Moreover, unlike the prechamber engine, the direct-injection engine made do without starting aids – at least as long as the temperatures did not fall below minus 15 degrees Celsius. Only then did the driver fall back on the so-called Start Pilot, that standard device in those days that introduced a hydrocarbon compound to the intake manifold, causing the engine to start immediately. Finally, the third major advantage of the direct-injection engine is that it generates much less soot than the prechamber engine owing to more efficient combustion.
Though the engine weight and the bore and stroke, as well as the output, of the OM 346 and OM 352 were identical with the predecessors' statistics, the details of the technology proved to be completely different: precombustion chambers and glow plugs were eliminated, the combustion chamber was now in the piston, and the intake ducts were redesigned.
The injection nozzle of the OM 352: angled and slightly off-centre.