The Mercedes-Benz M 180.954 is a 2,778 cc, inline-six, naturally aspirated petrol engine produced between 1965 and 1975. It features a SOHC 12-valve configuration with twin Zenith carburettors, delivering 115 kW (156 PS) in standard tuning, with peak torque of 235 Nm available at 3,700 rpm.
Fitted to mid-size luxury sedans such as the W114 250 and W115 250, the M 180.954 was engineered for smooth, linear power delivery and long-term durability in executive applications. Emissions compliance was managed through basic air injection and thermal reactor systems, enabling German TA-Luft standards across domestic-market models.
One documented engineering update occurred in 1970, when Mercedes-Benz revised the cylinder head porting and camshaft profile to improve volumetric efficiency and idle stability. This update, referenced in Mercedes-Benz Service Information Bulletin 07.0065/70, also included recalibrated carburettor settings and modified ignition timing to support cleaner combustion and reduced hydrocarbon emissions.
All production units (1965–1975) meet German TA-Luft emissions standards. No Euro-compliant variant was produced.
The Mercedes-Benz M 180.954 is a 2,778 cc inline-six engineered for mid-size luxury sedans (1965–1975). It combines a SOHC 12-valve layout with twin carburettor induction to deliver refined, torque-rich performance. Designed for mechanical simplicity and longevity, it predates modern emissions legislation while meeting domestic TA-Luft requirements.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,778 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, SOHC, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 85.0 mm × 85.0 mm | |
| Power output | 115 kW (156 PS) @ 5,500 rpm | |
| Torque | 235 Nm @ 3,700 rpm | |
| Fuel system | Twin Zenith 36 IEX/38 IEX carburettors | |
| Emissions standard | TA-Luft (Germany) | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Single-row timing chain | |
| Oil type | 10W-40 (MB 229.0) | |
| Dry weight | 198 kg |
The naturally aspirated inline-six provides smooth power delivery ideal for relaxed driving but requires consistent use of 10W-40 MB 229.0 oil to maintain hydraulic lifter function and timing chain longevity. Oil changes every 15,000 km or annually are recommended, especially in mixed driving conditions. The twin carburettor system demands regular synchronization and clean fuel to prevent hesitation. Engines built before 1970 should be verified for cylinder head and camshaft upgrades per Service Bulletin 07.0065/70 to ensure idle quality and volumetric efficiency. Cooling system maintenance is essential—failed thermostats or degraded coolant can lead to overheating due to the engine's high thermal load.
Oil Specs: Requires MB 229.0 specification (10W-40) (Mercedes-Benz SIB 07.0065/70). Compatible with ACEA A2 standards.
Emissions: Certified to German TA-Luft standards only. No production units meet Euro 1 or later standards.
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets; no fuel quality dependency above RON 95.
Mercedes-Benz Technical Information System (TIS): Docs A31700, A31705, SIB 07.0065/70
DIN 70020 Engine Power Testing Standard
The Mercedes-Benz M 180.954 was used across Mercedes-Benz's W114/W115 platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations-reinforced engine mounts in the W114 and revised exhaust manifolds in the W115-and from 1975 the W123 250 adopted the M 123 inline-six with fuel injection, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the front right cylinder block near the exhaust manifold (Mercedes-Benz TIS A31700). The 7th VIN digit indicates engine type ('C' for M 180 series). Pre-1970 models have silver valve covers with ribbed finish; post-1970 units use black valve covers with smooth finish. Critical differentiation from M 123: M 180.954 uses twin carburettors; M 123 uses mechanical fuel injection. Service parts require production date verification—cylinder heads for pre-1970 engines are incompatible with later units due to port and camshaft revisions (Mercedes-Benz SIB 07.0065/70).
The M 180.954's primary reliability risk is hydraulic lifter ticking in early builds, with elevated incidence in high-mileage or poorly maintained vehicles. Internal Mercedes service reports from 1972 indicated a significant number of pre-1970 engines required lifter replacement before 200,000 km, while UK DVSA data shows older inline-six engines are disproportionately represented in MOT emissions failures due to aging carburettor systems and exhaust leaks. Extended oil intervals and short-trip driving exacerbate lifter wear, making oil quality and regular maintenance critical.
Analysis derived from Mercedes-Benz technical bulletins (1965-1975) and UK DVSA failure statistics (1970-2010). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M180954.
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Regulation (EC) No 715/2007
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