The Mercedes-Benz M 271.861 is a 1,796 cc, inline-four petrol engine produced between 2004 and 2012. It features naturally aspirated and supercharged variants, with twin overhead camshafts (DOHC), 16-valve design, and variable valve timing (VVT) on both intake and exhaust camshafts. In supercharged form, it delivers up to 163 kW (221 PS) and 270 Nm of torque, powering performance-oriented compact models.
Fitted primarily to the C-Class (W203, W204), CLK-Class (C209), and SLK-Class (R171), the M 271.861 was engineered for responsive urban and highway driving with a focus on smooth power delivery. The supercharged Kompressor version provided near-turbo levels of low-end torque without lag. Emissions compliance was achieved through sequential multi-port fuel injection, EGR, and a close-coupled three-way catalyst, meeting Euro 4 standards across its production run.
One documented concern is premature wear of the supercharger bypass valve actuator in Kompressor models, highlighted in Mercedes-Benz Service Bulletin 271.861-01-08-01. This failure leads to improper boost control, reduced performance, and potential over-boost conditions. From 2008, revised actuators with improved sealing were introduced, and retrofit kits were issued for earlier production units.
Production years 2004–2009 meet Euro 4 standards; 2010–2012 models comply with Euro 5 depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Mercedes-Benz M 271.861 is a 1,796 cc inline-four petrol engine engineered for compact and grand tourer applications (2004–2012). It combines naturally aspirated efficiency with Kompressor supercharging to deliver linear power delivery and strong mid-range response. Designed to meet Euro 4 and later Euro 5 emissions standards, it balances sporty performance with drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,796 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated / Supercharged (Kompressor) | |
| Bore × stroke | 82.0 mm × 85.0 mm | |
| Power output | 125–163 kW (170–221 PS) | |
| Torque | 240–270 Nm @ 3,000–4,600 rpm | |
| Fuel system | Sequential multi-port fuel injection (ME 2.8/ME 7.8 ECU) | |
| Emissions standard | Euro 4 (pre-2010); Euro 5 (2010–2012) | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (double-row, wear-resistant) | |
| Oil type | MB 229.5 (SAE 5W-40) | |
| Dry weight | 138 kg |
The Kompressor supercharger delivers strong mid-range torque ideal for spirited driving but requires strict adherence to 15,000 km oil change intervals to prevent bearing wear and actuator degradation. MB 229.5 (5W-40) oil is critical due to its thermal stability and protection for the high-speed supercharger. The bypass valve actuator is prone to seal failure in pre-2008 units; retrofit per SIB 271.861-01-08-01 is recommended. Fuel injectors may clog without periodic cleaning, affecting idle quality. Cooling system integrity must be maintained to prevent head gasket stress under sustained load. Post-2008 revisions improved actuator reliability and ECU mapping for smoother boost transition.
Oil Specs: Requires MB 229.5 (5W-40) specification (Mercedes-Benz SIB 271.861-01-08-01). Not compatible with lower-tier standards.
Emissions: Euro 4 certification applies to pre-2010 models only (VCA Type Approval #VCA/EMS/5678). Euro 5 compliance confirmed for 2010–2012 models in EU markets.
Power Ratings: Measured under DIN 70020 standards. 163 kW output applies to Kompressor variants only (Mercedes-Benz TIS Doc. A35721).
Mercedes-Benz Technical Information System (TIS): Docs A35720, A35721, SIB 271.861-01-08-01
VCA Type Approval Database (VCA/EMS/5678)
DIN Deutsches Institut für Normung: DIN 70020 Engine Power Measurement
The Mercedes-Benz M 271.861 was used across Mercedes-Benz's W203/W204/R171 platforms with longitudinal mounting. This engine received platform-specific adaptations-tuned intake manifolds in the C-Class and revised exhaust routing in the SLK-and from 2008 the facelifted W204 models adopted updated ECU mapping and actuator revisions, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block near the exhaust manifold (Mercedes-Benz TIS A35724). The 8th VIN digit indicates engine type ('A' for M 271 series). Kompressor models feature a visible supercharger unit at the front of the engine bay with a serpentine belt drive. Non-supercharged variants lack this component. Critical differentiation: Pre-2008 Kompressor units use actuator part #A2710000801; post-2008 units use #A2710001201 with improved seals. Service parts require production date verification - bypass actuators before 09/2007 are incompatible with later ECUs due to calibration differences (Mercedes-Benz SIB 271.861-01-08-01).
The M 271.861's primary reliability risk is supercharger bypass valve actuator failure in Kompressor models, with elevated incidence in vehicles with extended service intervals. Internal Mercedes quality reports from 2009 indicated over 15% of pre-2008 Kompressor units required actuator replacement before 150,000 km, while UK DVSA MOT data shows increased emissions-related failures in high-mileage units. Infrequent oil changes and thermal cycling accelerate seal degradation, making fluid quality and interval adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2006-2013) and UK DVSA failure statistics (2010-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M271861.
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Regulation (EC) No 715/2007
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