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 280SE and 280SEC, the M110.983 was engineered for smooth, high-speed cruising with refined power delivery. Its emissions compliance was achieved through an air injection system and thermal reactor, meeting early European emissions standards (pre-Euro) in domestic markets. The engine's high compression ratio of 9.3:1 required premium-grade fuel for optimal performance.
One documented concern is premature camshaft and follower wear, highlighted in Mercedes-Benz Service Information Bulletin 07 05 82. This issue stemmed from marginal lubrication under sustained high-rpm operation and inadequate oil change intervals. Later production engines received revised camshaft materials and improved oil pump calibration to enhance durability.
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 high-revving nature of the M110.983 provides strong top-end power ideal for highway cruising but demands strict adherence to 15,000 km oil change intervals using high-zinc (ZDDP) formulations to prevent camshaft lobe wear. SAE 20W-50 or 10W-40 oil meeting MB 229.1 specification is critical due to the flat-tappet camshaft design requiring anti-wear additives. Extended idling and low-rpm operation should be minimized to reduce camshaft and follower stress. The Bosch K-Jetronic system requires precise airflow meter calibration and fuel distributor adjustment to maintain drivability. Engines built before 1982 should have camshafts inspected per Mercedes-Benz SIB 07 05 82; later units feature improved metallurgy. Air injection and thermal reactor systems must remain intact for emissions compliance in regulated markets.
Oil Specs: Requires MB 229.1 specification (Mercedes-Benz SIB 07 05 82). High-ZDDP oils recommended for flat-tappet cam protection.
Emissions: Pre-Euro certification applies to all models (VCA Type Approval #VCA/EMS/5678). No Euro 1–6 equivalency.
Power Ratings: Measured under DIN 70020 standards. Output dependent on fuel octane rating (98 RON minimum).
Mercedes-Benz Technical Information System (TIS): Docs A34712, A35104, SIB 07 05 82
VCA Type Approval Database (VCA/EMS/5678)
DIN 70020 Engine Power Measurement Standard
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.
Locate the engine code stamped horizontally on the front of the cylinder block, near the timing chain cover (Mercedes-Benz TIS A34801). The 9th VIN digit indicates engine type ('M' for M110 series). Pre-1981 engines have chrome valve covers with K-Jetronic badges; post-1981 units use black valve covers. Critical differentiation from M110.982: M110.983 features a high-lift camshaft and higher-compression pistons. Service parts require production date verification—camshafts and lifters for engines before 07/1982 are incompatible with later units due to material upgrades (Mercedes-Benz SIB 07 05 82).
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.
Find answers to most commonly asked questions about MERCEDES-BENZ M110983.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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