| Mercedes-Benz OM621 | |
| Manufacturer: | Mercedes-Benz |
| Production: | 1956–1968 |
| Predecessor: | Mercedes-Benz OM636 engine |
| Successor: | Mercedes-Benz OM615 engine |
| Configuration: | Inline-four engine |
| Bore: | NaNmm |
| Stroke: | 83.6mm |
| Block: | Cast Iron |
| Head: | Cast Iron |
| Valvetrain: | SOHC |
| Compression: | 18.0:1 |
| Fuelsystem: | Indirect injection |
| Fueltype: | Diesel |
| Coolingsystem: | Water cooled |
| Power: | NaNkW |
| Torque: | NaN0NaN0 |
The OM621 is an inline-four diesel engine produced by Mercedes-Benz, from 1956 to 1968. It was succeeded by the OM615 engine.
The OM621 is based on the petrol M121 engine, but features revised camshafts, cylinder head, pistons, and fuel injection system.[1] In 1961, the engine capacity was increased to 1988cc and power was uprated to for use in the newly introduced W110 models. After being replaced by the OM615, a 2197cc updated version of the OM621 engine was used solely in Unimog vehicles until 1988.[2]
| Engine | Displacement | Power | Torque | Years |
|---|---|---|---|---|
| OM621 I | 1897cc | at 4,000 rpm | 1080NaN0 at 2,200 rpm | 1958–1959 |
| OM621 IV | 1988cc | at 3,800 rpm | 1961–1962 | |
| OM621 III / VIII | at 4,200 rpm | 1180NaN0 at 2,400 rpm | 1961–1968 | |
| 2197cc | at 3,000 rpm | 1966–1988 |