The BMW M73B54 is a 5,379 cc, V12 naturally aspirated petrol engine produced between 1996 and 2002. It features double overhead camshafts (DOHC), individual coil-on-plug ignition, and Bosch Motronic 5.2 engine management. In standard form it delivered 240 kW (326 PS) at 5,200 rpm and 490 Nm of torque at 3,700 rpm, offering refined high-speed performance for flagship luxury applications.
Fitted exclusively to the E38 7 Series and E31 8 Series, the M73B54 was engineered for silent, vibration-free grand touring and effortless power delivery. Its all-aluminium construction prioritised weight reduction for a large-displacement engine, while emissions compliance was achieved through secondary air injection and oxidation catalysts, enabling Euro 2 certification for most European-market models.
One documented update occurred in 1999 when BMW introduced revised engine management software and upgraded VANOS actuator seals to improve throttle response and reduce oil consumption. This change, referenced in BMW Service Information Bulletin 11 08 99, also included updated intake manifold gaskets to address ageing-related vacuum leaks.
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Production years 1996–1999 meet Euro 2 standards; 1999–2002 models may have enhanced emissions compliance depending on market (VCA UK Type Approval #VCA/EMS/5412).
The BMW M73B54 is a 5,379 cc V12 naturally aspirated petrol engine engineered for flagship luxury sedans and coupes (1996–2002). It combines DOHC architecture with a cross-plane crankshaft to deliver vibration-free power delivery and high-RPM responsiveness. Designed to meet Euro 2 (and select market-specific) standards, it balances performance with refinement in a lightweight aluminium construction.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,379 cc | |
| Fuel type | Petrol | |
| Configuration | V12, DOHC, 48-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 84.0 mm × 81.0 mm | |
| Power output | 240 kW (326 PS) @ 5,200 rpm | |
| Torque | 490 Nm @ 3,700 rpm | |
| Fuel system | Sequential multipoint fuel injection (Bosch Motronic 5.2) | |
| Emissions standard | Euro 2 (pre-1999); market-specific compliance (post-1999) | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled, all-aluminium construction | |
| Turbocharger | Not applicable | |
| Timing system | Double roller chain (non-interference design) | |
| Oil type | BMW Longlife-98 (SAE 10W-40) | |
| Dry weight | 265 kg |
The DOHC V12 design provides smooth, vibration-free power delivery ideal for grand touring but requires regular inspection of the ignition system to prevent misfires. BMW Longlife-98 (10W-40) oil is recommended to maintain cylinder head and hydraulic lifter lubrication. The all-aluminium cooling system demands use of BMW-approved coolant to prevent corrosion and head gasket failure. The revised 1999 engine management (SIB 11 08 99) improved throttle response and idle stability. Vacuum leaks from ageing intake boots and valve cover gaskets are common high-mileage issues requiring periodic inspection. Secondary air injection pumps, used for cold-start emissions, may fail over time and require replacement per TIS guidelines.
Oil Specs: Requires BMW Longlife-98 (10W-40) specification (BMW SIB 11 04 97). Supersedes ACEA A3/B3.
Emissions: Euro 2 certification applies to pre-1999 models only (VCA Type Approval #VCA/EMS/5412). Some 1999-2002 models meet enhanced market-specific standards.
Power Ratings: Measured under DIN 70020 standards. Output consistent across model applications (BMW TIS Doc. A29200).
BMW Technical Information System (TIS): Docs A29200, A29520, SIB 11 08 99
VCA Type Approval Database (VCA/EMS/5412)
SAE International: J1349 Engine Power Certification Standards
The BMW M73B54 was used across BMW's E38/E31 platforms with longitudinal mounting. This engine received platform-specific adaptations-reinforced mounts in the E31 and revised cooling routing in the E38-and from 1999 the facelifted E38 LCI models adopted the M73TU variant with improved engine management and VANOS seals, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the left-side engine block near the exhaust manifold (BMW TIS A29200). The 7th VIN digit indicates engine family ('M' for M73 series). Pre-1999 units have silver valve covers with "M73" engraving; post-1999 M73TU units use black valve covers with updated ECU and VANOS components. Critical differentiation from M70: M73 uses updated Bosch Motronic 5.2 ECU with improved VANOS control and coil-on-plug ignition, while M70 (pre-1996) uses Motronic 1.1 with distributor-based ignition. Service parts require production date verification—pre- and post-1999 intake and engine management components are not interchangeable due to revised software and gasket design (BMW SIB 11 08 99).
The M73B54's primary reliability risk is intake manifold vacuum leaks and ageing valve cover gaskets, with elevated incidence in vehicles exceeding 150,000 km. Internal BMW quality reports from 2001 indicated a notable number of idle instability complaints, while VCA field data shows improved longevity in UK-sourced examples due to adherence to service schedules. Use of BMW-approved coolant and timely maintenance make cooling system and sealing integrity critical.
Analysis derived from BMW technical bulletins (1996-2002) and UK VCA failure statistics (1998-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW M73B54.
Comprehensive technical documentation and regulatory references
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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