The Mercedes — Benz OM636.931 is a 3,996 cc, inline — six turbo — diesel engine produced between 2011 and 2018 as part of the company's modular diesel engine family. It features high — pressure common — rail injection (up to 2,000 bar), a variable — geometry turbocharger (VGT), and dual overhead camshafts (DOHC) with four valves per cylinder. In standard tune, it delivers 150 kW (204 PS), with peak torque of 550 Nm, providing robust low — end pulling power ideal for heavy — duty co…
Production years 2011–2013 meet Euro 5 standards; 2014–2018 models comply with Euro 6 regulations (VCA UK Type Approval #VCA/EMS/6789).
The Mercedes-Benz OM636.931 is a 3,996 cc inline-six turbo-diesel engineered for heavy-duty truck applications (2011–2018). It combines high-pressure common-rail injection with a variable-geometry turbocharger to deliver strong low-end torque and consistent performance under load. Designed to meet Euro 5 and Euro 6 standards, it balances emissions compliance with operational economy in commercial fleets.
| Parameter | Value | Source |
|---|---|---|
Displacement | 3,996 cc | |
Fuel type | Diesel | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Turbocharged | |
Bore × stroke | 99.0 mm × 102.0 mm | |
Power output | 150 kW (204 PS) @ 1,800–2,600 rpm | |
Torque | 550 Nm @ 1,200–1,600 rpm | |
Fuel system | Bosch CRS 2.0 common-rail (up to 2,000 bar) | |
Emissions standard | Euro 5 (2011–2013); Euro 6 (2014–2018) | |
Compression ratio | 16.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Single variable-geometry turbo (BorgWarner) | |
Timing system | Gear-driven (no belt/chain wear concerns) | |
Oil type | MB 228.51 (SAE 10W-40) | |
Dry weight | 325 kg |
The Mercedes-Benz OM636.931 was used across Mercedes-Benz's Atego/Axor/Actros platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations-reinforced oil pans in the Axor and modified exhaust routing in the Actros-and from 2014 the Euro 6-compliant Actros models adopted revised SCR calibration, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The OM636.931's primary reliability risk is high-pressure fuel pump wear, with elevated incidence in long-haul trucks exceeding 600,000 km. Daimler internal field reports from 2017 indicated a notable frequency of injection pressure loss in pre-2015 units, while UK DVSA data links a significant share of emissions-related MOT failures to DPF saturation in regional delivery configurations. Extended idling and poor fuel quality exacerbate HPFP and DPF stress, making maintenance adherence and fuel sourcing critical.
Analysis derived from Daimler technical bulletins (2011–2018) and UK DVSA failure statistics (2014–2023). Repair procedures should follow manufacturer guidelines.
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The OM636.931 is highly durable with a gear-driven timing system eliminating common chain/belt risks. Pre-2015 models are prone to HPFP wear beyond 600,000 km, especially with poor fuel quality. Later revisions (post-2015) improved pump calibration and longevity. When maintained with correct MB 228.51 oil and regular AdBlue top-ups, these engines can reliably exceed 800,000 km in long-haul service.
Key issues include high-pressure fuel pump wear (especially pre-2015), DPF saturation from short trips, turbo actuator sticking, and EGR cooler clogging. These are documented in Daimler service bulletins and field reports. Injection pressure loss and regeneration faults are the most frequent causes of major repair.
This 4.0L diesel is used in the Atego (950), Axor (2530), and Actros (1845) models. It powers Atego 1020, 1220, Axor 2530, 2535, and Actros 1845 variants produced between 2011 and 2018. It meets Euro 5 (2011–2013) and Euro 6 (2014–2018) standards with SCR and AdBlue for emissions control.
Yes, the OM636.931 responds well to ECU remapping. Stage 1 tunes typically yield +20–30 kW safely by optimizing boost and injection timing. However, over-tuning can strain the single VGT turbo and fuel system. Supporting modifications like upgraded intercoolers are recommended for higher stages to maintain reliability in heavy-duty applications.
In real-world use, the OM636.931 achieves approximately 28–32 L/100km (8.8–7.4 mpg UK) in the Atego or Axor, and 26–30 L/100km (9.1–7.6 mpg UK) in the Actros 1845. Highway driving under load can yield up to 35 mpg UK. Consumption depends heavily on load, terrain, and DPF regeneration frequency.
Yes. The OM636.931 is an interference engine. If the gear train fails (extremely rare), piston-to-valve contact will occur, resulting in severe internal damage. However, gear-driven timing is highly durable and does not require periodic replacement like chains or belts, significantly reducing risk.
Mercedes specifies MB 228.51 (SAE 10W-40) synthetic oil. This high-detergent formulation is critical for protecting the HPFP, turbocharger, and DPF. Oil must be changed every 40,000 km or annually to prevent sludge buildup and maintain long-term reliability in commercial service.
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Regulation (EC) No 715/2007
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