Mercedes-Benz M123 engine

The Mercedes-Benz M123 is a family of 2.5 litre (2,525 cc) straight-six overhead camshaft petrol engines developed for the new W123 range and used from 1976 to 1984 in the 250 and 250 T models. Naturally aspirated and fed by a four-barrel Solex carburettor, it replaced the M180 in the 230 and the 2.8 litre M130 in the 250 derived from the W114 series. Like the M180 it has only four crankshaft bearings, but its cylinders are evenly spaced, as in the M130, and it has a chain-driven single overhead camshaft working vertical valves through rocker levers. Quiet but thirsty, it was the only engine newly developed for the 123 series, was uprated in 1979, and was succeeded by the M103 in 1984.