Mercedes Benz Classics: Owners Operation, Service, and Repair Workshop Manuals

Mercedes OM621 Diesel Engine Manuals

The Mercedes-Benz OM621 Diesel Engine was manufactured from 1956-1968 in three displacements of 1.9L (1,897 cc), 2.0 L (1,988 cc) and Unimog version 2.2 L (2,197 cc)

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Download: OM621 OM636 Engine Service Repair Manual

Mercedes OM621 OM636 Engine Service Repair Manual

Diesel OM621 OM636 Engine Manual
Download: 53.2mb, 723 pages, .pdf
OM621 Application: W110, W120, W121
OM636 Application: W120, W136, W191

$19.95

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Download: Unimog OM615 OM616 OM621 OM636 Engine Manual

Unimog OM615 OM616 OM621 OM636 Engine .pdf Service ManualDiesel Engines Service Repair Manual
Application: Unimog
Download: 42.8mb, 329 pages
Format: pdf document

$19.95

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OM621 Engine Technical Data

The OM621 is a inline-four diesel engine was the successor to the OM636 Diesel Engine and was succeeded itself by the OM615 engine. The OM621 is based on the petrol M121 engine variant, but features revised camshafts, cylinder head, pistons, and fuel injection system. In 1961, the engine capacity was increased to 2.0 L (1,988 cc) and power was upgraded to 40 kW (54 hp) 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.

Mercedes Benz OM621 Engine Service Repair Manual

OM621 Version Specifications

Variant Model Displacement Power Years
621.910 OM621 I 1.9 L (1,897 cc) 37 kW (50 hp) @ 4,000 rpm 1958-1959
621.913 OM621 II 2.0 L (1,988 cc) 40 kW (54 hp) @ 4,000 rpm 1961-1963
621.912 OM621 III 2.0 L (1,988 cc) 40 kW (54 hp) @ 4,200 rpm 1961-1968
621.914 OM621 IV 2.0 L (1,988 cc) 35 kW (47 hp) @ 3,800 rpm 1961-1962
Variant Model Displacement Power Years
621.915 OM621 V 2.0 L (1,988 cc) 40 kW (54 hp)  
621.916 OM621 VI 2.0 L (1,988 cc) 25 kW (33.5 hp) 1966-1967
621-918 OM621 VIII 2.0 L (1,988 cc) 40 kW (54 hp) @ 3,000 rpm 1966-1968
621.919 OM621 2.0 L (1,988 cc) 40 kW (54 hp)  
621.930 OM621 2.0 L (1,988 cc) 40 kW (54 hp)  
621.931 OM621 XI 2.0 L (1,988 cc) 29 kW (40 hp)  
621.932 OM621 2.0 L (1,988 cc) 40 kW (54 hp) 1968-1969

Version Applications

  • 621.910 = 190D, 190Db
  • 621.912 = 190DC
  • 621.913 = L319D Van/Truck, O319D Bus
  • 621.914 = 180DC
  • 621.915 =
  • 621.916 =
  • 621.918 =
  • 621.919 =
  • 621.930 =
  • 621.931 = Unimog U 40
  • 621.932 = O 309D Transporter

OM621 (37 kW version)

  • 1958–1959 W121 190D, 190Db

OM621 (35 kW version)

  • 1961–1962 W120 180Dc

OM621 (40 kW version)

  • 1961–1965 W110 190Dc
  • 1965–1968 W110 200D
  • 1966–1988 Unimog 421
Mercedes Benz OM621 Diesel Motor