The BMW N52 B25 A is a 2,497 cc, inline — six naturally aspirated petrol engine produced between 2004 and 2011. It featured dual overhead camshafts (DOHC), 24 — valve configuration, and BMW's Valvetronic III system with double VANOS variable valve timing. In standard tune, it delivered 140 kW (190 PS) and 245 Nm of torque, offering smooth throttle response and refinement for compact and mid — size applications.
Fitted to models including the E90 3 Series and E60 5 Series, the N…
Production years 2004–2011 meet Euro 4 emissions standards .
The BMW N52 B25 A is a 2,497 cc inline-six naturally aspirated petrol engine engineered for compact and mid-size platforms (2004–2011). It combines Valvetronic III with double VANOS to deliver precise throttle control and smooth power delivery. Designed to meet Euro 4 standards, it balances efficiency with responsiveness in BMW's mid-range petrol strategy.
| 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 | 245 Nm @ 3,000 rpm | |
Fuel system | Sequential multipoint fuel injection (SME) | |
Emissions standard | Euro 4 | |
Compression ratio | 10.7:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Double-row roller chain (DOHC) | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 172 kg |
The BMW N52 B25 A was used across BMW's E90/E60 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-increased cooling capacity in the E60 5 Series and revised intake manifolds in the E90 3 Series-and from 2007 the updated timing chain guide system with improved oil flow, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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The N52 B25 A is mechanically robust with good longevity when properly maintained. Early models (2004-2007) are prone to timing chain wear, but post-2007 revisions resolved this with improved guides and tensioner design. Regular oil changes (every 15,000 km), use of correct BMW Longlife-01 oil, and attention to Valvetronic system ensure long-term reliability. The strong inline-six architecture supports high mileage with minimal wear when serviced correctly.
Primary issues include timing chain wear (especially pre-2007), Valvetronic motor faults, VANOS solenoid failures, and coolant leaks from the expansion tank. These are well-documented in BMW service bulletins and stem from component aging, thermal stress, and maintenance neglect. The 2007 timing chain update significantly improved system durability.
The N52 B25 A was used in the E90 3 Series (320i, 323i), E60 5 Series (520i, 523i), and E83 X3 (2.5i). It was part of BMW's naturally aspirated six-cylinder strategy, offering balanced performance in compact and mid-size models. No licensed applications outside BMW. The engine was succeeded by the N53 and later N20 engine families.
Yes. The N52 B25 A responds well to ECU remapping, with safe gains of +20-30 PS achievable on stock hardware. Aftermarket upgrades like performance intakes and exhausts allow modest increases. The robust inline-six bottom end supports moderate tuning without internal modifications. Enthusiasts often pair ECU tuning with intake and exhaust modifications for improved throttle response.
In combined driving, expect 8.5–10.0 L/100km (33–28 mpg UK). Highway cruising can achieve ~7.0 L/100km (~40 mpg UK), while city driving may exceed 12.0 L/100km (23 mpg UK). Real-world figures depend on driving style and vehicle weight, with E83 models generally less efficient than E90. The engine's smoothness contributes to relaxed motorway efficiency.
Yes. The N52 B25 A is an interference engine. If the timing chain fails or skips, pistons will contact open valves, causing catastrophic internal damage. While the double-row roller chain is durable, any signs of rattle or tensioner wear should be investigated immediately to prevent engine seizure. Regular oil changes help maintain chain tensioner function and lubrication.
BMW specifies SAE 5W-30 oil meeting BMW Longlife-01 standard. Use a high-quality synthetic designed for petrol engines. Change oil every 15,000 km or annually to protect the timing chain, Valvetronic system, and VANOS. Proper lubrication is essential for long-term reliability, especially under sustained load or high-temperature operation.
Comprehensive technical documentation and regulatory references
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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
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