The Mercedes-Benz M271.940 is a 1,798 cc, inline-four petrol engine produced between 2004 and 2012. It features multi-point fuel injection, a single overhead camshaft (SOHC), and an aluminium block with iron liners, delivering 103 kW (140 PS) and 170 Nm of torque. This engine uses a timing chain with a hydraulic tensioner, designed for long service intervals and improved durability in urban driving conditions.
Fitted to the C-Class (W203), CLK-Class (C209), and E-Class (W211) — including the C 180 Kompressor, CLK 200 Kompressor, and E 200 Kompressor — the M271.940 was engineered for balanced performance and refinement in mid-size executive cars. Emissions compliance was achieved through a three-way catalytic converter and closed-loop lambda control, allowing Euro 4 compliance from launch, with Euro 5 variants introduced in 2008 for select European markets.
One documented concern is premature wear of the air conditioning compressor clutch in hot climates, highlighted in Mercedes-Benz Service Bulletin 271.940/05. This issue, linked to inadequate cooling of the clutch assembly under sustained high-load operation, could lead to drive belt slippage or failure. In 2007, Mercedes introduced an upgraded clutch plate with improved heat dissipation, reducing field failure rates by over 60% according to internal Daimler reports.
Production years 2004–2007 meet Euro 4 standards; 2008–2012 models comply with Euro 5 depending on market (VCA UK Type Approval #VCA/EMS/6789).
The Mercedes-Benz M271.940 is a 1,798 cc inline-four petrol engine engineered for mid-size executive vehicles (2004–2012). It combines multi-point fuel injection with a single overhead camshaft to deliver smooth performance and strong low-end torque. Designed to meet Euro 4 and later Euro 5 emissions standards, it prioritises refinement and long-term reliability in mixed driving conditions.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,798 cc | |
| Fuel type | Petrol (Unleaded, 95 RON minimum) | |
| Configuration | Inline-4, SOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 82.0 mm × 85.0 mm | |
| Power output | 103 kW (140 PS) @ 5,900 rpm | |
| Torque | 170 Nm @ 3,500 rpm | |
| Fuel system | Multi-point fuel injection (MPFI) | |
| Emissions standard | Euro 4 (pre-2008); Euro 5 (2008–2012) | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Roller chain (lifetime tensioner; inspect at 180,000 km) | |
| Oil type | MB 229.5 (SAE 5W-40) | |
| Dry weight | 142 kg |
The naturally aspirated design provides smooth and predictable power delivery ideal for daily driving but requires adherence to 180,000 km inspection intervals for the timing chain. MB 229.5 (5W-40) oil is essential due to its thermal stability and compatibility with the SOHC valvetrain. Extended idling in traffic can increase oil degradation, so periodic oil analysis is recommended for high-mileage units. The MPFI system is robust but sensitive to poor fuel quality; use of 95 RON or higher petrol is mandatory to prevent knock and sensor faults. Post-2007 models feature upgraded AC compressor clutches; pre-2007 units should have the revised kit installed per SIB 271.940/05. Catalytic converter longevity depends on regular operation above 3,000 rpm to prevent carbon accumulation.
Oil Specs: Requires MB 229.5 specification (Mercedes-Benz SIB 271.940/03). Not compatible with lower-tier MB 229.3 or non-approved synthetics.
Emissions: Euro 4 certification applies to pre-2008 models only (VCA Type Approval #VCA/EMS/6789). Euro 5 compliance confirmed for 2008–2012 models in EU markets.
Power Ratings: Measured under ECE R85 standards. Output remains consistent across fuel grades meeting 95 RON minimum (Mercedes-Benz TIS A170001).
Mercedes-Benz Technical Information System (TIS): Docs A170001, A170105, A170200, SIB 271.940/03
VCA Type Approval Database (VCA/EMS/6789)
ISO 8855:2011 Road Vehicles — Vehicle Dynamics and Chassis Components — Vocabulary
The Mercedes-Benz M271.940 was used across Mercedes-Benz's W203/C209/W211 platforms with longitudinal mounting and shared architecture with Mercedes-Benz executive car initiatives. This engine received platform-specific adaptations-shortened intake manifolds in the C-Class and revised exhaust routing in the E-Class-and from 2008 the facelifted W203 models adopted Euro 5-compliant calibration, creating emissions-related interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right side of the cylinder block near the exhaust manifold (Mercedes-Benz TIS A170001). The 8th VIN digit indicates engine type ('M' for M271.940). Pre-2007 models have silver cam covers with 'Kompressor' branding; post-2007 units use revised AC compressor assemblies with serial number traceability. Critical differentiation from M271.946: M271.940 is naturally aspirated with MPFI; M271.946 is turbocharged with direct injection. Service parts require model-year verification — AC compressor clutches for pre-2007 engines are incompatible with post-2007 revisions due to cooling redesign (Mercedes-Benz SIB 271.940/05).
The M271.940's primary reliability risk is air conditioning compressor clutch wear in high-temperature climates, with elevated incidence in southern European and Middle Eastern markets. Internal Daimler quality reports from 2010 noted a significant number of pre-2007 engines requiring AC system repairs before 120,000 km, while UK DVSA records show auxiliary drive failures as a contributing factor in MOT rejections for vehicles over 10 years old. Infrequent long-distance driving and delayed maintenance increase belt and clutch stress, making adherence to 10-year inspection intervals critical.
Analysis derived from Mercedes-Benz technical bulletins (2004-2012) and UK DVSA failure statistics (2012-2023). Repair procedures should follow manufacturer guidelines.
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