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 (VCA UK Type Approval #VCA/EMS/5678).
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 | SAE 20W-50 / 10W-40 (MB 229.1) | |
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.
The M110.983's primary reliability risk is camshaft and follower 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-1982 engines requiring camshaft replacement before 150,000 km, while UK DVSA historic vehicle inspection data links mechanical wear to improper oil selection in preserved examples. Sustained high-rpm operation and extended oil intervals increase cam and lifter stress, making oil quality and maintenance adherence critical.
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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MERCEDES-BENZ Official Site
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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
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