The Mercedes — Benz M 110.982 is a 2,966 cc, inline — six naturally aspirated petrol engine produced between 1978 and 1985. It features a dual overhead camshaft (DOHC) design with mechanical fuel injection (D — Jetronic) and was engineered for smooth high — RPM performance. This engine delivers 147 kW (200 PS) at 6,000 rpm and 275 Nm of torque, with a high 9.3:1 compression ratio enabling strong power delivery.
Fitted primarily to the W123 280E and W126 280SE models, the M 110.9…
Production years 1978–1980 meet Euro 1 standards; 1981–1985 models comply with enhanced emissions protocols depending on market .
The Mercedes-Benz M 110.982 is a 2,966 cc inline-six naturally aspirated engine engineered for executive sedans and coupes (1978–1985). It combines DOHC valvetrain architecture with Bosch D-Jetronic mechanical fuel injection to deliver high-RPM responsiveness and smooth power delivery. Designed to meet early Euro emissions standards, it balances performance with durability for long-distance driving.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,966 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 87.0 mm × 83.6 mm | |
Power output | 147 kW (200 PS) @ 6,000 rpm | |
Torque | 275 Nm @ 3,750 rpm | |
Fuel system | Bosch D-Jetronic mechanical fuel injection | |
Emissions standard | Euro 1 (1978–1980); enhanced protocols (1981–1985) | |
Compression ratio | 9.3:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Chain-driven (double-row, duplex), rear-mounted | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 185 kg |
The Mercedes-Benz M 110.982 was used across Mercedes-Benz's W123/W126 platforms with longitudinal mounting. This engine received platform-specific adaptations-shorter intake manifolds in the W123 and revised exhaust manifolds in the W126-and from 1981 the facelifted W126 models adopted enhanced emissions hardware, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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The M 110.982's primary reliability risk is camshaft lobe wear on early builds, with elevated incidence in high-mileage or poorly maintained vehicles. Internal Mercedes-Benz quality reports from 1983 noted a significant number of pre-1981 engines requiring camshaft replacement before 150,000 km, while VCA records indicate a notable share of emissions failures linked to air injection system degradation. Extended oil intervals and use of non-specification oils increase wear risk, making oil quality and adherence to service schedules critical.
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 110.982 is a robust inline-six with strong performance, but early models (1978-1980) are prone to camshaft lobe wear if maintenance is deferred. Later revisions (post-1981) with updated oilways are significantly more durable. Regular oil changes with correct specification oil (10W-40 API SF/CC) and adherence to service intervals are essential for long-term reliability.
The primary issues are camshaft lobe wear (especially in pre-1981 engines), fuel distributor calibration drift, and air injection system failures. Secondary concerns include oil leaks from valve covers and intake manifolds. These are well-documented in Mercedes-Benz service bulletins and technical workshops.
This 3.0L DOHC petrol engine was used in select high-performance variants of the W123 and W126 series. It powered the W123 280E, W126 280SE, and C123 280CE coupes from 1978 to 1985. It was not used in other model lines or by partner manufacturers.
Limited tuning potential exists. Performance gains are typically achieved through carburetor conversion (e.g., triple Weber setup) or fuel injection remapping, though these deviate from OEM design. Exhaust and ignition upgrades can improve breathing and timing precision. However, the engine's high-RPM nature already extracts most of the factory potential.
Moderate for its era. In a W123 280E, typical consumption is ~14.0 L/100km (city) and ~9.5 L/100km (highway), or about 20 mpg UK combined. Real-world figures vary significantly with driving style, but expect 18–22 mpg (UK) on mixed roads for a well-maintained M 110.982.
Yes. The M 110 series is an interference engine. If the timing chain fails or jumps, pistons can contact open valves, resulting in severe internal damage. Regular inspection of the chain tensioner and guides is critical, especially on high-mileage engines.
Mercedes-Benz specifies SAE 10W-40 oil meeting API SF/CC standards. Use of high-detergent, zinc-containing oil is recommended to protect the camshaft lobes. Oil should be changed every 10,000–15,000 km or annually to ensure consistent lubrication and prevent oilway blockages.
Comprehensive technical documentation and regulatory references
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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.
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