Mercedes-Benz OM621 engine

The OM621 is an inline-four diesel engine produced by Mercedes-Benz, from 1956 to 1968. It was succeeded by the OM615 engine.

Mercedes-Benz OM621
Overview
ManufacturerMercedes-Benz
Production1956–1968
Layout
ConfigurationInline-four engine
Displacement
  • 1.9 L (1,897 cc)
  • 2.0 L (1,988 cc)
  • 2.2 L (2,197 cc)
Cylinder bore85–87 mm (3.35–3.43 in)
Piston stroke83.6 mm (3.29 in)
Cylinder block materialCast Iron
Cylinder head materialCast Iron
ValvetrainSOHC
Compression ratio18.0:1
Combustion
Fuel systemIndirect injection
Fuel typeDiesel
Cooling systemWater cooled
Output
Power output35–40 kW (47–54 hp)
Torque output108–118 N⋅m (80–87 lb⋅ft)
Chronology
PredecessorMercedes-Benz OM636 engine
SuccessorMercedes-Benz OM615 engine

Design

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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 2.0 L (1,988 cc) and power was uprated to 55 PS (40 kW) for use in the newly introduced W110 models. After being replaced by the OM615, a 2.2 L (2,197 cc) updated version of the OM621 engine was used solely in Unimog vehicles until 1988.[2]

Models

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Engine Displacement Power Torque Years
OM621 I 1.9 L (1,897 cc) 37 kW (50 PS)
at 4,000 rpm
108 N⋅m (80 lb⋅ft)
at 2,200 rpm
1958–1959
OM621 IV 2.0 L (1,988 cc) 35 kW (48 PS)
at 3,800 rpm
1961–1962
OM621 III / VIII 40 kW (55 PS)
at 4,200 rpm
118 N⋅m (87 lb⋅ft)
at 2,400 rpm
1961–1968
2.2 L (2,197 cc) 40 kW (55 PS)
at 3,000 rpm
1966–1988

OM621 (37 kW version)

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OM621 (35 kW version)

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OM621 (40 kW version)

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References

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  1. ^ Long, Brian (2014-01-31). Mercedes-Benz 'Fintail' Models: The W110, W111 and W112 Series. Crowood. ISBN 9781847976048.
  2. ^ "1964-1993". www.mercedes-benz.co.uk. Retrieved 2018-07-22.