M54B25 2.5L engine from BMW - the most important information in one place

Cars equipped with the M54B25 engine are still present on Polish roads. This is a successful engine, which is rated as an economical unit that provides optimal performance. We present the most important information about the technical characteristics, design solutions and failure rates of BMW products.

M54B25 engine - technical data

Model M54B25 is a 2.5-liter gasoline unit - exactly 2494 cm3. It was created in an inline six. The four-stroke naturally aspirated engine is a member of the M54 family. Produced from 2000 to 2006 at the Bavarian BMW plant in Munich.

The block has a bore diameter of 84,0 mm and a stroke of 75,00 mm. The nominal compression ratio is 10,5:1, the maximum power of the unit is 189 hp. at 6000 rpm, peak torque - 246 Nm.

It is also worth mentioning what exactly the symbols of individual units mean. M54 refers to the engine family, the B symbol to the petrol version of the engine, and 25 to its exact power.

What machines were installed M54B25?

The unit was used from 2000 to 2006. The BMW engine was installed on such cars as:

• BMW Z3 2.5i E36/7 (2000–2002);
• BMW 325i, 325xi, 325Ci (E46) (2000–2006 gg.);
• BMW 325ti (E46/5) (2000–2004 gg.);
• BMW 525i (E39) (2000–2004);
• BMW 525i, 525xi (E60/E61) (2003–2005 gg.);
• BMW X3 2.5i (E83) (2003-2006);
• BMW Z4 2.5i (E85) (2002-2005).

Drive design

The M54B25 engine was based on an aluminum alloy cast cylinder block and cast iron cylinder liners. The cylinder head, also made of aluminum, has chain-driven DOHC double camshafts as well as four valves per cylinder, for a total of 24 valves.

The designers of the power unit also decided to equip it with a Siemens MS 43 control system and Vanos dual variable valve timing for the intake and exhaust camshafts. The full name of this system is the BMW variable valve timing system. All this is complemented by a non-mechanical electronic throttle and a double-length DISA intake manifold.

In the case of the M54 B25 engine, a distributionless ignition system with ignition coils was also used. Each of them is designed separately for each cylinder and thermostat, the operation of which is controlled by electronics.

Block architecture

This element has cylinders, each of which is exposed to a circulating coolant. The balanced cast iron crankshaft rotates in replaceable main bearings with a split housing. It should also be noted that the M54B25 has seven main bearings.

Another highlight is that the forged steel connecting rods use replaceable split bearings on the crankshaft side, as well as solid bushings where the piston pin is. The pistons themselves are a three-ring design with two upper compression rings and a one-piece lower ring that wipes out the oil. Piston pins, on the other hand, hold their position through the use of circlips.

cylinder cover

For the M54B25 cylinder head, the material of manufacture is decisive. The aluminum alloy provides good cooling efficiency parameters. In addition, it is created on the basis of a cross-country design that provides more power and economy. It is thanks to him that the intake air enters the chamber from one side and exits from the other.

Special design measures have also led to a reduction in engine noise. This applies to valve clearance, which is regulated by self-adjusting hydraulic lifters. It also eliminates the need for regular valve adjustments.

Drive operation - what to look for?

In the case of the BMW M54B25 engine, the most common problems are a faulty water pump and a faulty thermostat. Users also point to a damaged DISA valve and broken VANOS seals. The valve cover and oil pump cover also often fail.

Is the M54B25 engine worth recommending?

During its heyday, the M54B25 received overwhelmingly positive reviews. He regularly ranked first in the list of the best engines in the world of Ward magazine. With regular maintenance and a timely response to frequently failing components, the M54B25 engine will operate without fail for thousands of kilometers.