BMW M21D24

BMW M21D24The BMW M21D24 is a 2.4 liters (2,443 cc, 149.1 cu-in) straight-six, four-stroke cycle naturally aspirated or turbocharged diesel engine from BMW M21-family. This engine is based on the M20 gasoline engine. The engine was manufactured on Steyr Plant (Upper Austria) since 1983 to 1992.

The BMW M21D24 engine features a cast-iron block and aluminum head with a single overhead camshaft (SOHC) and two valves per cylinder (12 in total). It has swirl chamber injection. Cylinder bore and piston stroke are 80.0 mm (3.15 in) and 81.0 mm (3.19 in), respectively. Compression ratio rating is 22.0:1.

An early version of this engine was turbocharged. It used the Garrett T03 turbocharger (without an intercooler) and mechanically controlled fuel pump. This engine produced 115.6 PS (85.0 kW; 114.0 HP) at 4,800 rpm of output power and 210 N·m (21.4 kg·m, 154.8 ft·lb) at 2,400 rpm of torque. Since 1987, the M21D24 engine was equipped with an electronically controlled fuel pump (BoschEDC management system), which increased the torque to 220 N·m (22.4 kg·m, 162.4 ft·lb) at 2,400 rpm.

In 1985, BMW introduced the naturally aspirated version of the M21D24, which produces 85.7 PS (63.0 kW; 85.0 HP) at 4,600 rpm of horsepower and 152 N·m (15.5 kg·m, 112 ft·lb) at 2,500 rpm of peak torque.

The breakdown of the engine code is as follows:

  • M21 – Engine Family
  • D – Diesel
  • 24 – 2.4 Liter Displacement

General information

Engine Specifications
Engine codeM21D24
LayoutFour stroke, Inline-6 (Straight-6)
Fuel typeDiesel
Displacement2.4 L, 2,443 cc (149.1 cu in)
Fuel system Before 1987: Mechanically controlled fuel pump
After 1987: Electronically controlled fuel pump (BoschEDC)
Power adderGarrett T03 turbocharger
Max. horsepower Naturally aspirated:
85.7 PS (63.0 kW; 85.0 HP) at 4,600 rpm
115.6 PS (85.0 kW; 114.0 HP) at 4,800 rpm
Max. torque Naturally aspirated:
152 N·m (15.5 kg·m, 112 ft·lb) at 2,500 rpm
210 N·m (21.4 kg·m, 154.8 ft·lb) at 2,400 rpm
220 N·m (22.4 kg·m, 162.4 ft·lb) at 2,400 rpm
Firing order1-5-3-6-2-4
Dimensions (L x H x W):

Cylinder block

Cylinder block
Cylinder block alloyCast-iron
Compression ratio:22.0:1
Cylinder bore:80.0 mm (3.15 in)
Piston stroke:81.0 mm (3.19 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:7
Cylinder inner diameter (standard):80.000 mm (3.1496 in)
Piston skirt diameter (standard):79.965 mm (3.1482 in)
Piston ring side clearance:Top
Second0.050-0.080 mm (0.002-0.0031 in)
Oil0.030-0.060 mm (0.0012-0.0024 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)
Oil0.250-0.500 mm (0.0098-0.0197 in)
Crankshaft journal diameter:60.000 mm (2.3622 in)
Crankpin diameter:44.975-44.991 mm (1.7707-1.7713 in)

Cylinder head

Cylinder head
Valve Arrangement:SOHV, belt drive
Valves:12 (2 valves per cylinder)
Intake/Exhaust duration:
Valve head diameter:INTAKE35.000 mm (1.378 in)
EXHAUST31.000 mm (1.2205 in)
Valve steam diameter:INTAKE7.000 mm (0.2756 in)
EXHAUST7.000 mm (0.2756 in)

Maintenance data

Valve clearance
Intake valve (HOT)0.35 mm (0.0138 in)
Exhaust valve0.35 mm (0.0138 in)
Compression pressure
Minimum20.4 kg/cm2 (20.0 bar, 290 psi)
Oil system
Recommended engine oil5W-30, 10W-30
Oil typeSemi-synthetic
Engine oil capacity (Refill capacity)5.8 L (6.13 US. qt, 5.1 Imp. qt.)
Ignition system
Glow plugBosch 0 205 201 008, Champion CH159, Lucas/CAV HDS218

Vehicle applications

ModelYears Produced
BMW 524td (E28)1983-1988
BMW 524d (E28)1985-1988
BMW 524td (E30)1985-1993
BMW 524d (E30)1985-1993
BMW 524td (E34)1988-1991
Continental Mark VII1984-1985
Lincoln Continental1984-1985
Vixen 21 TD and Vixen 21 XC1986-1987
Bertone Freeclimber1989 – 1991
UMM Alter II1992
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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