OM636

Daimler-Benz began work on it during the Second World War and had it ready by 1948, when pre-series units went into the first Boehringer-built Unimogs. The public met it in 1949 under the bonnet of the 170 D. Nothing about it was clever: a gray cast-iron block and cross-flow head, eight valves worked by pushrods, a gear-driven camshaft on the exhaust side that also turned the inline injection pump, pre-chamber combustion at 19:1, and 38 PS from 1.7 liters. Enlarged to 1.8 liters in 1954, it gave the W120 180 D 40 PS.

Volume was the achievement. The 180 D alone accounted for 116,485 cars between 1953 and 1959, most of them working for a living in the taxi ranks of Europe. Passenger-car duty ended in 1961 with the arrival of the OM621, but the engine simply moved sideways into small lorries, early Unimogs, forklifts, combine harvesters, generating sets, boats and transport refrigeration. It was license-built in Barcelona too, where SEAT fitted the 46-PS OM636.954 to its 1800 D of 1969 — and Spanish production kept going until 1990, forty-two years after the first one ran.