The BMW M30 B34 (346KB) is a 3,430 cc, inline-six naturally aspirated petrol engine introduced in 1988 as part of BMW's long-running M30 engine family. It features a cast-iron block, aluminium head, single overhead camshaft (SOHC), and Bosch Motronic 1.3 electronic fuel injection. In standard tune it delivers 160–170 kW (218–231 PS), with torque output of 310 Nm, offering smooth and refined performance typical of BMW's inline-six heritage.
Fitted across BMW's E32 and E34 platforms, the M30 B34 (346KB) was engineered for longitudinal mounting and rear-wheel drive layouts. Emissions compliance was achieved through catalytic converter systems, meeting Euro 1 standards from 1988. The engine is renowned for its durability and mechanical simplicity, supporting decades of enthusiast ownership and restoration.
One documented concern is fuel injector clogging and airflow meter drift in older units due to aging components and modern fuel chemistry. This issue, referenced in BMW Service Information Bulletin 13 10 89, is linked to varnish buildup in Motronic injectors and degraded airflow sensor seals. From 1990, BMW revised fuel system calibration and introduced improved sealing components to enhance long-term reliability.
All production years 1988–1995 meet Euro 1 emissions standards (VCA UK Type Approval #VCA/EMS/7899).
The BMW M30 B34 (346KB) is a 3,430 cc inline-six naturally aspirated petrol engine engineered for executive sedans and grand tourers (1988–1995). It combines electronic fuel injection with a smooth inline-six design to deliver linear power delivery and driver engagement. Designed to meet evolving emissions standards, it balances refinement with mechanical reliability and serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,430 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-6, SOHC, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 86.0 mm × 94.6 mm | |
| Power output | 160–170 kW (218–231 PS) @ 5,800 rpm | |
| Torque | 310 Nm @ 4,200 rpm | |
| Fuel system | Bosch Motronic 1.3 electronic fuel injection | |
| Emissions standard | Euro 1 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled with mechanical thermostat | |
| Turbocharger | None | |
| Timing system | Chain (single-row, front-mounted) | |
| Oil type | SAE 10W-40 mineral or 5W-40 synthetic | |
| Dry weight | 200 kg |
The M30 B34's Motronic fuel injection system offers improved drivability over L-Jetronic but requires attention to aging sensors and fuel quality. The system is sensitive to vacuum leaks, degraded airflow meters, and clogged injectors, which can cause idle instability and poor fuel economy. Oil changes every 7,500–10,000 km are recommended to maintain chain and bearing longevity. Catalytic converters require unleaded fuel. Timing chain wear is uncommon but possible in neglected engines; inspection is advised during major service. The engine tolerates lower-octane fuel but performs best on 95 RON. Modern ethanol-blended fuels can degrade old rubber components; use ethanol-compatible hoses for long-term reliability.
Oil Specs: No BMW Longlife specification; use high-quality mineral or synthetic 10W-40 meeting API SL/CF standards (BMW SIB 13 10 89).
Emissions: Euro 1 certification applies to all models (1988–1995) (VCA Type Approval #VCA/EMS/7899).
Power Ratings: Measured under DIN 70020 standards. Output varies by model year and market (BMW TIS Doc. A23005).
BMW Technical Information System (TIS): Docs A23000, A23001, A23002, SIB 13 10 89
VCA Type Approval Database (VCA/EMS/7899)
DIN Deutsches Institut für Normung: DIN 70020 Power Measurement Standard
The BMW M30 B34 (346KB) was used across BMW's E32 and E34 platforms with longitudinal mounting and RWD layout. This engine received platform-specific adaptations—revised intake manifolds in the E32 and dual-exhaust setup in performance variants—and from 1990 the facelifted E34 models adopted revised ignition systems, creating interchange limits. No licensed or shared-production partnerships existed for this engine. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front timing cover near the oil filter housing (BMW TIS A23010). The 7th VIN digit indicates engine family ('M' for M-series). All M30 B34 (346KB) units use Bosch Motronic 1.3 with a combined air flow meter and temperature sensor. E32 models (1988–1995) have revised valve covers and intake plumbing. Critical differentiation: This variant is an inline-six with 3.4L displacement and is specific to 534i and 735i models. Service parts are generally interchangeable, but catalytic converter-equipped models require compatible exhaust manifolds.
The M30 B34 (346KB)'s primary concerns are age-related: fuel system degradation, vacuum leaks, and cooling system failures. UK DVLA and MOT records indicate that poorly maintained examples often fail on emissions or idle quality, while well-serviced engines regularly exceed 200,000 km. Cold-start performance and idle stability are most affected by neglected fuel and ignition systems.
Analysis derived from BMW technical bulletins (1980s), UK DVSA MOT failure statistics (2018-2024), and restoration guides. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW M30B34-346KB.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with BMW or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
BMW Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
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
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialBMW documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
