The N52B25 is a 2.5-liter engine from the new N52 series (which includes the N52B30), with six cylinders in line. The N52B25 was introduced in 2005 as a replacement for the popular M54B25 and unlike past evolutions of the M-family, this is now a completely new engine. The N52 is based on an even lighter magnesium-aluminum cylinder block, with a new lightweight connecting rod and piston group and a redesigned crankshaft.
The N52B25 uses an updated cylinder head with the already familiar system for changing the valve timing on two shafts, or more simply, Double-VANOS. In addition, a Valvetronic valve lift change system was added, which increased output and fuel efficiency. The timing drive uses a chain, a DISA variable-length manifold is used at the inlet, the nozzles are installed in the cylinder head, the Siemens MSV70 engine management system.
This motor was used on BMW cars with the index 23i and 25i.
Specifications
| Production years | 2005-2011 |
| Displacement, cc | 2497 |
| Fuel system | injector |
| Power output, hp | 177 – 218 |
| Torque output, Nm | 230 – 250 |
| Cylinder block | aluminum R6 |
| Block head | aluminum 24v |
| Cylinder bore, mm | 82 |
| Piston stroke, mm | 78.8 |
| Compression ratio | 11.0 |
| Features | Valvetronic, DISA |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | double VANOS |
| Turbocharging | no |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 6.5 |
| Fuel type | petrol |
| Euro standards | EURO 4/5 |
| Fuel consumption, L/100 km (for E60 523i) — city — highway — combined |
12.1 6.4 9.3 |
| Engine lifespan, km | ~250 000 |
Disadvantages of the N52B25 engine
The main problems of the N52B25 engine are: increased oil consumption, ticking sounds, floating revs.
High oil consumption is usually associated with oil scraper rings. They are very thin and coke quickly enough. The reason may be in the valve stem seals. The problem appears even before reaching the mark of 100 thousand kilometers. The condition of the system should be checked regularly and the rings and caps should be replaced. It is also recommended to check the condition of the crankcase ventilation valve.
If you do not pay attention to the high oil consumption, the existing problem will lead to clogging of the catalysts. In this case, it will be necessary to supply new catalysts, which will be expensive, or use inexpensive flame arresters.
When a ticking sound is heard in the engine, these are features of power units manufactured before 2009. This does not pose any danger to the unit.
Floating revolutions occur due to a breakdown of the Valvetronic system, Vanos valves or a flow meter. If not properly maintained, the Vanos system can lead to problems. System failure is usually caused by the use of low-quality working fluids. To restore system operation, a flush is performed. If the problem persists, a replacement is required.
If the engine overheats, check the condition of the cooling system, pump, cleanliness of the radiator. The pump needs to be changed every 100 thousand kilometers. The oil recommended by the manufacturer should be used.
