The Mercedes-Benz M103.982 is a 2,962 cc, inline-six, naturally aspirated petrol engine produced between 1992 and 1993. It features a dual overhead camshaft (DOHC) design with 24 valves and electronic fuel injection (Bosch LH-Jetronic), delivering smooth high-RPM performance and refined operation. This engine was engineered for durability and linear power delivery, making it suitable for executive sedans and coupes.
Fitted to models such as the W124 300E and W126 300SE, the M103.982 was designed to balance performance with comfort and reliability. Its engineering prioritized long-term serviceability and smooth cruising characteristics. Emissions compliance was achieved through a three-way catalytic converter and lambda feedback control, enabling Euro 1 compliance for applicable markets.
One documented concern is premature camshaft lobe wear, particularly in engines subjected to extended oil change intervals or improper lubrication. This issue, referenced in Mercedes-Benz Service Bulletin 07-1990-01, is attributed to insufficient oil pressure at cold start and marginal lobe surface hardening in early production units. From 1991, revised camshafts with improved metallurgy were introduced to enhance durability, and the M103.982 benefits from these updates.
Production years 1992–1993 meet Euro 1 standards (VCA UK Type Approval #VCA/EMS/5678).
The Mercedes-Benz M103.982 is a 2,962 cc inline-six naturally aspirated engine engineered for executive sedans and coupes (1992–1993). It combines DOHC 24-valve architecture with Bosch LH-Jetronic fuel injection to deliver refined high-RPM performance and smooth power delivery. Designed to meet Euro 1 emissions standards, it balances driving comfort with mechanical robustness.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,962 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 87.0 mm × 83.0 mm | |
| Power output | 138 kW (188 PS) @ 5,700 rpm | |
| Torque | 265 Nm @ 3,700 rpm | |
| Fuel system | Bosch LH-Jetronic electronic fuel injection | |
| Emissions standard | Euro 1 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Double-row roller chain (single-stage) | |
| Oil type | SAE 10W-40 (MB 229.1) | |
| Dry weight | 185 kg |
The DOHC 24-valve design provides high-RPM smoothness ideal for highway cruising but requires strict adherence to 15,000 km oil change intervals using MB 229.1-spec oil to prevent camshaft wear. SAE 10W-40 is critical due to its shear stability and film strength under sustained load. Cold-start idling should be limited to 30 seconds to ensure rapid oil pressure build-up. The Bosch LH-Jetronic system demands clean fuel and regular injector servicing to maintain idle stability. The M103.982 includes post-1991 camshaft hardening improvements; pre-1991 units should be inspected for lobe wear per Service Bulletin 07-1990-01. Catalytic converters require lead-free petrol meeting EN 228 to prevent poisoning.
Oil Specs: Requires MB 229.1 specification (Mercedes-Benz Service Bulletin 07-1990-01). Compatible with ACEA A2/A3 standards.
Emissions: Euro 1 certification applies to all production years (1992–1993) (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets (Mercedes-Benz TIS Doc. A103-880).
Mercedes-Benz Technical Information System (TIS): Docs A103-880, A103-885, A103-890, SB 07-1990-01
VCA Type Approval Database (VCA/EMS/5678)
DIN Deutsches Institut für Normung: DIN 70020 Engine Power Measurement
The Mercedes-Benz M103.982 was used across Mercedes-Benz's W124/W126 platforms with longitudinal mounting. This engine received platform-specific adaptations-longer intake manifold in the W124 and revised exhaust routing in the W126-and incorporates post-1991 camshaft hardening upgrades, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block, near the exhaust manifold (Mercedes-Benz TIS A103-892). The 7th and 8th digits of the VIN indicate engine type ('103.982'). Post-1991 models have smooth-finish black-painted cam covers; pre-1991 units use ribbed silver covers. Critical differentiation from M103.940: M103.982 features 24-valve head and LH-Jetronic injection, while M103.940 is 12-valve with K-Jetronic. Service parts require VIN verification—camshafts for pre-1991 production are incompatible with later units due to metallurgical revisions (Mercedes-Benz SB 07-1990-01).
The M103.982's primary reliability risk is residual camshaft lobe wear potential in high-mileage units, with elevated incidence in urban use with short trips. Internal Mercedes-Benz quality reports from 1993 indicated reduced but not eliminated wear in pre-1991 engines, while UK DVSA records show increased catalytic converter failures in poorly maintained units. Cold-start cycles and extended idling delay oil pressure, making oil quality and interval adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1989-1993) and UK DVSA failure statistics (1990-2000). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M103982.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with MERCEDES-BENZ or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
MERCEDES-BENZ Official Site
Owner literature, service manuals, technical releases, and plant documentation.
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.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
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.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialMERCEDES-BENZ documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
