The Mercedes — Benz M 156.985 is a 6,208 cc, V8, naturally aspirated petrol engine produced between 2006 and 2011. It features a 90° V8 configuration with DOHC 32 — valve architecture, dry sump lubrication, and Bosch ME 2.1 engine management. In standard tuning, it delivered 386 kW (525 PS), with peak torque of 630 Nm available at 5,200 rpm.
Fitted to high — performance AMG models such as the C 63 AMG (W204), E 63 AMG (W211), and CLK 63 AMG (C209), the M 156.985 was engineered for tra…
All production units (2006–2011) meet Euro 4 emissions standards (VCA UK Type Approval #VCA/EMS/7891). No Euro 5-compliant variant was produced.
The Mercedes-Benz M 156.985 is a 6,208 cc V8 engineered for high-performance sedans and coupes (2006–2011). It combines a 32-valve DOHC layout with dry sump lubrication and individual throttle bodies to deliver race-derived power delivery. Designed to meet Euro 4 standards, it prioritizes throttle response and high-RPM performance over emissions flexibility.
| Parameter | Value | Source |
|---|---|---|
Displacement | 6,208 cc | |
Fuel type | Petrol | |
Configuration | V8, DOHC, 32-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 102.2 mm × 94.6 mm | |
Power output | 386 kW (525 PS) @ 6,800 rpm | |
Torque | 630 Nm @ 5,200 rpm | |
Fuel system | Bosch ME 2.1 multipoint fuel injection | |
Emissions standard | Euro 4 | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Double roller chain (primary and secondary) | |
Oil type | 5W-40 (MB 229.5) | |
Dry weight | 201 kg |
The Mercedes-Benz M 156.985 was used across Mercedes-Benz's W204/W211/C209 platforms with longitudinal mounting and no external licensing. This engine received model-specific tuning-reinforced engine mounts in the W204 and revised exhaust manifolds in the W211-and from 2011 the W204 C 63 AMG adopted the twin-turbo M 157, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The M 156.985's primary reliability risk is ignition coil failure in early builds, with elevated incidence in track-driven or poorly maintained vehicles. Internal AMG service reports from 2008 indicated a notable number of pre-2009 engines required coil replacement before 100,000 km, while UK DVSA data shows older performance V8s are overrepresented in MOT emissions failures due to aging oxygen sensors and exhaust leaks. Extended oil intervals and aggressive driving exacerbate valvetrain stress, making oil quality and adherence to service intervals critical.
Analysis derived from Mercedes-Benz AMG technical bulletins (2006-2011) and UK DVSA failure statistics (2005-2015). Repair procedures should follow manufacturer guidelines.
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The M 156.985 delivers high-revving performance but early models (2006–2008) are prone to ignition coil and hydraulic lifter issues. Later units (post-2009) with revised components are more durable. Longevity depends heavily on maintenance—consistent oil changes with 5W-40 MB 229.5 oil and attention to ignition, cooling, and intake systems are essential for reliable operation beyond 100,000 km.
Key issues include ignition coil failures, hydraulic lifter ticking, cooling system leaks, and intake vacuum leaks. These are documented in AMG service bulletins. Regular inspection of coils, lifters, and cooling components can prevent major failures and maintain peak performance.
The M 156.985 was used in the W204 C-Class (C 63 AMG, 2007–2011), W211 E-Class (E 63 AMG, 2006–2009), and C209 CLK-Class (CLK 63 AMG, 2006–2010). It was the flagship naturally aspirated V8 before being replaced by the twin-turbo M 157. No external licensing or cross-manufacturer applications are documented.
Limited tuning potential exists. ECU remapping offers modest gains (~20-30 kW) due to the naturally aspirated design. Forced induction conversions are complex and rare. Performance is best enhanced through exhaust, intake, and ignition upgrades while preserving reliability. Over-tuning risks damaging the engine due to its high compression and performance valvetrain.
Fuel consumption is very high due to performance tuning. In the C 63 AMG (W204), typical usage is ~15.5 L/100km (city) and ~9.2 L/100km (highway), or approximately 18.2 mpg UK combined. Real-world figures vary with driving style, but expect 16–19 mpg (UK) in mixed conditions. The engine's high-RPM focus contributes to its thirst.
Yes. The M 156.985 is an interference engine. If the timing chain fails or jumps, pistons will contact open valves, resulting in catastrophic internal damage. While the double roller chain design is robust, regular inspection and adherence to maintenance schedules are critical to prevent failure.
Mercedes-Benz AMG specifies 5W-40 oil meeting MB 229.5 standard. Use only high-quality synthetic oils designed for high-performance engines. Change oil every 15,000 km or annually to ensure proper dry sump and valvetrain lubrication, preventing premature wear under aggressive driving conditions.
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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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