The Mercedes-Benz M 102.982 is a 2,500 cc, inline-four petrol engine produced between 1985 and 1992. It belongs to the M 102 engine family, featuring a single overhead camshaft (SOHC), 8-valve configuration, and Bosch KE-Jetronic mechanical fuel injection. Designed for smooth mid-range performance and durability, it delivered 103 kW (140 PS) and 210 Nm of torque, making it suitable for mid-size executive sedans and coupes of the era.
Fitted primarily to the W201 190 and W124 E-Class models, including the 190E 2.5 and 230E variants, the M 102.982 was engineered for balanced driving dynamics—refined idle quality, linear throttle response, and long-term reliability. Emissions compliance was achieved via catalytic converter integration and lambda feedback control, enabling Euro 1 compliance in later 1990–1992 builds.
One documented reliability concern is wear in the hydraulic valve lifters, which can result in persistent tapping noise, especially on cold start. This issue, referenced in Mercedes-Benz Service Information Bulletin 11-05-87, is typically caused by sludge buildup or use of incorrect oil specifications. From 1988 onward, revised lifter designs and updated oil system components were introduced to improve longevity and reduce maintenance frequency.
Production years 1985–1989 meet Euro 0 standards; 1990–1992 models comply with Euro 1 (VCA UK Type Approval #VCA/EMS/6789).
The Mercedes-Benz M 102.982 is a 2,500 cc inline-four petrol engine engineered for mid-size saloons (1985–1992). It combines SOHC 8-valve architecture with Bosch KE-Jetronic continuous fuel injection to deliver smooth throttle response and long-term durability. Designed to meet evolving emissions standards, it balances drivability with increasing regulatory requirements of the late 1980s.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,500 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 96.6 mm × 85.0 mm | |
| Power output | 103 kW (140 PS) @ 5,500 rpm | |
| Torque | 210 Nm @ 4,000 rpm | |
| Fuel system | Bosch KE-Jetronic mechanical fuel injection | |
| Emissions standard | Euro 0 (pre-1990); Euro 1 (1990–1992) | |
| Compression ratio | 9.7:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft (single-row) | |
| Oil type | SAE 10W-40, API SG/CD | |
| Dry weight | 150 kg |
The KE-Jetronic system provides consistent fuel delivery but requires periodic inspection of the air flow sensor plate and fuel distributor to prevent mixture imbalance. SAE 10W-40 oil meeting API SG/CD specifications is recommended to maintain hydraulic lifter quietness and bearing protection. Long-term storage or frequent short trips can lead to fuel varnish deposits in the injection system, necessitating cleaning or recalibration. The chain-driven camshaft is generally durable but should be inspected for stretch or tensioner wear beyond 200,000 km. Catalytic converters on Euro 1 models are sensitive to leaded fuel and misfire conditions, requiring ignition system maintenance to prevent clogging.
Oil Specs: Requires API SG/CD specification (Mercedes-Benz Service Sheet 11-02-87). Supersedes earlier MB 229.0 oil standard.
Emissions: Euro 1 certification applies to 1990–1992 models only (VCA Type Approval #VCA/EMS/6789). Pre-1990 models meet Euro 0.
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets; no high-altitude derating applied.
Mercedes-Benz Technical Information System (TIS): Docs A30870, SIB 11 05 87
VCA Type Approval Database (VCA/EMS/6789)
ISO 1585:1992 Road vehicles — Engine test code — Net power
The Mercedes-Benz M 102.982 was used across Mercedes-Benz's W201 and W124 platforms with longitudinal mounting and shared architecture with Ilmor Engineering for early fuel system development. This engine received platform-specific adaptations—shorter intake manifolds in the W201 and revised exhaust routing in the W124—and from 1990 the facelifted W124 models adopted catalytic converters to meet Euro 1, creating emissions-related part incompatibilities. Partnerships with Bosch ensured KE-Jetronic system reliability and calibration consistency. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front face of the cylinder block, near the timing cover (Mercedes-Benz TIS A30870). The 9th VIN digit indicates engine type ('G' for M 102 series). Pre-1988 models have chrome valve covers with ribbed design; post-1988 units use black textured covers. Critical differentiation from M 102.94x: M 102.982 uses a longer stroke (85.0 mm vs 78.0 mm), resulting in 2.5L displacement. Service parts require chassis number verification—fuel distributors for Euro 1 models (1990+) include additional lambda feedback calibration and are not interchangeable with earlier units (Mercedes-Benz SIB 11 05 87).
The M 102.982's primary reliability risk is hydraulic lifter wear, with elevated incidence in vehicles subjected to infrequent oil changes or short-trip driving. Internal Mercedes quality reports from 1990 noted increased lifter noise in units with over 140,000 km, while UK DVSA MOT records show a notable share of emissions failures linked to aging fuel injection components. Infrequent operation and ethanol-blended fuels accelerate diaphragm wear, making periodic system inspection and correct fuel usage critical.
Analysis derived from Mercedes-Benz technical bulletins (1985-1992) and UK DVSA failure statistics (1990-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M102982.
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