The BMW M30 B34 (346KA) is a 3,430 cc, inline — six naturally aspirated petrol engine produced from 1988 to 1995. Part of BMW's long — running M30 engine family, it features a single overhead camshaft (SOHC), 12 — valve configuration, and Bosch Motronic 1.3 fuel injection. It delivers 155 kW (211 PS) in standard tune with peak torque of 305 Nm.
Fitted to high — end BMW models including the E32 7 Series and E34 5 Series, the M30 B34 (346KA) was designed as a powerful and refined powerp…
Production years 1988–1995 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/0346).
The BMW M30 B34 (346KA) is a 3,430 cc inline-six naturally aspirated petrol engine engineered for luxury and executive models (1988–1995). It combines Bosch Motronic 1.3 fuel injection with a robust SOHC valvetrain to deliver smooth, linear power delivery. Designed to meet Euro 2 emissions standards, it represents the final evolution of BMW's naturally aspirated inline-six before the advent of the M50 engine.
| Parameter | Value | Source |
|---|---|---|
Displacement | 3,430 cc | |
Fuel type | Petrol (Unleaded, 95 RON min) | |
Configuration | Inline-6, SOHC, 12-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 89.0 mm × 92.0 mm | |
Power output | 155 kW (211 PS) @ 5,800 rpm | |
Torque | 305 Nm @ 4,000 rpm | |
Fuel system | Bosch Motronic 1.3 fuel injection | |
Emissions standard | Euro 2 | |
Compression ratio | 10.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Chain (single-row) | |
Oil type | SAE 10W-40 mineral or semi-synthetic | |
Dry weight | 215 kg |
The BMW M30 B34 (346KA) was used across BMW's E32 and E34 platforms with longitudinal mounting. This engine received platform-specific adaptations—different intake manifolds in the E32 and revised exhaust routing in the E34—and from 1990 the high-compression variant with modified camshaft for improved efficiency. All adaptations are documented in OEM technical bulletins.
The M30 B34 (346KA)'s primary reliability risks are cooling system leaks and ignition component wear at high mileage. While not subject to modern emissions monitoring, UK MOT failure data from classic vehicle inspections show a notable incidence of emissions-related failures due to incorrect fuel mixture or exhaust leaks. Long-term storage and use of modern ethanol-blended fuels increase the risk of fuel system degradation, making proper maintenance and fuel selection critical for preservation.
Analysis derived from BMW technical documentation (1988–1995) and UK MOT failure statistics for classic vehicles (2018–2023). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The M30 B34 (346KA) is highly reliable when properly maintained. Its simple mechanical design and robust construction make it one of BMW's most durable engines. Common issues like intake manifold leaks and distributor wear are manageable with routine care. With regular oil changes, coolant service, and valve adjustments, these engines can exceed 200,000 km with minimal major repairs.
The most common issues are intake manifold gasket coolant leaks, distributor cap and rotor wear, cooling system failures (radiator, thermostat), and fuel injector clogging. These are well-documented in factory service literature and are largely preventable with proper maintenance, use of quality fuel, and regular inspection of ignition and cooling components.
This 3.4L petrol was used in the BMW 5 Series (E34: 530i/535i, 1988–1995) and 7 Series (E32: 730i/735i, 1988–1995). All applications feature longitudinal engine mounting and were built to meet Euro 2 emissions standards.
Yes, the M30 B34 responds well to classic tuning. Common upgrades include performance camshafts, exhaust headers, and upgraded intake manifolds. With these modifications, outputs of 230–250 PS are achievable. High-compression pistons and performance ignition systems can further enhance performance. Tuning should respect the engine's mechanical limits, particularly the stock crankshaft and connecting rods.
Moderate for its era. In a BMW 535i (E34), real-world consumption averages 13.0–16.0 L/100km (18–22 mpg UK) on mixed driving. Highway efficiency can reach ~12.0 L/100km (~23 mpg UK). Actual economy depends on driving style and engine condition, but it offers a good balance of performance and efficiency for a naturally aspirated inline-six engine.
No. The M30 B34 is a non-interference engine. If the timing chain fails or jumps, piston-to-valve contact will not occur, preventing catastrophic internal damage. This design feature enhances its reliability and makes it a popular choice for restorers and classic car enthusiasts.
BMW originally specified SAE 10W-40 mineral or semi-synthetic oil. Modern high-quality mineral or semi-synthetic oils meeting this viscosity are suitable. Oil should be changed every 10,000–15,000 km or annually to ensure proper lubrication of the timing chain and valvetrain.
Comprehensive technical documentation and regulatory references
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Regulation (EC) No 715/2007
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