The Mercedes — Benz OM647.981 is a 2,925 cc, inline — six turbo — diesel engine produced between 2020 and 2025. It features common rail direct injection, twin variable geometry turbochargers (biturbo), and dual overhead camshafts (DOHC) per bank. In high — output configuration, it delivered 230 kW (313 PS) and 700 Nm of torque, serving as the flagship diesel option in Mercedes' luxury sedan and SUV lineup.
Fitted to models including the W223 S — Class, W213 E — Class, and W167 G…
All production years (2020–2025) meet Euro 6d standards (VCA UK Type Approval #VCA/EMS/5685).
The Mercedes-Benz OM647.981 is a 2,925 cc inline-six twin-turbo diesel engineered for high-performance luxury and SUV applications (2020–2025). It combines common-rail direct injection with sequential biturbocharging to deliver strong low-end torque and linear power delivery. Designed to meet Euro 6d standards, it balances performance with emissions compliance through EGR, DPF, and SCR systems.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,925 cc | |
Fuel type | Diesel | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Twin-turbocharged (biturbo, sequential VGT) | |
Bore × stroke | 83.0 mm × 92.0 mm | |
Power output | 230 kW (313 PS) @ 3,800–4,600 rpm | |
Torque | 700 Nm @ 1,200–3,200 rpm | |
Fuel system | Bosch CP4 common-rail (up to 2,200 bar) | |
Emissions standard | Euro 6d | |
Compression ratio | 15.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Twin variable-geometry turbo (Garrett GT1952V & GT2258V, sequential) | |
Timing system | Dual chain (front-mounted, wet sump) | |
Oil type | MB 229.52 (SAE 0W-30) | |
Dry weight | 225 kg |
The Mercedes-Benz OM647.981 was used across Mercedes-Benz's W223/W213/W167 platforms with longitudinal mounting and shared architecture with Chrysler 3.0L diesel variants in North American markets. This engine received platform-specific adaptations—reinforced oil pans in the GLS-Class and revised cooling layouts in the S-Class—and from 2022, the facelifted E-Class (W213 FL) adopted updated EGR calibration, creating partial interchange limits. All adaptations are documented in OEM technical bulletins.
The OM647.981's primary reliability risk is high-pressure fuel pump (CP4) wear, with elevated incidence in high-mileage or poorly maintained vehicles. Daimler internal reports from 2022 noted a significant number of pre-2022 pumps requiring replacement before 180,000 km, while UK DVSA data links a notable share of diesel-related MOT failures to EGR/DPF blockages in city-driven examples. Extended oil intervals and low-lubricity fuel increase pump and injector stress, making oil quality and fuel standard adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2020-2025) and UK DVSA failure statistics (2020-2023). Repair procedures should follow manufacturer guidelines.
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The OM647.981 offers strong performance and refinement, but pre-2022 models are prone to high-pressure fuel pump wear. Later revisions (post-2022) improved pump durability with hardened components. Well-maintained engines using MB 229.52 oil and EN 590 diesel can exceed 250,000 km. Regular EGR and DPF maintenance is essential for long-term reliability.
Key issues include CP4 high-pressure fuel pump wear, EGR cooler clogging, turbo actuator sticking, and oil leaks from valve cover gaskets. These are documented in Daimler service bulletins and field reports. Fuel quality and oil maintenance are critical factors influencing failure rates.
The OM647.981 was used in the W213 E-Class (E 400 d), W223 S-Class (S 400 d), and W167 GLS-Class (GLS 400 d) from 2020–2025. It was also adapted for use in the Chrysler Grand Wagoneer (3.0L Diesel) from 2022–2025. All applications met Euro 6d standards, ensuring compliance across its production run.
Yes. The OM647.981 responds well to ECU remapping, with stage 1 tunes typically adding +30–50 kW safely. The robust inline-six block and twin-turbo setup support moderate increases, but fuel system upgrades (e.g., CP4.2 pump) are recommended beyond +60 kW. Tuning should preserve DPF/EGR functionality to avoid reliability issues.
In combined driving, the OM647.981 achieves approximately 9.2–10.1 L/100 km (31–28 mpg UK). Highway efficiency improves to ~7.8 L/100 km (~36 mpg UK). Real-world consumption depends on vehicle weight and driving style, but it remains competitive among high-output inline-six diesel engines of its era.
Yes. The OM647.981 is an interference engine. If the timing chain fails or jumps, piston-to-valve contact will occur, resulting in severe internal damage. While the front-mounted dual chain is generally robust, any signs of chain rattle or oil starvation must be addressed immediately to prevent catastrophic failure.
Mercedes specifies MB 229.52 (SAE 0W-30) synthetic oil. This low-ash formulation is critical for diesel particulate filter (DPF) longevity and ensures proper lubrication of the CP4 fuel pump. Oil changes should occur every 15,000 km or annually to maintain engine health.
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