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 commercial applications.
Fitted to models including the Atego (950), Axor (2530), and Actros (1845) variants, the OM636.931 was engineered for durability and fuel efficiency in long-haul and regional freight operations. Emissions compliance is achieved through cooled exhaust gas recirculation (EGR), a diesel particulate filter (DPF), and selective catalytic reduction (SCR) with AdBlue injection, enabling Euro 5 and Euro 6 compliance across its production run.
One documented reliability concern involves high-pressure fuel pump (HPFP) wear, which can result in reduced injection pressure and misfires. This issue, referenced in Daimler Service Information Bulletin 205010/2014, is primarily observed in high-mileage units exceeding 600,000 km. From 2015, revised HPFP calibration and improved lubricity requirements were implemented to extend service life.
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 OM636.931 delivers strong low-end torque ideal for loaded operation but requires strict adherence to 40,000 km oil change intervals using MB 228.51 oil to maintain fuel pump and turbocharger longevity. The SCR system demands regular AdBlue replenishment and unobstructed exhaust flow to prevent regeneration faults. Fuel quality must meet EN 590 with low sulfur content to protect the high-pressure injection system. Gear-driven timing eliminates chain/belt service concerns, enhancing long-term reliability. Post-2014 Euro 6 models require full DPF regeneration cycles; incomplete regens due to short routes can lead to soot saturation and limp mode. HPFP wear beyond 600,000 km should be monitored via injection pressure diagnostics per Daimler SIB 205010/2014.
Oil Specs: Requires MB 228.51 specification (10W-40) (Daimler SIB 205010/2014). Compatible with ACEA E6/E7 standards.
Emissions: Euro 5 applies to 2011–2013 models; Euro 6 certification applies to 2014–2018 units (VCA Type Approval #VCA/EMS/6789).
Power Ratings: Measured under ECE R85 standards. Output maintained across EU markets with EN 590 diesel (Daimler TIS Doc. A41022).
Daimler Technical Information System (TIS): Docs A41022, SIB 205010/2014
VCA Type Approval Database (VCA/EMS/6789)
European Commission Regulation (EU) 582/2011
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.
Locate the engine identification number stamped vertically on the right-side engine block near the flywheel housing (Daimler TIS A41022). The 8th VIN digit indicates engine type ('7' for OM636 series). Pre-2014 models have silver EGR valve housings; post-2014 units use black housings with updated sensors. Critical differentiation from OM651: OM636.931 has a single VGT turbo and gear-driven timing, while OM651 uses a twin-turbo setup and chain-driven camshafts. Service parts require production date verification—HPFP units before 04/2015 are not interchangeable with later versions due to internal recalibration (Daimler SIB 205010/2014).
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.
Find answers to most commonly asked questions about MERCEDES-BENZ OM636931.
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Regulation (EC) No 715/2007
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