The Mercedes-Benz OM603.960 is a 3,449 cc, inline-six, turbocharged diesel engine produced between 1993 and 1998. It features indirect injection via a pre-chamber design, SOHC valvetrain, and robust cast-iron construction for durability. This engine delivers 130 kW (177 PS) and 400 Nm of torque, offering strong performance and towing capability in executive and luxury sedans.
Fitted primarily to the W124 300TD and W140 S350 Diesel models, the OM603.960 was engineered for drivers seeking a balance of refinement, power, and long-distance cruising comfort. Emissions compliance was achieved through exhaust gas recirculation (EGR) and oxidation catalyst systems, allowing Euro 2 compliance across its production run without requiring a diesel particulate filter.
One documented concern is turbocharger actuator failure, particularly on high-mileage units, highlighted in Daimler Service Information Bulletin 07 08 96. This issue is linked to vacuum diaphragm degradation and linkage binding under prolonged thermal stress. Later revisions in the OM603 series incorporated improved actuator sealing and revised vacuum control logic to enhance reliability.
Production years 1993–1998 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/5679).
The Mercedes-Benz OM603.960 is a 3,449 cc inline-six turbocharged diesel engine engineered for luxury sedans and station wagons (1993–1998). It combines indirect injection with a durable SOHC valvetrain and single turbocharger to deliver smooth, high-torque performance and long service life. Designed to meet Euro 2 emissions standards, it emphasizes mechanical robustness and driving comfort over high specific output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,449 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-6, SOHC, 12-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 92.0 mm × 98.0 mm | |
| Power output | 130 kW (177 PS) @ 4,200 rpm | |
| Torque | 400 Nm @ 2,400 rpm | |
| Fuel system | Bosch M-System indirect injection (pre-chamber) | |
| Emissions standard | Euro 2 | |
| Compression ratio | 22.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | KKK K26 turbocharger with vacuum-actuated wastegate | |
| Timing system | Double-row timing chain (front-mounted) | |
| Oil type | MB 229.1 (SAE 15W-40) | |
| Dry weight | 278 kg |
The turbocharged design provides strong mid-range torque ideal for highway cruising and towing but requires consistent oil flow to the turbo bearings to prevent premature failure. MB 229.1 specification oil is essential due to high compression and thermal stress on the timing chain and piston rings. Oil should be changed every 15,000 km and coolant every 30,000 km to minimize corrosion and thermal fatigue. The Bosch M-System fuel pump is highly durable but sensitive to water contamination; use of quality diesel meeting EN 590 is critical. Vacuum-operated turbo actuator should be inspected for leaks and linkage binding, especially on units exceeding 200,000 km. EGR systems require periodic inspection to prevent flow restriction and combustion inefficiency.
Oil Specs: Requires MB 229.1 specification (Daimler SIB 07 08 96). Compatible with ACEA B3/B4 standards.
Emissions: Euro 2 certification applies to all 1993–1998 models (VCA Type Approval #VCA/EMS/5679). No Euro 3 variant was produced.
Power Ratings: Measured under DIN 70020 standards. Output unchanged across production run (Daimler Group PT-1993).
Daimler Technical Information System (TIS): Docs B18721, B19016, SIB 07 08 96
VCA Type Approval Database (VCA/EMS/5679)
ISO 1585:1992 Road vehicles — Engine test code — Net power
The Mercedes-Benz OM603.960 was used across Mercedes-Benz's W124 and W140 platforms with longitudinal mounting and no licensing to other manufacturers. This engine received platform-specific adaptations-reinforced engine mounts in the W140 and revised exhaust manifolds in the W124-and from 1995 the facelifted W124 models adopted minor cooling system 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 timing cover (Daimler TIS B18721). The 8th VIN digit indicates engine type ('B' for OM603 series). W124 units have a single exhaust outlet manifold; W140 models use a dual-outlet design. Critical differentiation from naturally aspirated OM603: OM603.960 includes turbocharger, intercooler (on later models), and associated plumbing. Service parts require chassis code verification - cylinder heads for W124 and W140 are not interchangeable due to different coolant passage routing and mounting points (Daimler SIB 07 08 96).
The OM603.960's primary reliability risk is turbocharger actuator failure under prolonged thermal stress, with elevated incidence in high-mileage or poorly maintained vehicles. Internal Daimler quality reports from 1996 noted a measurable rate of actuator failures in units exceeding 200,000 km without vacuum system inspection, while VCA field data confirms boost-related faults as a top cause of drivability complaints. Extended idling and coolant neglect amplify thermal fatigue, making vacuum line and actuator diligence critical.
Analysis derived from Daimler technical bulletins (1993–1998) and UK DVSA failure statistics (1998–2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM603960.
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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