BMW M54B25

The BMW M54B25 is a 2.5 liters (2,494 cc, 152.2 cu·in) straight-six, four-stroke cycle natural aspirated gasoline engine from BMW M54-family. The engine was manufactured on Munich Plant (Munich, Germany) from 2000 to 2006.

The BMW M54B25 engine features a cast-aluminum alloy cylinder block with cast-iron cylinder liners. The aluminum cylinder head uses chain-driven double overhead camshafts (DOHC) and four valves per cylinder (24 valves in total). It is equipped with a Siemens MS 43 engine management system, dual VANOS (Variable Valve Timing System from BMW) for both inlet and exhaust camshafts, fully electronic throttle without mechanical backup, dual length intake manifold (called “DISA” by BMW), a distributorless ignition system with individual ignition coils for each cylinder and an electronically controlled thermostat.

It has an 84.0 mm (3.31 in) cylinder bore and 75.0 mm (2.95 in) piston stroke. Compression ratio rating is 10.5:1. The M54B25 engine produced 192 PS (141 kW; 189 HP) at 6,000 rpm of maximum horsepower and 245 N·m (25 kg·m, 180.6 ft·lb) at 3,500 rpm of peak torque.

The breakdown of the engine code is as follows:

• M54 – Engine Family
• B – Gasoline
• 25 – 2.5 Liter Displacement

General information

Cylinder block

The M54B25 engine used cast aluminum alloy cylinder block with cast-iron cylinder liners, bore is 84.0 mm (3.31 in) and the piston stroke is 75.0 mm (2.95 in). The compression ratio rating is 10.5:1. The cylinders are exposed on all sides to circulating coolant. The cast-iron counterweighted crankshaft rotates in replaceable split-shell main bearings. This engine used seven main bearings.

The forged steel connecting rods use replaceable split-shell bearings at the crankshaft end and solid bushings at the piston pin end. The pistons are of the three-ring type with two upper compression rings and a lower one-piece oil scraper ring. Full-floating piston pins are retained with circlips.

Cylinder head

The cylinder head is made of an aluminum alloy with good cooling efficiency. The M54B25 engine uses chain-driven double overhead camshafts and four valves per cylinder. Standart head height is 140.0 mm (5.5118 in). The cylinder head employs a crossflow design for greater power and efficiency. Intake air enters the combustion chamber from one side while exhaust gasses exit from the other. This engine is equipped with dual VANOS (Variable Camshaft Timing) system. VANOS is fully variable and operates independently on both intake and exhaust sides.

Intake valves are 33.0 mm (1.2992 in) in diameter and exhaust valves are 30.5 mm (1.2008 in). They have a duration of 228° for inlet and 244° for exhaust valves, valve lift is 9.0 mm (0.3543 in) for both intake and exhaust valves. Valve clearance is set by self-adjusting (zero-lash) hydraulic lifters for reduced valve noise and the elimination of routine valve adjustment.

Head tightening procedure and torque specs:

• Step 1: 40.0 Nm; 4.1 kg·m; 29.5 ft·lb
• Step 2: Turn all bolts 90°
• Step 3: Turn all bolts another 90°

Maintenance data

Vehicle applications

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