Mercedes-Benz M186 engine

The Mercedes-Benz M186 was a 3.0 litre single overhead camshaft inline-six, the so-called big six, developed in the early 1950s to power the new flagship 300 Adenauer (W186) four-door saloon. It made its debut at the Frankfurt Motor Show in April 1951. The iron block and aluminium head had deep water jackets, a diagonal head-to-block joint that allowed oversized valves, a reverse-flow head, thermostatically controlled oil cooling, copper-lead bearings and a hardened crankshaft. With twin downdraft Solex carburettors it made 115 bhp at a 6.4 to 1 compression ratio. Its derivatives, the M188 to M199, powered the 300 S, the W194 racer, the 300 SL gullwing and roadster and the 300 SE, until production ended in 1967. It shares design ideas with the smaller M180 but almost no parts.