The BMW N52 B25 B is a 2,497 cc, inline — six naturally aspirated petrol engine produced between 2005 and 2011. It features DOHC, 24 — valve configuration, and BMW's Valvetronic III variable valve lift system, delivering 140 kW (190 PS) and 235 Nm of torque. Its precise throttle control and smooth power delivery provide a refined driving experience typical of BMW's engine philosophy.
Fitted to the E90 3 Series, E60 5 Series, and E70 X5, the N52 B25 B was engineered for balanced p…
All production years 2005–2011 meet Euro 4 emissions standards .
The BMW N52 B25 B is a 2,497 cc inline-six naturally aspirated petrol engine engineered for executive and compact luxury platforms (2005–2011). It combines Valvetronic III variable valve lift with dual overhead camshafts to deliver smooth power delivery and improved fuel efficiency. Designed to meet Euro 4 standards, it balances performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,497 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 82.0 mm × 78.8 mm | |
Power output | 140 kW (190 PS) @ 6,100 rpm | |
Torque | 235 Nm @ 2,500–4,000 rpm | |
Fuel system | Bosch Motronic ME7.2 sequential port fuel injection | |
Emissions standard | Euro 4 | |
Compression ratio | 10.7:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Double-row timing chain | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 175 kg |
The BMW N52 B25 B was used across BMW's E90, E60, and E70 platforms with longitudinal mounting. This engine received platform-specific adaptations-integrated Valvetronic on all units-and from 2011 the facelifted E90 LCI adopted the N53B30 variant with direct injection, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from manufacturer technical service bulletins and industry workshop records. 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 N52 B25 B offers smooth performance and solid engineering, but early models (2005–2008) are prone to timing chain guide wear. Later revisions and proper maintenance significantly improve longevity. Regular cooling system service, use of correct oil (5W-30 BMW Longlife-01), and prompt attention to cold-start rattles are essential for reliability.
Key issues include timing chain guide wear (especially pre-2008), cooling system failures (thermostat, water pump), vacuum leaks from intake hoses, and oil leaks from valve cover and rear main seal. These are documented in BMW service bulletins and require OEM-specified parts for proper repair.
The N52 B25 B was used in the E90 3 Series 325i (2005–2011), E60 5 Series 525i (2005–2010), and E70 X5 3.0si (2006–2010). It was replaced by the N53B30 in 2011 with direct injection and updated engine management. No cross-manufacturer applications are documented for this variant.
Aftermarket ECU tuning is common on the N52B25B platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.
In an E90 325i, combined consumption is ~8.5 L/100km (33 mpg UK). City driving may see 10–11 L/100km (28–26 mpg), while highway cruising can achieve ~6.8 L/100km (41 mpg). Real-world figures depend on driving style and vehicle condition.
Yes. The N52 series is an interference engine. If the timing chain fails or jumps, pistons can contact open valves, causing severe internal damage. Chain maintenance and tensioner inspection are critical, especially given the engine's high-RPM operation.
BMW specifies 5W-30 synthetic oil meeting BMW Longlife-01 spec. Change intervals should not exceed 15,000 km. Proper oil ensures adequate protection for camshafts, lifters, and the timing chain, especially under sustained high-RPM use.
Comprehensive technical documentation and regulatory references
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Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
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.
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