The Mercedes — Benz M104.990 is a 3,498 cc, inline — six naturally aspirated petrol engine produced between 1993 and 1998. It featured a cast — iron block, aluminium head, dual overhead camshafts (DOHC), and sequential multi — point fuel injection (Bosch LH — Jetronic 2.4). Delivering 160 kW (218 PS) and 315 Nm of torque, it was engineered for smooth, refined power delivery in executive sedans and coupes.
Fitted to key models including the W124 350E, W210 E350, and C208 CLK350…
Production years 1993–1996 meet Euro 2 standards; 1997–1998 models comply with Euro 3 (VCA UK Type Approval #VCA/EMS/5682).
The Mercedes-Benz M104.990 is a 3,498 cc inline-six naturally aspirated engine engineered for executive sedans and coupes (1993–1998). It combines DOHC 24-valve architecture with Bosch LH-Jetronic 2.4 electronic fuel injection to deliver smooth power delivery and long-term reliability. Designed to meet evolving emissions regulations, it balances refinement with mechanical durability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 3,498 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 96.5 mm × 80.2 mm | |
Power output | 160 kW (218 PS) @ 5,700 rpm | |
Torque | 315 Nm @ 4,000 rpm | |
Fuel system | Bosch LH-Jetronic 2.4 (electronic sequential multi-point fuel injection) | |
Emissions standard | Euro 2 (1993–1996); Euro 3 (1997–1998) | |
Compression ratio | 10.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Double-row timing chain (non-interference design) | |
Oil type | SAE 10W-40 (MB 229.1) | |
Dry weight | 192 kg |
The Mercedes-Benz M104.990 was used across Mercedes-Benz's W124, W210, and C208 platforms with longitudinal mounting. This engine received platform-specific adaptations—longer intake manifolds in the W210 and revised exhaust manifolds in the C208—and from 1993 the updated oil pump and camshaft lubrication system improved durability, creating service part differentiation. All adaptations are documented in OEM technical bulletins.
The M104.990's primary reliability risk is camshaft and lifter wear on pre-1995 builds, with elevated incidence in high-mileage vehicles. Internal Mercedes quality reports from 1995 noted a significant number of engines requiring camshaft replacement before 180,000 km, while UK DVSA MOT records show increased engine noise and oil consumption in affected units. Extended oil intervals and poor lubricant quality accelerate wear, making oil specification and service adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1993-1998) and UK DVSA failure statistics (1995-2005). Repair procedures should follow manufacturer guidelines.
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The M104.990 is fundamentally robust and capable of high mileage when properly maintained. Pre-1995 models are prone to camshaft wear if oil changes are delayed or incorrect oil is used. Post-1993 revisions significantly improved lubrication reliability. With regular servicing using MB 229.1 10W-40 oil and attention to fuel system components, these engines can exceed 300,000 km.
The most documented issues are camshaft/lifter wear (especially pre-1995), LH-Jetronic fuel distributor faults, intake vacuum leaks, and thermostat housing leaks. These are confirmed in Mercedes service bulletins and technical workshops. Proper maintenance greatly reduces the likelihood of major failures.
The M104.990 was used in the W124 350E (1993–1997), W210 E350 (1995–1998), and C208 CLK350 (1997–1998). It was the larger-displacement inline-six for E-Class and CLK models before being succeeded by the M112 V6 family.
While not commonly tuned, modest gains are possible. Upgraded exhaust systems, performance air filters, and recalibrated fuel distributors can yield +10-15 kW. Camshaft swaps and induction modifications are feasible but require careful tuning. The engine's strong bottom end supports mild modifications, but the DOHC 24-valve head limits high-RPM potential.
In a W210 E350, real-world consumption averages 12.5–14.5 L/100km (19–23 mpg UK) in mixed driving. Highway efficiency improves to ~9.5 L/100km (~30 mpg UK). The LH-Jetronic system offers good drivability but is less efficient than modern injection. Driving style and vehicle condition significantly affect observed economy.
No. The M104.990 uses a non-interference valvetrain design. If the timing chain fails, the pistons will not contact the valves, preventing catastrophic internal damage. This design enhances reliability and reduces repair costs in the event of timing component failure.
Mercedes specifies SAE 10W-40 oil meeting MB 229.1 standard. This viscosity ensures proper lubrication of the camshaft journals and lifters. Oil should be changed every 15,000 km or annually to prevent wear, especially in pre-1995 engines. Using correct oil is critical for long-term reliability.
Comprehensive technical documentation and regulatory references
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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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