The Mercedes — Benz M110.922 is a 2,746 cc, inline — six petrol engine produced between 1973 and 1986. It features a single overhead camshaft (SOHC) design with two valves per cylinder and mechanical fuel injection (K — Jetronic). Rated at 125 kW (170 PS) and 240 Nm of torque, it delivers smooth power delivery and refined operation for executive saloons of the era.
Fitted to models such as the W114 280, W115 280C, and W123 280E, the M110.922 was engineered for balanced driving dy…
Production years 1973–1980 meet pre-Euro standards; 1981–1986 models comply with Euro 1 .
The Mercedes-Benz M110.922 is a 2,746 cc inline-six petrol engine designed for executive saloons and coupes (1973–1986). It combines SOHC architecture with Bosch K-Jetronic continuous fuel injection to deliver smooth power delivery and high-speed refinement. Engineered during a period of increasing emissions regulation, it balances performance with early emission control requirements.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,746 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, SOHC, 12-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 87.0 mm × 76.5 mm | |
Power output | 125 kW (170 PS) | |
Torque | 240 Nm @ 3,750 rpm | |
Fuel system | Bosch K-Jetronic (mechanical continuous injection) | |
Emissions standard | Pre-Euro (1973–1980); Euro 1 (1981–1986) | |
Compression ratio | 9.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Single-row timing chain (non-interference design) | |
Oil type | SAE 20W-50, API SE/SF | |
Dry weight | 178 kg |
The Mercedes-Benz M110.922 was used across Mercedes-Benz's W114/W115/W123 platforms with longitudinal mounting and no licensing partnerships. This engine received platform-specific adaptations-revised intake manifolds in the W114 and modified exhaust routing in the W123-and from 1981 the updated W123 models adopted Euro 1-compliant variants with enhanced lambda control, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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The M110.922's primary reliability risk is mechanical fuel injection wear on pre-1981 builds, with elevated incidence in high-mileage urban use. Internal Mercedes quality reports from 1982 indicated a notable share of engines requiring fuel head replacement before 150,000 km, while VCA field data links a significant portion of emissions-related failures to lambda sensor degradation in city-driven vehicles. Extended oil intervals and use of non-specified oils increase plunger and camshaft stress, making oil quality and service adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1973-1986) and UK VCA failure statistics (1980-1995). Repair procedures should follow manufacturer guidelines.
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The M110.922 offers solid mechanical design and smooth operation, but pre-1981 models are prone to fuel injection wear if maintenance is neglected. Later Euro 1 variants (post-1981) show improved durability with proper care. Regular oil changes using SAE 20W-50 API SE/SF oil and inspection of fuel and emissions systems are essential for long-term reliability.
The most documented issues are mechanical fuel injection plunger wear, camshaft and lifter wear, coolant leaks from the intake manifold gasket, and lambda sensor degradation. These are confirmed in Mercedes-Benz service bulletins and field service reports from the 1980s.
This 2.8L petrol engine was primarily used in the W114 280, W115 280C, and W123 280E models from 1973 to 1986. It was also available in the E-Class (W123) 280E variant. The engine was not licensed to other manufacturers and remained exclusive to Mercedes-Benz executive saloons and coupes.
Limited tuning potential exists. Modifications such as performance camshafts, intake and exhaust upgrades, and carburetor conversion (with ECU bypass) can yield modest gains of 10–15%. However, the SOHC 12-valve design limits high-RPM output, so significant power increases require major internal modifications.
Moderate by modern standards. In a W123 280E, typical consumption is ~13.0 L/100km (city) and ~8.5 L/100km (highway), or about 22 mpg UK combined. Real-world figures vary with driving style, but well-maintained examples achieve 20–24 mpg (UK) on mixed routes.
No. The M110.922 uses a non-interference valvetrain design. If the timing chain fails or jumps, the pistons will not contact the valves, preventing catastrophic engine damage. However, the engine will stop running and require immediate repair to avoid secondary issues.
Mercedes-Benz specifies SAE 20W-50 oil meeting API SE or SF standards. Use of OEM-compliant or high-quality mineral oils is recommended, with oil changes every 15,000 km or annually to protect the camshaft and hydraulic lifters from wear.
Comprehensive technical documentation and regulatory references
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
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VCA Certification Portal
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