BMW M54B25

BMW M54B25The 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

Engine Specifications
Engine codeM54B25
LayoutFour stroke, Inline-6 (Straight-6)
Fuel typeGasoline
Displacement2.5 L, 2,494 cc (152.2 cu in)
Fuel systemFuel injection system
Power adderNone
Max. horsepower192 PS (141 kW; 189 HP) at 6,000 rpm
Max. torque245 N·m (25 kg·m, 180.6 ft·lb) at 3,500 rpm
Firing order1-5-3-6-2-4
Dimensions (L x H x W):
Weight130 kg (286.6 lbs)

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 block
Cylinder block alloyAluminum alloy
Compression ratio:10.5:1
Cylinder bore:84.0 mm (3.31 in)
Piston stroke:75.0 mm (2.95 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:7
Cylinder inner diameter (standard):84.000-84.010 mm (3.3071-3.3075 in)
Piston skirt diameter (standard):83.995 mm (3.3069 in)
Piston pin outer diameter:22.000 mm (0.8661 in)
Piston ring side clearance:Top0.020-0.060 mm (0.0008-0.0024 in)
Second0.020-0.060 mm (0.0008-0.0024 in)
Oil0.015-0.060 mm (0.0006-0.0024 in)
Piston ring end gap:Top0.200-0.400 mm (0.0079-0.0157 in)
Second0.200-0.400 mm (0.0079-0.0157 in)
Oil0.200-0.450 mm (0.0079-0.0177 in)
Crankshaft journal diameter:60.000 mm (2.3622 in)
Crankpin diameter:45.000 mm (1.7717 in)

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.

Cylinder head
Cylinder head alloyAluminum
Valve Arrangement:DOHC, chain driven
Valves:24 (4 valves per cylinder)
Intake/Exhaust duration:228°/244°
Valve head diameter:INTAKE33.0 mm (1.2992 in)
EXHAUST30.5 mm (1.2008 in)
Valve steam diameter:INTAKE6.0 mm (0.2362 in)
EXHAUST6.0 mm (0.2362 in)

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

Compression pressure
Minimum10.0 kg/cm2 (9.9 bar, 145 psi) / 350 rpm
Compression differential limit between cylinders:1.0 kg/cm2 (1.0 bar, 15 psi) / 350 rpm
Oil system
Recommended engine oil SAE 5W-30
Oil typeBMW LL-98 or LL-01
Engine oil capacity (Refill capacity)~ 6.5 L (6.87 US. qt, 5.72 Imp. qt.)
Oil change interval, km (miles)5,000-10,000 (3,000-6,000)
Ignition system
Spark plugBosch: FGR7DQP, NGK: BKR6EQUP
Spark plug torque:25 N·m (2.5 kg·m, 18.4 ft·lb)

Vehicle applications

ModelYears Produced
BMW Z3 2.5i (E36/7 )2000-2002
BMW 325i, 325xi, 325Ci (E46)2000-2006
BMW 325ti (E46/5)2000-2004
BMW 525i (E39)2000-2004
BMW 525i, 525xi (E60/E61)2003-2005
BMW X3 2.5i (E83)2003-2006
BMW Z4 2.5i (E85)2002-2005
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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1 Comment

  1. I am searching for all average data I can normally find via ODB contact to my Icarsoft instrument.
    Like normal value for MAF on idle, O2 sensors when active, ignition timing, misfire and many others Does it exist?

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