At the request of customers, Mercedes-Benz also produced a 3.0-liter 6-cylinder E 300 D diesel engine, designated on the domestic market as OM 606. This model has tangible advantages due to the reduction of noise and vibration. Thus, the noise from the engine in the passenger compartment of the E 300 D is even lower than that of a model with a gasoline inline 6-cylinder engine.
Technically, the diesel E 300 D corresponds to the 4-cylinder diesel engine E 220 D (OM 604) with a volume of 2.2 liters, but to a greater extent - a 5-cylinder diesel engine E 250 D (OM 605): 4-valve cylinder head with prechamber, electronically controlled, CAN-connected in-line injection pump, 2-mass flywheel on models with manual transmission. The crankshaft of a 6-cylinder engine has seven main bearings. A distinctive feature of the E 300 D diesel engine is an adjustable air supply system, which is a three-stage resonant tube with movable dampers and a length that changes depending on the speed. The suction length is maximum at low RPM, when optimal boost is required, and decreases as power increases.
As with the E 220 D and E 250 D diesels, as with the E 300 D, the catalytic analyzer ensures an environmentally acceptable exhaust gas emission. The emission of harmful substances in 4-valve diesel models is less by one third compared to 2-valve ones, which allows to reduce the toxicity of exhaust gases by 20%.