The first car with an M20 engine was the BMW E12 520/6, which was fitted with a 2-liter M20B20 modification. The cylinder diameter is 80 mm, the piston stroke is 66 mm. The M20B20 engine was first equipped with a Bosch L-Jetronic injector in 1982 on a BMW 520i. In 1987 it was updated using a Bosch Motronic catalytic converter system.
Specifications
| Manufacturer | Munich Plant |
| Family | M20 |
| Production years | 1977-1992 |
| Cylinder block alloy | cast iron |
| Fuel system | carburetor/injector |
| Configuration | inline |
| Number of cylinders | 6 |
| Valves per cylinder | 2 |
| Piston stroke, mm | 66 |
| Cylinder bore, mm | 80 |
| Compression ratio | 9.2 9.8 9.9 9.8 8.8 |
| Displacement, cc | 1991 |
| Power output, hp | 122/6000 125/5800 126/5800 129/6000 129/6000 |
| Torque output, Nm / rpm | 160/4000 170/4000 170/4000 174/4000 174/4300 |
| Fuel type | petrol |
| Weight, kg | ~113 (dry) |
| Fuel consumption, L/100 km (for E30 320i) — city — highway — combined |
13.0 7.5 9.5 |
| Oil consumption, gr/1000 km | up to 1000 |
| Recommended engine oil | 5W-30 / 5W-40 / 10W-30 / 10W-40 / 10W-50 / 15W-50 |
| Engine oil capacity, liter | 4.25 |
| Normal engine operating temperature, °C | ~90 |
| Engine lifespan, km | ~300 000 |
Frequent problems
When using M20B20 engines, they face wear on the camshaft, overheating, and violation of the integrity of the cylinder head.
The cylinder head can move when overheated. To avoid cylinder head failure, at the first sign of overheating, you need to check the health of the cooling system. The system is checked for air pockets, which are removed by blowing. It is also necessary to assess the condition of the thermostat, pump and radiator.
Cylinder head may crack due to engine overheating. Often a crack occurs in the area of the 4-5 cylinder; the problem can be eliminated by replacing the part.
The condition of the timing belt and the location of the tensioner roller should be carefully monitored in order to avoid belt breakage, valve bending, piston breakage.
For motors with a range of 200 thousand kilometers or more, camshaft wear is characteristic, which is determined by a knock. To solve the problem, a new cylinder head is installed.
