The Mercedes-Benz OM611.961 is a 2,151 cc, inline-four, turbocharged diesel engine produced between 1998 and 2002. It features direct injection via a unit injector (PLD) system and a robust SOHC valvetrain with mechanical valve adjustment. Designed for improved efficiency and responsiveness, it delivered 75 kW (102 PS) and 230 Nm of torque, offering enhanced performance over its indirect-injection predecessors.
Fitted to models such as the W210 200CDI, W202 C-Class, and Vito (W638), the OM611.961 was engineered for urban and regional driving with a focus on fuel economy and reduced emissions. Emissions compliance was achieved through direct injection precision and an oxidation catalyst, meeting Euro 3 standards as required by EU Directive 97/68/EC during its production window.
One documented concern is premature high-pressure fuel pump wear, particularly in high-mileage applications with inconsistent fuel quality. This issue, referenced in Mercedes-Benz Service Information Bulletin 07 07 01, is typically associated with water contamination and particulate ingress in non-filtered diesel supplies. Later production runs incorporated revised pump seals and stricter fuel filtration protocols, with field inspections recommended for vehicles operating in remote regions.
Production years 1998–2002 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/7890).
The Mercedes-Benz OM611.961 is a 2,151 cc inline-four diesel engine engineered for compact and light commercial vehicles (1998–2002). It combines direct injection with a turbocharged SOHC valvetrain to deliver responsive performance and improved fuel efficiency. Designed to meet Euro 3 emissions standards, it prioritizes drivability and serviceability over high specific output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,151 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 88.0 mm × 88.3 mm | |
| Power output | 75 kW (102 PS) | |
| Torque | 230 Nm @ 1,800 rpm | |
| Fuel system | Bosch PLD unit injector (direct injection) | |
| Emissions standard | Euro 3 | |
| Compression ratio | 18.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single fixed-geometry turbo (KKK K14) | |
| Timing system | Chain-driven camshaft (SOHC) | |
| Oil type | SAE 10W-40, ACEA B3/B4 | |
| Dry weight | 175 kg |
The turbocharged design provides strong low-RPM torque ideal for city driving and light load carrying but requires proper cooldown after heavy loads to prevent turbo bearing damage. SAE 10W-40 oil meeting ACEA B3/B4 specifications is essential to maintain lubrication integrity under sustained load. Regular valve clearance checks (every 30,000 km) are critical due to mechanical tappets. The PLD unit injector system is sensitive to fuel quality; use of non-compliant diesel can lead to injector coking and misfires. Fuel pump inspections are advised if water contamination is suspected, as per SIB 07 07 01. Cooling system maintenance is paramount to prevent thermal stress in prolonged operation.
Oil Specs: Requires SAE 10W-40, ACEA B3/B4 specification (Mercedes-Benz SIB 07 07 01). Compatible with MB 229.1 where applicable.
Emissions: Euro 3 certification applies to all models (1998–2002) (VCA Type Approval #VCA/EMS/7890).
Power Ratings: Measured under DIN 70020 standards. Output unchanged across production run (Mercedes-Benz Group PT-1998).
Mercedes-Benz Technical Information System (TIS): Docs M166-611, SIB 07 07 01
VCA Type Approval Database (VCA/EMS/7890)
EU Directive 97/68/EC - Emissions for Light-Duty Vehicles
The Mercedes-Benz OM611.961 was used across Mercedes-Benz's W202/W210/W638 platforms with longitudinal mounting and utilised in both passenger and commercial derivatives. This engine received platform-specific adaptations-reinforced oil pans in van applications and modified intake manifolds in W210 sedans-and from 2000 the updated W210 LCI models adopted revised cooling configurations, creating interchange limits. 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 M166-611). The 8th VIN digit indicates engine type ('5' for OM611 series). Pre-2000 units have a cast iron exhaust manifold; post-2000 variants may feature a steel unit. Critical differentiation from OM611.960: OM611.961 includes turbocharging and has a distinct PLD injector calibration. Service parts require chassis number verification—fuel pumps from pre-2000 builds are not interchangeable with later units due to revised seals per SIB 07 07 01.
The OM611.961's primary reliability risk is high-pressure fuel pump failure under contaminated fuel conditions, with elevated incidence in commercial-use vehicles with poor fuel maintenance. Internal Mercedes quality reports from 1999 noted recurring pump failures in Vito vans operating in remote areas, while VCA MOT data links a significant portion of pre-2002 diesel failures to fuel system neglect. Extended idling and infrequent filter changes increase contamination risk, making regular system maintenance critical.
Analysis derived from Mercedes-Benz technical bulletins (1998-2002) and UK DVSA failure statistics (1999-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM611961.
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Regulation (EC) No 715/2007
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