The Mercedes — Benz M110.983 is a 2,778 cc, inline — six, naturally aspirated petrol engine produced between 1978 and 1985. It features a single overhead camshaft (SOHC), 12 — valve configuration, and Bosch K — Jetronic mechanical fuel injection. Designed as a high — revving performance variant of the M110 series, it delivered 132 kW (180 PS) at 6,000 rpm and 245 Nm of torque, primarily for the S — Class and SEC coupes.
Fitted to the W116 S — Class and C123 SEC models, including the…
Production years 1978–1985 meet pre-Euro emissions standards; specific certification varies by market .
The Mercedes-Benz M110.983 is a 2,778 cc inline-six naturally aspirated engine engineered for luxury sedans and coupes (1978–1985). It combines SOHC valvetrain architecture with Bosch K-Jetronic continuous fuel injection to deliver high-revving performance and smooth power delivery. Designed to meet pre-Euro emissions standards, it balances refinement with mechanical durability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,778 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, SOHC, 12-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 87.0 mm × 78.0 mm | |
Power output | 132 kW (180 PS) @ 6,000 rpm | |
Torque | 245 Nm @ 3,750 rpm | |
Fuel system | Bosch K-Jetronic mechanical fuel injection | |
Emissions standard | Pre-Euro (air injection + thermal reactor) | |
Compression ratio | 9.3:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Single-row timing chain (SOHC actuation) | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 185 kg |
The Mercedes-Benz M110.983 was used across Mercedes-Benz's W116/C123 platforms with longitudinal mounting and no licensed external usage. This engine received platform-specific adaptations-reinforced engine mounts in the W116 and revised exhaust manifolds in the C123-and from 1981 the facelifted W126 models adopted the M103 engine family, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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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 Mercedes-Benz technical bulletins (1978-1985) and UK DVSA historic vehicle inspection data (1980-2023). Repair procedures should follow manufacturer guidelines.
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The M110.983 offers smooth performance and mechanical refinement, but early models (1978–1981) are prone to camshaft wear if maintenance is neglected. Later revisions (post-1982) improved camshaft durability with better materials. When properly maintained with correct oil (MB 229.1, high-ZDDP) and regular service, these engines can reliably exceed 200,000 km.
Key issues include camshaft and lifter wear (especially pre-1982), K-Jetronic fuel system imbalances, intake manifold coolant leaks, and ignition timing drift. These are documented in Mercedes-Benz service bulletins and verified through technical workshops. Proper maintenance significantly reduces failure rates.
The M110.983 was used in the W116 S-Class (280SE), C123 SEC (280SEC), and early W126 S-Class (280SE/SEL). It was phased out in 1985 with the introduction of the M103 engine family. All applications were luxury sedans and coupes requiring premium fuel and high-revving performance.
Limited tuning potential exists. Modifications include high-performance camshafts, upgraded exhaust manifolds, and K-Jetronic recalibration. Some enthusiasts add Weber carburetors or retrofit electronic injection, but this compromises OEM integrity. Output gains are modest (10–20 kW) due to SOHC and 2-valve limitations.
Moderate for its era. In a W116 280SE, typical consumption is ~14.0 L/100km (city) and ~9.5 L/100km (highway), or about 20 mpg UK combined. Driving style significantly impacts efficiency—smooth operation yields better results. Expect 18–22 mpg (UK) on mixed roads for a well-tuned M110.983.
No. The M110 series uses a non-interference valvetrain design. If the timing chain fails, piston-to-valve contact is unlikely, minimizing catastrophic damage. However, timing chain wear should still be monitored to maintain valve timing accuracy and prevent secondary mechanical issues.
Mercedes-Benz specifies SAE 20W-50 or 10W-40 oil meeting MB 229.1 specification. High-ZDDP (zinc dialkyldithiophosphate) content is essential to protect the flat-tappet camshaft. Oil changes every 10,000–15,000 km are recommended to ensure long-term durability.
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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.
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