BMW 325i e90 N52b25 Aluminum tapped cover engine
R28,500.00
The BMW N52B25 is a 2.5L naturally aspirated inline six-cylinder petrol engine produced between 2005 and 2011. It is part of the legendary N52 family, which was BMW’s final generation of naturally aspirated straight-six engines before the transition to widespread turbocharging.
Technical Specifications
The N52B25 is distinguished by its innovative magnesium-aluminium composite engine block, which was designed to significantly reduce weight (10 kg lighter than the previous M54) while maintaining structural rigidity.
| Feature | Details |
|---|---|
| Displacement | 2,497 cc (2.5L) |
| Configuration | Inline-6, DOHC, 24 valves |
| Bore x Stroke | 82.0 mm x 78.8 mm |
| Compression Ratio | 11.0:1 |
| Valvetrain | Double-VANOS (VVT) and Valvetronic II (variable valve lift) |
| Induction | Naturally Aspirated with multi-point fuel injection |
Performance Variants
The N52B25 was offered in three main power levels depending on the market and model:
- N52B25U1 (Lower Output): ~174 hp (130 kW) and 230 Nm of torque.
- Standard N52B25: ~201–204 hp (150 kW) and 250 Nm of torque.
- N52B25O1 (Upper Output): ~215–218 hp (160 kW) and 250 Nm of torque.
Common Applications
This engine was primarily used in European and non-North American markets for entry-level “23i” and “25i” models:
- 3 Series (E90/E91/E92/E93): 323i (Canada/Australia/Japan) and 325i (Europe/other).
- 5 Series (E60/E61/F10): 523i and 525i (except US/Canada).
- Z4 (E85/E89): 2.5i, 2.5si, and sDrive23i.
- X3 (E83): 2.5si and xDrive25i.
Reliability & Known Issues
While praised for its smooth power delivery and overall durability, the N52B25 has specific “telltale” maintenance areas:
- Hydraulic Lifter Ticking: Pre-2009 models often develop a distinctive ticking noise during cold starts due to poor oil circulation; BMW revised the cylinder head design in late 2008 to fix this.
- Electric Water Pump: Prone to sudden failure between 80,000–130,000 km.
- Oil Leaks: Common at the valve cover gasket, oil filter housing, and oil pan.
- VANOS Solenoids: Can become clogged or fail, leading to rough idles or power loss.
- Piston Rings: Some B25 variants are known for higher oil consumption due to piston ring wear compared to the larger 3.0L B30 version