On another forum, it was asserted that the 300 engine was derived from a fire truck engine produced pre-war. I had never heard this, but in searching the web I found a piece on eMercedes.com about the 300 SL:
"A promising engine for further development was the robust M 159, as it was called internally – a 2.6 liter six-cylinder unit that had been developed in the late thirties for the new 260 model but did not make it to large-scale production because of the outbreak of World War II. Nevertheless, the engine did not remain at the testing stage – it proved itself many times over in light trucks and fire-fighting vehicles. This engine became the basis for a new series. Its – originally progressive – concept incorporated overhead valves suspended in the cylinder head in V-shape and operated from a camshaft below, as well as a spark plug located in the pent-roof shape combustion chamber between the valves. The engine was designed for a high level of fuel economy and an output of between 60 and 70 hp.
After World War II, the M 159 was taken through several evolutionary stages. It eventually entered large-scale production in the form of the M 186, with an oblique contact surface between cylinder head and engine block, overhead camshaft, large intake valves, combustion space in piston and engine block, a displacement of three liters and an output of 115 hp"
This engine was in the L 1500 truck. Oswald says this engine was an overhead valve, Lewandowski says side valve. It seems a stretch to say that it was the basis for the 300, since it wasn't an OHC, and the valve arrangement in a V wasn't the layout of the 300 valves. Was it in fact a major development from the typical MB engines pre-war?
Comments from the experts on trucks?? Does anyone have pictures or drawings of this engine?