OM904

The 900 series opened in 1996 with the OM 904 LA, the four-cylinder that began replacing the 300-series engines Daimler-Benz had been building for its light trucks since the 1960s. Its own engineers made the claim directly in an SAE paper that year: this small engine had features previously known only from class 8 units. Direct injection, three valves per cylinder, a twin-scroll turbocharger and air-to-air intercooling were part of it, but the significant part was high-pressure injection through solenoid-controlled unit pumps — one per cylinder, driven off a central camshaft — with injection timing, duration and quantity now decided electronically.

From 1998 it was the base engine of the Atego and it also powered the Vario, and it worked far beyond Mercedes-Benz's own vehicles: in North America Freightliner sold the family as the MBE900. Output climbed over the years from a little over 100 hp to 177 hp and 675 N·m as it was carried through Euro 3 and then the BlueTec 4 and 5 stages. Mannheim built the one-millionth 900-series engine in 2013 — by which time the third-generation Atego had already been shown with the 5.1-liter OM 934, the Euro VI successor that would end four-cylinder 900 production for trucks.