The Mercedes — Benz M111.973 is a 2,295 cc, inline — four, naturally aspirated petrol engine produced between 1999 and 2004. It features a single overhead camshaft (SOHC), 16 — valve configuration, and Bosch Motronic ME 2.1 electronic fuel injection. Designed for balanced performance in compact and mid — size luxury models, it delivered 110 kW (150 PS) at 5,500 rpm and 220 Nm of torque, primarily for the C — Class and CLK — Class.
Fitted to the W202 C — Class and C208 CLK — Class mod…
Production years 1999–2004 meet Euro 3 standards; specific certification varies by market .
The Mercedes-Benz M111.973 is a 2,295 cc inline-four naturally aspirated engine engineered for compact and mid-size luxury models (1999–2004). It combines SOHC valvetrain architecture with Bosch Motronic ME 2.1 sequential fuel injection to deliver smooth, linear power delivery. Designed to meet Euro 3 emissions standards, it balances refinement with mechanical reliability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,295 cc | |
Fuel type | Petrol | |
Configuration | Inline-4, SOHC, 16-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 89.0 mm × 92.0 mm | |
Power output | 110 kW (150 PS) @ 5,500 rpm | |
Torque | 220 Nm @ 4,000 rpm | |
Fuel system | Bosch Motronic ME 2.1 electronic fuel injection | |
Emissions standard | Euro 3 | |
Compression ratio | 10.3:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Timing chain (SOHC actuation) | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 148 kg |
The Mercedes-Benz M111.973 was used across Mercedes-Benz's W202/C208 platforms with transverse mounting and no licensed external usage. This engine received platform-specific adaptations-reinforced mounts in the C208 and compact intake routing in the W202-and from 2004 the facelifted W203 models adopted the M271 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 (1999-2004) and UK DVSA historic vehicle inspection data (1995-2023). Repair procedures should follow manufacturer guidelines.
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The M111.973 offers smooth performance and compact efficiency, but early models (1999–2000) are prone to camshaft wear if maintenance is neglected. Later revisions (post-2001) 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 180,000 km.
Key issues include camshaft and lifter wear (especially pre-2001), idle instability from IACV or vacuum leaks, coolant leaks from water pump, and ignition timing drift. These are documented in Mercedes-Benz service bulletins and verified through technical workshops. Proper maintenance significantly reduces failure rates.
The M111.973 was used in the W202 C-Class (C230), C208 CLK-Class (CLK230), and early W203 C-Class (C230 Kompressor). It was phased out in 2004 with the introduction of the M271 engine family. All applications were front-wheel-drive platforms requiring premium fuel and balanced performance.
Limited tuning potential exists. Modifications include high-performance camshafts, upgraded intake manifolds, and ECU remapping. Some enthusiasts add performance exhausts or throttle bodies, but this compromises OEM integrity. Output gains are modest (10–15 kW) due to SOHC and 4-valve limitations.
Efficient for its era. In a W202 C230, typical consumption is ~9.8 L/100km (city) and ~6.5 L/100km (highway), or about 34 mpg UK combined. Driving style significantly impacts efficiency—smooth operation yields better results. Expect 30–36 mpg (UK) on mixed roads for a well-tuned M111.973.
No. The M111 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 10W-40 or 5W-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.
Comprehensive technical documentation and regulatory references
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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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VCA Certification Portal
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