Engine Mercedes OM621

The 2.0 liter OM621 engine belongs to the second generation of lightweight diesel engines. Introduced in 1956 and later replaced by a new engine family in 1968. It is based on the M121 gasoline engine but has redesigned camshafts, cylinder head, pistons and fuel injection system.

It is a lower shaft, prechamber, with a gear drive. The camshaft and injection pump are driven by a 2-row chain with a hydraulic tensioner. It should be noted that the chain drive is used on all Mercedes engines, without exception, because reliability is paramount for them. This engine is not very powerful, but it demonstrates solid torque at low revs. Without turbocharging.

Specifications

Engine’s type diesel
Tradename OM 621
Power, hp / kW 50 / 37
Displacement, cc 1990
Number of cylinders 4
Number of valves 8
Compression ratio 21:1
Cylinder bore, mm 87
Piston stroke, mm 83
Crankshaft bearings 5
Configuration inline
Fuel type diesel fuel
Turbine suction pump
Cylinder head SOHC/OHC
Timing mechanism chain
Timing rocker arm
Cooling water

Generations of OM621 engines

Also called Displacement Power Torque output Production years
OM621 I 1.9 l. (1897 cc) 37 kW (50 hp)
@ 4000 rpm
108 Nm
@ 2200 rpm
1958–1959
OM621 IV 2.0 l. (1988 cc) 35 kW (47 hp)
@ 3800 rpm
1961–1962
OM621 III / VIII 40 kW (54 hp)
@ 4200 rpm
118 Nm
@ 2400 rpm
1961–1968
2.2 l. (2197 cc) 40 kW (54 hp)
@ 3000 rpm
1966–1988

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