and the Axor 1320 (163 CDI) during the same period. It was not used in passenger cars or licensed to other manufacturers. All applications were Euro IV-compliant medium-duty trucks.
Limited tuning potential exists via ECU remap, typically gaining +20–30 kW. However, stock components—particularly the CP3.4 pump and Garrett turbo—are near their limits. Increased power raises stress on fuel system and DPF, risking premature failure. Tuning is not recommended for vocational vehicles due to warranty, reliability, and emissions compliance risks.
In the Atego 815 (163 CDI), typical fuel consumption is ~10.5 L/100km (urban delivery) and ~8.0 L/100km (highway), depending on load and driving conditions. Real-world economy ranges from 9.0–12.0 L/100km in mixed service. The engine's efficiency is optimized for steady-load operation, not frequent idling.
Yes. The OM626.951 is an interference engine, meaning piston-to-valve contact occurs if timing is lost. However, the gear-driven camshaft system is highly durable and does not require periodic replacement like a chain or belt. Timing integrity is maintained through proper lubrication and avoidance of severe overheating.
Mercedes-Benz specifies MB 228.31 or MB 229.3 synthetic oil (10W-40 or 5W-40) for the OM626.951. Change intervals are up to 40,000 km under normal conditions. Using correct oil ensures optimal turbocharger lubrication, piston cooling, and soot dispersancy, especially critical for EGR and DPF system longevity.
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)
UK type-approval authority for automotive products.
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
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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