BMW M50B20 — 2L Engine
2L · 150 hp
Engine overview
Vehicles with this engine
Factory specifications
Values from the manufacturer documentation for this engine.
Engine (general)
| Engine code | M50 B20 |
| Capacity | 1990 cc |
| Idle speed | 800 ± 75 (-> 09/1990) 700 ± 75 (09/1990 ->) rpm |
| Normal | 10.0 - 11.0 bar |
| Oil pressure | > 0.5 bar/rpm |
| Oil pressure | 4.0 bar/rpm |
| Idle speed | 700 ± 75 rpm |
| Minimum | 8.8 bar |
Engine (petrol)
| Fuel system (make and type) | Bosch Motronic 3.1 (-> 08/1991) Siemens MS40.0 (09/1991 ->) |
| Number of cylinders | 6 |
| Firing order | 1-5-3-6-2-4 |
| Ignition coil resistance, primary | 0.4 ohms |
| Spark plugs (make and type) | Bosch W8LCR |
| Spark plug gap | 0.7 mm |
| Injection pressure/system pressure | 3.0 ± 0.2 bar |
| CO exhaust gas | 0.7 ± 0.5 % |
| Catalytic converter | < 0.5 % |
| CO2 | 13.0 - 16.0 % |
| Catalytic converter | 14.5 - 16.0 % |
| HC | 300 ppm |
| Catalytic converter | 100 |
| O2 | 0.5 - 2.0 % |
| Catalytic converter | 0.1 - 0.5 % |
| Lambda | 0.97 - 1.03 |
| Lambda change (Delta Lambda) | 0.03 |
| Oil temperature during test | 60 °C |
| Fast-idle speed | 2500 - 3000 rpm |
| CO at fast-idle speed | < 0.3 % |
| Closed-loop test at: | 450 - 1150 (-> 09/1990) 350 - 1050 (09/1990 ->) rpm |
| Conditioning catalytic converter | 3 / 3000 min/rpm |
| Conditioning catalytic converter | 4 / 2500 ± 300 min/rpm |
| Fuel system (make and type) | Bosch Motronic M 3.1 (-> 08/1992) DME MS40.1 (09/1992 ->) |
| CO adjustment screw | B |
| Spark plugs (make and type) | NGK BKR6EK Bosch F7LDCR |
| Spark plug gap | 0.7 - 0.8 mm |
| CO exhaust gas | < 0.5 % |
| CO2 | 14.5 - 16.0 % |
| HC | 200 ppm |
| HC | 100 ppm |
| O2 | 0.1 - 0.5 % |
| Closed-loop test at: | 350 - 1050 rpm |
Cooling system
| Cap pressure | 1.8 - 2.1 bar |
| Thermostat opens at | 80 °C |
| Fan on at | 90 °C |
| Thermostat opens at | 80 (-> 08/1992) 88 (09/1992 ->) °C |
Electrical
| Battery | 44 Ah |
| Alternator | 90 A |
| Alternator | 105 A |
| Battery | 55 Ah |
| Alternator | 65 A |
Brakes
| Disc thickness, front | 12.0 mm |
| Disc thickness, front, min. | 10.4 mm |
| Disc thickness (ventilated), front | 22.0 mm |
| Disc thickness (ventilated), front, min. | 20.4 mm |
| Disc thickness, rear | 10.0 mm |
| Disc thickness, rear, min. | 8.4 mm |
| Parking drum lining thickness, min. | 1.5 mm |
| Brake pad thickness, front, min. | 3.0 mm |
| Brake pad thickness, rear, min. | 3.0 mm |
| Disc run-out, max. | 0.01 mm |
| Brake pad thickness, front, min. | 10.4 mm |
| Disc thickness (ventilated), rear, min. | 17.4 mm |
Steering and wheel alignment
| Toe-in, front | 0°18' ± 05' ° |
| Camber, front | -0°13' ± 30' ° |
| Castor, front | 8°08' ± 30' ° |
| Toe-in, rear | 0°25' ± 07' ° |
| Camber, rear | -2°20' ± 30' ° |
| Camber, front | -0°30' ± 30' -0°28' ± 30' (M) ° |
| Castor, front | 8°26' ± 30' 8°28' ± 30' (M) ° |
| Toe-in, rear | 0°28' ± 07' 0°21' ± 07' (M) ° |
| Toe-in, rear | 0°29' ± 07' ° |
| Camber, rear | -2°35' ± 30' -2°50' ± 30' (M) ° |
| Camber, rear | -2°45' ± 30' ° |
| Camber, front | 0°13' ± 30' ° |
| Castor, front | 7°57' ± 30' ° |
| Toe-in, rear | 0°20' ± 07' ° |
| Camber, rear | -1°47' ± 30' ° |
Wheels and tyres
| Tyre size | 225/60R15 |
| Front tyre pressure | 2.0 bar |
| Rear tyre pressure | 2.3 bar |
Capacities
| Engine sump, incl. filter | 5.75 l |
| Manual transmission | S5D 310Z |
| Gearbox refill | 1.1 l |
| Automatic transmission | THM-R1 |
| Gearbox refill | 3.3 l |
| Differential | 1.7 (M) 1.9 (G) l |
| Cooling system | 10.5 l |
| Cooling system | 11.0 l |
| Air-conditioner refrigerant | 1550 / 1450 ± 25 g |
| Air-conditioner compressor oil | 160 - 190 / 180 - 190 ml |
Torque settings
| Cylinder head bolts — Stage 1 | 30 Nm |
| Cylinder head bolts — Stage 2 | 90 ° |
| Cylinder head bolts — Stage 3 | 90 ° |
| Front hub | 290 Nm |
| Rear hub | 260 Nm |
| Wheel nuts | 120 ± 10 Nm |
| Spark plugs | 30 Nm |
Workshop procedures for this engine
Step-by-step procedures from the workshop database.
Got a M50B20 problem? Ask for free.
Describe the symptoms — TorqFix replies with a diagnosis cited from verified workshop data.
Get free diagnosis →Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 22 Aug 2026.