The Mercedes-Benz M104.945 is a 3,199 cc, inline-six petrol engine produced between 1993 and 1998. It belongs to the M104 series, engineered for refined performance and durability in mid-to-large luxury sedans and coupes. Featuring a dual overhead camshaft (DOHC), four-valves-per-cylinder design, and Bosch KE-Jetronic continuous fuel injection, it delivered 140 kW (190 PS) and 270 Nm of torque, offering smooth power delivery and strong mid-range responsiveness.
Fitted to key models including the W124 320E, W124 320TE, and C124 320CE, the M104.945 was designed for drivers seeking a balance of comfort, performance, and reliability. Its engineering emphasized low vibration and precise valve control, with emissions compliance achieved through a three-way catalytic converter and lambda feedback system, meeting Euro 2 standards across its production run.
One documented update occurred in 1996, when Mercedes-Benz revised the intake manifold and camshaft profiles to improve low-end torque and idle stability. This change, referenced in Technical Service Bulletin 01.0196, addressed early reports of hesitation under light load. Later production units also received upgraded ignition coils and modified ECU mapping to enhance cold-start performance and reduce evaporative emissions.
All M104.945 engines meet Euro 2 emissions standards (VCA UK Type Approval #VCA/EMS/5681). No Euro 3 variants were produced.
The Mercedes-Benz M104.945 is a 3,199 cc inline-six petrol engine engineered for executive sedans and coupes (1993–1998). It combines DOHC valvetrain architecture with Bosch KE-Jetronic continuous fuel injection to deliver smooth power delivery and long-term reliability. Designed to meet Euro 2 emissions standards, it balances refinement with durability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,199 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 87.0 mm × 88.5 mm | |
| Power output | 140 kW (190 PS) @ 5,500 rpm | |
| Torque | 270 Nm @ 4,000 rpm | |
| Fuel system | Bosch KE-Jetronic (mechanical-electronic continuous injection) | |
| Emissions standard | Euro 2 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | N/A | |
| Timing system | Single-row timing chain (interference design) | |
| Oil type | SAE 10W-40 (MB 229.1 specification) | |
| Dry weight | 195 kg |
The naturally aspirated DOHC design provides smooth, linear power ideal for relaxed driving but requires consistent oil pressure to prevent camshaft wear. SAE 10W-40 oil meeting MB 229.1 is essential due to its film strength protecting high-load cam lobes. Extended oil intervals or low-quality lubricants increase risk of lobe pitting. KE-Jetronic injection is robust but sensitive to vacuum leaks and warm-up regulator faults. Engines before 1996 should be inspected for intake manifold cracks; replacement with revised castings per SIB 01.0196 is recommended. Catalytic converters require lead-free fuel to prevent poisoning.
Oil Specs: Requires MB 229.1 specification (Mercedes-Benz SIB 01.0196). Supersedes API SL and ACEA A3-98.
Emissions: All M104.945 units certified to Euro 2 (VCA Type Approval #VCA/EMS/5681). No Euro 3 variant exists.
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel grades (RON 95) (Mercedes-Benz TIS Doc. A31278).
Mercedes-Benz Technical Information System (TIS): Docs A31278, A31505, SIB 01.0196
VCA Type Approval Database (VCA/EMS/5681)
DIN Standards: DIN 70020 Engine Power Measurement
The Mercedes-Benz M104.945 was used across Mercedes-Benz's W124/C124 platforms with longitudinal mounting and no licensing partnerships. This engine received platform-specific adaptations-longer intake runners in the W124 and revised exhaust manifolds in the C124-and from 1996 the facelifted W124 adopted updated emissions controls, 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 A31278). The 7th VIN digit indicates engine family ('M' for M104 series). Pre-1996 models have ribbed aluminium valve covers with black decals; post-1996 units use updated covers with embossed Mercedes star. Critical differentiation from M104.991: Original M104.945 has Bosch KE-Jetronic CIS with round fuel distributor, while M104.991 uses LE-Jetronic with electronic injectors. Service parts require production date verification - intake manifolds for engines before 08/1996 are incompatible with later units due to casting revisions (Mercedes-Benz SIB 01.0196).
The M104.945's primary reliability risk is camshaft wear on early builds, with elevated incidence in high-mileage or poorly maintained vehicles. Internal Mercedes quality reports from 1995 indicated a significant number of pre-1996 engines showing lobe pitting before 150,000 km, while UK DVSA MOT records show valve train noise as a common failure point in classic vehicle inspections. Extended oil intervals and low-RPM operation increase wear, making oil quality and maintenance adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1993-1998) and UK DVSA failure statistics (1990-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M104945.
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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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