BMW N54B25OL engine

The BMW N54B25OL (2000-2006) is an inline gasoline internal combustion engine. Manufactured for the BMWX5 (E53), it replaces the M52 engine.

In 2002 and 2003, it became one of the greatest engines, according to the list of top 10 best engines. The BMW S54 is the identical high-performance engine used for the E46 M3, Z4 M and Z3 MCoupe / Roadster. The BMWM56 SULEV is based on the M54, whose production was phased out after the launch of the N52 in 2004.

The M54B25 is one of the best-known engines in the M54 series, which began construction in 2000 and seems to be a great replacement for the M52TUB25. This series is also known by the M54B22, M54B30 and S54B32 models. M54B25 and M54B30. These powerplants differ in their placement under the hood, as they have different crankshafts that connect the pistons and connecting rods. Many other parts differ at the same time, including intake manifolds, injectors, camshafts, throttles, and ECUs.

Engine specifications N54B25OL

Advantages

The aluminum cylinder block of the latest engine is equipped with cast iron cylinders. The crankshaft is made of the same material. It also has longer connecting rods than the earlier version, which are 145 mm long. Meanwhile, the latest version of the engine has lighter pistons.

Another similar feature is the dual VANOS cylinder head. The newer engine has a 10 mm shorter intake manifold. The motor’s increased power is achieved through wide ports and ducts. In addition, the engine is equipped with electronic throttle control and SiemensMS43 / SiemensMS45 / SiemensMS45.1 electronic control unit.

The N54B25OL was mainly used for BMW 25i series cars.

Unfortunately, the engine proved to be uncompetitive with later variations of the engine released in 2005-2006.

Disadvantages

• Rapid engine oil consumption. Being the main drawback of another engine, the M52TU, it leads to carbonization of the piston rings. It is necessary to buy new piston rings. M52TUB28 elements are suitable. It is also advisable to check the crankcase ventilation valve (PCV).
• The motor is overheating. The problem is quite common with six-cylinder engines. You should inspect the radiator and make sure it is free of dirt. We also recommend checking for oxygen in the cooling system, as this can also cause overheating. If you still have overheating problems, pay attention to the condition of the thermostat, radiator cap and pump.
• Problems with cold start. This trouble is not uncommon with the M52TU either. Buying new hydraulic lifters will avoid carbonization.
• Oil Pressure. We recommend inspecting the oil filter housing or oil pump, as the problem may be related to their malfunction.
• In addition, another common problem is the failure of the camshaft position sensor. You may also have problems with thermostat wear and tear and engine oil requirements being too high. However, M54 engines are considered to be more efficient than M52 engines.

Technical specifications

The specifications of the BMW N54B25 and N54B25OL powerplants are not radically different in the N52 series. This is the next generation of engines, which has six cylinders, but it has received a number of corrections of shortcomings.

These are in-line power units that operate thanks to the Valvetronic fuel delivery system. Serial production of these power units began simultaneously in February 2015. And was intended for BMW X3 crossovers.  This installation stood also on the BMW fifth series . But later, a more powerful variant of the M60 began to be installed on the X3. The last year of the engine lineup occurred in 2011, when Bavaria Motors officially announced the cessation of production of contract models and original components.

Let’s talk about the technical specifications. This powertrain is an inline 6-cylinder engine. Useful volume is 2.5 liters in an aluminum housing with aluminum-magnesium inserts. This significantly increased the operational life and reliability of the car. As for the changes, in BMW N54B25 and N54B25OL Germans have changed the architecture of crankshafts.

The changes were aimed at reducing the overall weight. The cylinder head also underwent certain changes due to the introduction of a modernized control system. The main difference was in the uniform fuel supply to the cylinders. Another feature was the installation of a developed manifold, which had a variable length.

On specific specifications: the engine had six cylinders. 4 valves on each of them. The piston stroke was 78. 8 mm and the cylinder diameter was 82 mm. The fuel was compressed with a degree of 11 units, and the exact volume of the engine was 2497 cubic centimeters. In order to reach the maximum 218 horsepower, the driver needs to accelerate the powerplant to 6500 rpm.

As for torque, the engine is capable of producing 250 Newtons per meter at 3,000 rpm. The main feature of these engines is and stable operation exclusively on high-octane fuel. In the recommendations of Bavaria Motors company it is written mandatory requirement for fuel with octane number not lower than 95.

Otherwise, detonations and a significant reduction in the life of the powertrain are possible. The engine lineup meets the Euro-5 standard, and the average consumption in the mixed cycle is about 10 liters per 100 kilometers of mileage. In order not to jam the engine, it is necessary to fill 6.5 liters of oil and change the technical fluid every 12,000 km or after 2 years of operation.

Tuning

More often than not, this engine is converted to a three-liter engine to increase power.

To do this you need to replace the crankshaft, connecting rods, injectors, ECU and entire intake with parts from the M54V30.This way you can increase the power to about 230hp.

Using the ESS compressor kit will increase engine output to 300 “horses” on standard pistons. All would be good, but the price of this modification discourages many owners of M52 engines.

This engine is installed on the following models:

BMW 5-Series (E61)