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M51 Motor.JPG
Manufacturer BMW
Production 1991-2000
Combustion chamber
Configuration Inline-6
Displacement 2497 cm3
Cylinder bore 80 mm
Piston stroke 82,8 mm
Cylinder block alloy Cast iron
Valvetrain OHC
Compression ratio 22:1
Turbocharger Single turbocharger, tds-engines also have an intercooler
Fuel system Swirl-chamber-injection
Management Bosch DDE 2.1
Fuel type Diesel
Cooling system Water-cooled
Power output 85-105 kW
Torque output 222-280 N·m
Dry weight 132 kg
Predecessor BMW M21
Successor BMW M57

The BMW M51 is an inline diesel engine produced by the upper austrian BMW plant in Steyr from July 1991 through February 2000. Its predecessor is the BMW M21, the successor is the BMW M57.


The M51 is a water-cooled and turbocharged inline six-cylinder diesel engine with a Bosch VP20-swirl-chamber-injection.[1][2] Some engine variants have an intercooler in addition to the turbocharger, they can be identified by the tds.[2] The M51 is an engine made of cast iron, it has one chain driven overhead camshaft[3] and two valves per cylinder.[2][3] Compared to the M21 the M51 has now tappets and a hydraulic valve lash adjustment.[2] The fuel injection in the first engines is controlled by the ECU Bosch DDE 2.1, which was replaced after the first technical revision by the DDE 2.2.[3] This results in greater torque at lower revs.[3] For lubrication SAE 5W-40 oil is used.[4]

Engine Bore × Stroke Displacement Power at min−1 Torque at min−1 Compression Year
M51D25 UL 80 × 82,8 mm 2497 cm3 85 kW at 4800 222 Nm at 1900 22:1 1991–1997
M51D25 OL[3] 105 kW at 4800 260 Nm at 2200 1991–1996
X25DT[5][A 1] 96 kW at 4800 250 Nm at 1400 1994–2001
M51D25TÜ UL 85 kW at 4800 230 Nm at 1900 1996–1998
M51D25TÜ OL[3] 105 kW at 4800 280 Nm at 2200 1996–1998
M51D25TÜ OL[3] 105 kW at 4600 1998–2000
M51D25M1[6][A 2] 100 kW at 4400 270 Nm at ? until 1999
  1. ^ For Opel Omega B only
  2. ^ For Range Rover DSE 2.5 P38 LP2 only


See also[edit]

External links[edit]


  1. ^ BMW E38 7 Series 725 tds Technical data
  2. ^ a b c d Die BMW-Sportdiesel: Von 524td E28 über 530d E39 bis BMW M550d F10 (german)
  3. ^ a b c d e f g Etzold: So wird's gemacht: pflegen – warten – reparieren. Band 102, BMW 5er E39 Delius Klasing Verlag. Pages 12 and 13 (german)
  4. ^ Übersicht der Motorölqualitäten. Page 7 (german)
  5. ^ Opel Omega B 2.5 TD 96 kW 130 PS - Motor: 25DT, X25DT, X25TD - Eco Optimierung / Leistungssteigerung (german)
  6. ^ Automobile Catalogue: 1997 Range Rover 2.5 DSE (model for Europe ) specifications & performance data review.