The Mercedes — Benz M 156.984 is a 6,208 cc, V8 petrol engine produced between 2006 and 2011. It features a naturally aspirated DOHC 32 — valve design with direct fuel injection (CGI) and dry sump lubrication, delivering 386 kW (525 PS) and 630 Nm of torque. This high — revving engine was engineered for maximum responsiveness and track — capable performance in AMG applications.
Fitted to the CLK 63 AMG (C209), E 63 AMG (W211), and SL 63 AMG (R230), the M 156.984 targeted performan…
All production years (2006–2011) meet Euro 4 emissions standards .
The Mercedes-Benz M 156.984 is a 6,208 cc V8 petrol engine designed for high-performance AMG models (2006–2011). It combines naturally aspirated architecture with direct fuel injection and dry sump lubrication to deliver track-focused performance and driver engagement. Designed to meet Euro 4 emissions standards, it balances high-RPM power with everyday drivability in performance-oriented applications.
| 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 | Direct fuel injection (CGI) | |
Emissions standard | Euro 4 | |
Compression ratio | 11.3:1 | |
Cooling system | Water-cooled | |
Turbocharger | N/A | |
Timing system | Double-row roller chain (front-mounted) | |
Oil type | 10W-60 MB-Approval 229.5 | |
Dry weight | 201 kg |
The Mercedes-Benz M 156.984 was used across Mercedes-Benz's C209/W211/R230 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-tuned intake manifolds in the R230 and reinforced engine mounts in the W211-and from 2009 the facelifted W211 received updated ECU mapping, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Engine Finders UK Ltd, which operates EngineCode.uk, can pass your enquiry to engine suppliers in the UK. The service is for vehicles in the United Kingdom, with UK delivery or fitting. This is a commercially connected service, and sending an enquiry does not confirm diagnosis or compatibility.
Diagnostic reminder: If a technician has recommended replacing the engine, you can send an enquiry to engine suppliers in the UK. Confirm the diagnosis first: an engine-code record does not diagnose a fault.
Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The M 156.984 offers high-revving, naturally aspirated performance but early models (2006–2008) had reliability concerns, particularly high-pressure fuel pump drive wear. Later revisions (post-2008) improved durability with reinforced components and revised inspection intervals. Well-maintained examples with regular servicing and correct oil (10W-60 MB-Approval 229.5) can be robust. Cold-start procedures and adherence to oil change intervals are critical for longevity.
The primary issues are high-pressure fuel pump drive lobe wear (especially pre-2008), ignition coil degradation, oil leaks from valve and front covers, and intake manifold actuator failure. These are well-documented in Mercedes-Benz service bulletins. Secondary concerns include fuel injector coking and catalytic converter blockage due to high fuel consumption and infrequent highway driving.
This 6.3L V8 was used in the CLK 63 AMG (C209) from 2006–2010, the E 63 AMG (W211) from 2006–2009, and the SL 63 AMG (R230) from 2008–2011. It was not licensed to other manufacturers. All applications were Euro 4 compliant, with no Euro 5 version produced.
Limited tuning potential exists due to the naturally aspirated design. ECU remaps can yield modest gains (~15–25 kW) by optimizing fuel and ignition maps. Aftermarket upgrades like high-flow exhausts and intake systems offer minor improvements. However, the engine's strength lies in its high-RPM character, so significant power increases require forced induction, which is complex and costly due to the dry sump and high-compression design.
Fuel consumption is very high due to displacement and performance tuning. In an E 63 AMG (W211), typical use is ~19.5 L/100km (city) and ~11.2 L/100km (highway), or about 14 mpg UK combined. Real-world figures often range between 11–15 mpg (UK) depending on driving style. Highway cruising is more efficient than urban use due to the engine's high-RPM torque characteristics.
Yes. The M 156.984 is an interference engine. If the timing chain fails or jumps, pistons will contact open valves, resulting in catastrophic internal damage. Chain maintenance and proper lubrication are essential—any unusual front-end noise should be investigated immediately to prevent engine seizure.
Mercedes-Benz specifies 10W-60 oil meeting MB-Approval 229.5. Use only high-quality synthetic oils designed for high-load petrol engines. Change intervals should not exceed 15,000 km or annually. Proper oil selection ensures adequate fuel pump drive lubrication and reduces wear in the timing chain system.
Comprehensive technical documentation and regulatory references
EngineCode.uk is operated by Engine Finders UK Ltd. It provides engine-reference information and an optional commercial enquiry service. It is not an official manufacturer website. Check the record's sources and confirm vehicle-specific details before relying on it for parts, repairs or replacement.
Our editorial standard prioritises relevant manufacturer documentation and official regulatory sources. The sources and verification status for a record should be checked alongside the data.
A statement is not verified merely because a source is listed. Where supporting evidence is missing or conflicting, the record should identify that limitation. Please report unsupported or inconsistent information.
Transparency in gaps
A missing or unverified value does not mean the manufacturer has withheld it. We distinguish information not yet verified, information not available to us, and information explicitly not disclosed by the source.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
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)
UK type-approval authority for automotive products.
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
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Records are subject to review and correction. Source links, dates and verification notes should be read with the technical information. Our Editorial and Sourcing Policy explains our standards and review process.
Found an error or missing source? Report a problem with this page. Include the field or statement concerned and a supporting source if available. You can also email corrections@enginecode.uk.
Copyright and permissions
Images and other material may be protected by copyright. Attribution does not by itself grant permission to reuse material. If you believe material on this site infringes your rights, contact copyrights@enginecode.uk with the page URL and details of your claim. We will review the material and take appropriate action.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
Our Privacy Policy explains how Engine Finders UK Ltd uses information from visits, vehicle lookups, enquiries and messages. Our Cookie Policy explains cookies and similar technologies and how to change your choices.
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
Ownership and commercial services
EngineCode.uk is owned and operated by Engine Finders UK Ltd. Alongside our reference content, we offer an optional replacement-engine enquiry service through Engine Finders and may identify relevant services provided by businesses connected with us. These commercial connections are disclosed. Using an enquiry service is not required to read our reference content.
Engine Finders UK Ltd operates this website. Our optional enquiry service has a commercial purpose. Our Ownership and Commercial Disclosure explains the relationship between the reference website and that service. Participating suppliers pay a fee or subscription to participate on the network and receive quote requests.
Use this record as a starting point for identification. Specifications and vehicle applications may contain errors or omissions. Confirm the exact engine variant and compatibility using vehicle-specific documentation and a qualified supplier or technician.
All external links open in new tabs. Please verify current availability of resources.