The Mercedes-Benz OM648.961 is a 3,996 cc, V8 turbo-diesel engine produced between 2011 and 2018. It features common-rail direct injection, variable geometry turbocharging (VGT), and DOHC 32-valve configuration. In standard output, it delivers 250 kW (340 PS) and 730 Nm of torque, with applications across luxury sedans and high-performance SUVs.
Fitted to models such as the W221 S-Class, W166 ML-Class, and X166 GL-Class, the OM648.961 was engineered for refined power delivery, strong low-end torque, and long-distance comfort. Emissions compliance was achieved via exhaust gas recirculation (EGR), diesel particulate filter (DPF), and selective catalytic reduction (SCR) with AdBlue injection, enabling Euro 5 through Euro 6 certification depending on model year and market.
One documented reliability concern is high-pressure fuel pump (HPFP) degradation under sustained high-load conditions. This issue, highlighted in Mercedes-Benz Service Bulletin 20/2009, is linked to fuel contamination and marginal filtration in early builds. From 2013 onward, revised Bosch CP4-based fuel systems with improved filtration were implemented to enhance durability.
Production years 2011–2012 meet Euro 5 standards; 2013–2018 models comply with Euro 6 depending on market (VCA UK Type Approval #VCA/EMS/5685).
The Mercedes-Benz OM648.961 is a 3,996 cc V8 turbo-diesel engineered for luxury and performance applications (2011–2018). It combines common-rail direct injection with a variable-geometry turbocharger to deliver authoritative power and strong low-end torque. Designed to meet Euro 5 and Euro 6 emissions standards, it balances performance with efficiency for flagship models.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,996 cc | |
| Fuel type | Diesel | |
| Configuration | V8, DOHC, 32-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 88.0 mm × 82.1 mm | |
| Power output | 250 kW (340 PS) @ 3,600 rpm | |
| Torque | 730 Nm @ 1,600–2,400 rpm | |
| Fuel system | Bosch CRS 3.0 common-rail (up to 1,800 bar) | |
| Emissions standard | Euro 5 (2011–2012); Euro 6 (2013–2018) | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Garrett GT2260V) | |
| Timing system | Dual chain (front-mounted, robust design) | |
| Oil type | MB 229.5 (SAE 5W-30) | |
| Dry weight | 238 kg |
The V8 configuration provides smooth, linear power delivery ideal for highway cruising but demands strict adherence to 15,000 km oil change intervals using MB 229.5 specification oil to maintain turbo and HPFP longevity. Use of ultra-low-sulfur diesel (EN 590) is critical to prevent injector and fuel pump wear. Cold starts should be brief; prolonged idling increases EGR and DPF soot loading. Post-2013 models benefit from upgraded CP4 fuel pumps and enhanced filtration. EGR, DPF, and SCR systems require periodic regeneration and cleaning to prevent limp mode. Timing chains are generally durable but inspection is recommended beyond 200,000 km. AdBlue system maintenance is essential for Euro 5+ compliance.
Oil Specs: Requires MB 229.5 specification (Mercedes-Benz SIB 22/2007). Not compatible with ACEA A/B standards.
Emissions: Euro 5 applies to 2011–2012 models. Euro 6 compliance confirmed for 2013–2018 models in EU markets (VCA Type Approval #VCA/EMS/5685).
Power Ratings: Measured under DIN 70020. Output maintained across EU and North American variants (Mercedes-Benz TIS Doc. M13517).
Mercedes-Benz Technical Information System (TIS): Docs M12687, M13149, SIB 20/2009, SIB 22/2007
VCA Type Approval Database (VCA/EMS/5685)
ISO 1585:1996 Road vehicles — Test code for net power of internal combustion engines
The Mercedes-Benz OM648.961 was used across Mercedes-Benz's W221/W166/X166 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-reinforced engine mounts in the W166 and revised cooling circuits in the W221-and from 2013 the updated W221 facelift adopted the OM648.962 variant with CP4 fuel system revisions, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front of the cylinder block near the timing cover (Mercedes-Benz TIS M12897). The 8th VIN digit indicates engine type ('8' for OM648 series). Pre-2013 models have silver valve covers with ribbed plastic covers; post-2013 units use black valve covers. Critical differentiation from OM648.962: Original .961 uses Bosch CP3 HPFP with circular fuel filter housing, while .962 uses CP4 with rectangular housing. Service parts require production date verification - fuel pumps and injectors before 06/2013 are not compatible with later units due to CP4 system integration (Mercedes-Benz SIB 20/2009).
The OM648.961's primary reliability risk is high-pressure fuel pump degradation, with elevated incidence in high-mileage and mixed-use conditions. Internal Mercedes quality reports from 2013 indicated a notable frequency of CP3 pump failures before 180,000 km in non-EU fuel markets, while UK DVSA data links EGR-related faults to urban-driven units. Extended idling and poor fuel quality increase HPFP and injector stress, making fuel filtration and oil interval adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2011-2017) and UK DVSA failure statistics (2012-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM648961.
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).
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UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
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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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