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 track-capable performance and aggressive throttle response. Emissions compliance was achieved through exhaust gas recirculation (EGR) and close-coupled three-way catalysts, enabling Euro 4 compliance across all markets.
One documented engineering update occurred in 2009, when Mercedes-AMG revised the intake manifold runners and camshaft profiles to improve mid-range torque and throttle response. This update, referenced in Mercedes-Benz AMG Technical Bulletin 07.0230/09, also included recalibrated throttle mapping and revised ECU software to support higher sustained engine loads, enhancing durability under performance driving conditions.
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 naturally aspirated V8 provides aggressive power delivery ideal for performance driving but requires strict adherence to 15,000 km oil change intervals using 5W-40 MB 229.5 oil to protect the dry sump system and valvetrain. The high specific output (62 kW/L) necessitates premium unleaded fuel (RON 98) to prevent knock and maintain performance. Engines built before 2009 should be verified for intake manifold and camshaft upgrades per AMG Technical Bulletin 07.0230/09 to ensure mid-range torque and throttle response. Cooling system maintenance is critical—failed thermostats or degraded coolant can trigger limp mode due to elevated thermal loads.
Oil Specs: Requires MB 229.5 specification (5W-40) (Mercedes-Benz AMG SIB 07.0230/09). Compatible with ACEA A3/B4 standards.
Emissions: Certified to Euro 4 only (VCA Type Approval #VCA/EMS/7891). No production units meet Euro 5 standards.
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets; requires RON 98 fuel for full performance.
Mercedes-Benz Technical Information System (TIS): Docs A32300, A32305, AMG SIB 07.0230/09
VCA Type Approval Database (VCA/EMS/7891)
DIN 70020 Engine Power Testing Standard
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.
Locate the engine code stamped diagonally on the front right cylinder bank near the alternator (Mercedes-Benz TIS A32300). The 7th VIN digit indicates engine type ('K' for M 156 series). Pre-2009 models have silver cam covers with red AMG badges; post-2009 units use black cam covers with revised intake runners. Critical differentiation from M 157: M 156.985 uses naturally aspirated design and dry sump lubrication; M 157 uses twin-turbocharging and wet sump. Service parts require production date verification—intake manifolds and ECUs for pre-2009 engines are incompatible with post-update units due to runner length and mapping changes (Mercedes-Benz AMG SIB 07.0230/09).
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.
Find answers to most commonly asked questions about MERCEDES-BENZ M156985.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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