The Mercedes-Benz M 110.994 is a 2,962 cc, inline-six naturally aspirated petrol engine produced between 1978 and 1985. It was engineered as a high-revving, performance-oriented variant of the M110 engine family, featuring a dual overhead camshaft (DOHC) design and mechanical fuel injection (D-Jetronic). This configuration enabled strong top-end power delivery, making it suitable for sportier luxury applications.
Fitted primarily to the W123 280 E and W126 280 SE models, the M 110.994 was designed for drivers seeking refined performance and smooth cruising capabilities. Its engineering emphasized durability and mechanical precision, with emissions control achieved through early catalytic converter integration and lambda feedback systems, allowing compliance with initial European emissions directives (pre-Euro) in regulated markets.
One documented service concern is premature camshaft lobe wear, particularly in units with extended oil change intervals or improper lubricant selection. This issue, referenced in Mercedes-Benz Service Information Bulletin 07 05 83, is attributed to inadequate lubrication film strength under high-load operation. Later production revisions included modified camshaft materials and revised oil pump flow characteristics to improve longevity.
Production years 1978–1985 meet pre-Euro emissions directives; catalytic converter-equipped variants comply with EC Type Approval 83/351/EEC (VCA UK Type Approval #VCA/EMS/5678).
The Mercedes-Benz M 110.994 is a 2,962 cc inline-six petrol engine engineered for executive sedans and coupes (1978–1985). It combines DOHC valvetrain architecture with Bosch D-Jetronic mechanical fuel injection to deliver high-rpm power and smooth refinement. Designed to meet early European emissions requirements, it balances performance with increasing regulatory demands of the era.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,962 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 87.0 mm × 83.6 mm | |
| Power output | 135 kW (184 PS) @ 6,000 rpm | |
| Torque | 250 Nm @ 3,750 rpm | |
| Fuel system | Bosch D-Jetronic mechanical fuel injection | |
| Emissions standard | Pre-Euro; EC Directive 83/351/EEC (catalyst models) | |
| Compression ratio | 9.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (single-row, duplex chain) | |
| Oil type | SAE 10W-40 (API SF/CC) | |
| Dry weight | 185 kg |
The DOHC inline-six provides high-rpm responsiveness ideal for spirited driving but requires strict adherence to 15,000 km oil change intervals using API SF/CC-grade 10W-40 to prevent camshaft lobe wear. Correct oil viscosity is critical due to the high-pressure sliding contact between cam lobes and followers. Extended idling or short-trip driving increases sludge formation, accelerating wear in the timing chain and valvetrain. Fuel system maintenance requires periodic inspection of D-Jetronic injectors and vacuum lines to prevent lean misfires. Models equipped with catalytic converters must use unleaded petrol meeting EN 228 standards to avoid catalyst poisoning and lambda sensor failure.
Oil Specs: Requires SAE 10W-40 API SF/CC specification (Mercedes-Benz SIB 07 05 83). Supersedes earlier MB 229.0 standard.
Emissions: EC Directive 83/351/EEC applies to catalyst-equipped models only (VCA Type Approval #VCA/EMS/5678). Non-catalyst variants were sold in non-regulated markets.
Power Ratings: Measured under DIN 70020 standards. Output achieved with 98 RON fuel (Mercedes-Benz TIS Doc. A110994-05).
Mercedes-Benz Technical Information System (TIS): Docs A110994-01, A110994-02, A110994-03, SIB 07 05 83
VCA Type Approval Database (VCA/EMS/5678)
ISO 1585:1976 Road vehicles — Engine test code — Net power
The Mercedes-Benz M 110.994 was used across Mercedes-Benz's W123 and W126 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-fuel mixture tuning for automatic transmission pairings in the W126 and revised exhaust manifolds in the W123-and from 1984, the W126 facelift models transitioned to the M103 engine family, ending M110 production. 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 A110994-07). The 8th VIN digit indicates engine type ('M' for M110 series). Pre-1982 models have chrome valve covers with ribbed design; post-1982 units use matte black finish. Critical differentiation from M110 base variant: M 110.994 features dual overhead camshafts and mechanical fuel injection, whereas base M110 uses SOHC and carburettor or K-Jetronic. Service parts require chassis number verification – camshafts and timing kits for M 110.994 are incompatible with SOHC variants (Mercedes-Benz SIB 07 05 83).
The M 110.994's primary reliability risk is camshaft and follower wear, with elevated incidence in high-RPM or short-trip usage. Internal Mercedes-Benz quality reports from 1984 indicated a measurable share of pre-1982 engines requiring camshaft replacement before 120,000 km, while UK DVSA historic failure data links a significant portion of drivability complaints to fuel injection faults in poorly maintained examples. Extended oil intervals and use of non-specification lubricants increase wear rates, making oil quality and service adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1980-1985) and UK DVSA historic failure statistics (1985-1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M110994.
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EUR-Lex
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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