The Mercedes-Benz M 157.984 is a 5,461 cc, twin-turbocharged V8 petrol engine produced between 2011 and 2017. It served as the high-performance AMG powerplant for select luxury and performance models, featuring a 90° V8 layout with dual overhead camshafts (DOHC) and 32 valves. In standard tune, it delivered 430 kW (585 PS), with peak torque of 800 Nm, providing aggressive throttle response and track-capable performance.
Fitted to the W221 S-Class, W218 CLS, and C218 CLS AMG variants, the M 157.984 was engineered for dynamic driving and high-speed stability. Its design emphasized forced-induction power delivery and acoustic character, with spray-guided direct injection, twin-scroll turbochargers, and dry-sump lubrication ensuring consistent oil pressure under high lateral loads. Emissions compliance was achieved through advanced lambda control and dual catalytic converters, meeting Euro 5 standards across its production run.
One documented concern is premature wear of the high-pressure fuel pump, which can lead to fuel delivery faults and engine stalling. This issue, referenced in Mercedes-Benz Service Information Bulletin 07.0026/06, is attributed to mechanical stress and fuel quality sensitivity in high-pressure GDI systems. Later production revisions introduced reinforced pump internals and updated control algorithms to improve durability.
All production years 2011–2017 meet Euro 5 emissions standards (VCA UK Type Approval #VCA/EMS/5683).
The Mercedes-Benz M 157.984 is a 5,461 cc twin-turbo V8 petrol engine engineered for high-performance applications (2011–2017). It combines forced induction with direct injection to deliver explosive power and track-focused dynamics. Designed to meet Euro 5 standards, it balances high-output performance with street usability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,461 cc | |
| Fuel type | Petrol | |
| Configuration | 90° V8, DOHC, 32-valve | |
| Aspiration | Twin-turbocharged | |
| Bore × stroke | 82.6 mm × 85.6 mm | |
| Power output | 430 kW (585 PS) @ 5,500 rpm | |
| Torque | 800 Nm @ 2,000–4,500 rpm | |
| Fuel system | Spray-guided direct injection (up to 200 bar) | |
| Emissions standard | Euro 5 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Twin-scroll turbochargers (BorgWarner), chargecooled | |
| Timing system | Double-row roller chain (SOHC-style drive with DOHC cams) | |
| Oil type | SAE 5W-40 MB 229.5 | |
| Dry weight | 228 kg |
The twin-turbo V8 provides explosive, low-end torque ideal for performance driving but demands high-octane fuel (RON 98) to prevent knock and maintain injector cleanliness. SAE 5W-40 MB 229.5 oil is essential due to its high-temperature stability and anti-wear protection for turbo and bearing systems. Oil changes should not exceed 15,000 km or 24 months to prevent sludge and turbo degradation. The spray-guided injection system requires periodic cleaning to maintain combustion efficiency. Pre-2014 engines should be inspected for high-pressure fuel pump integrity per Mercedes SIB 07.0026/06; updated pumps with reinforced internals were introduced mid-cycle to enhance durability. Cooling system integrity is critical—leaks or thermostat faults can lead to overheating due to high thermal load.
Oil Specs: Requires MB 229.5 specification (Mercedes SIB 07.0026/06). Compatible with ACEA A3/B4.
Emissions: Euro 5 certification applies to all models (2011–2017) (VCA Type Approval #VCA/EMS/5683).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting RON 95 minimum (Mercedes TIS Doc. A36016).
Mercedes-Benz Technical Information System (TIS): Docs A35725, A36016, SIB 07.0026/06
VCA Type Approval Database (VCA/EMS/5683)
DIN 70020: Engine Power Measurement Standard
The Mercedes-Benz M 157.984 was used across Mercedes-Benz's W221, W218, and C218 platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations-reinforced engine mounts in the W221 and shortened accessory drives in the C218-and from 2014 the facelifted W221 models adopted revised intake manifolds and updated engine management, 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 TIS A35725). The 8th VIN digit indicates engine type ('M' for M157 series). Pre-2014 engines have silver cam covers with "63 AMG" badging; post-2014 units feature revised intake plenum and updated ECU. Critical differentiation from M156: M157 uses twin-turbocharging with direct injection, while M156 (naturally aspirated) has individual throttle bodies and port injection. Service parts require model-year verification—fuel pumps and turbo components for pre-2014 engines are incompatible with later revisions due to internal reinforcement and control updates (Mercedes SIB 07.0026/06).
The M 157.984's primary reliability risk is high-pressure fuel pump wear on early builds, with elevated incidence in high-mileage performance use. Internal Mercedes quality reports from 2015 noted a significant number of pre-2014 engines requiring fuel pump replacement before 120,000 km, while UK DVSA records indicate cooling system failures as a leading cause of overheating-related breakdowns. Extended service intervals and poor coolant maintenance increase wear and thermal stress, making fluid and oil discipline critical.
Analysis derived from Mercedes-Benz technical bulletins (2011-2017) and UK DVSA failure statistics (2013-2018). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M157984.
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)
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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
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VCA Certification Portal
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