The Mercedes Benz M186 Engine was a 3.0–litre

single overhead camshaft An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...

inline-6 The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine balan ...

developed in the early 1950s to power the company's new flagship 300 "Adenauer" (W186) four-door saloon. It made its debut at the

Frankfurt Motor Show The International Motor Show Germany or International Mobility Show Germany, in German known as the ''Internationale Automobil-Ausstellung'' (''IAA'' – International Automobile Exhibition), is one of the world's largest mobility shows. It cons ...

in April 1951. Designed to give reliable service under prolonged hard use, the iron block/aluminum head engine featured deep water jackets, an innovative diagonal head-to-block joint that allowed for oversized intake and exhaust valves,

reverse-flow cylinder head In engine technology, a reverse-flow or non-crossflow cylinder head is one that locates the intake and exhaust ports on the same side of the engine. The gases can be thought to enter the cylinder head and then change direction to exit the head. T ...

, thermostatically controlled oil cooling, copper-lead bearings, and a hardened crankshaft. Variants of the M186 went on to be used in the exclusive 300 S/300 Sc gran tourer, iconic gullwing 300SL sports car, and Mercedes top-end 300-series sedans and limousines, and coupes of the early to mid-1960s. Production ended in 1967, four years after the introduction of the

600 __NOTOC__ 600 ( DC) was a leap year starting on Friday (link will display the full calendar) of the Julian calendar. The denomination 600 for this year has been used since the early medieval period, when the Anno Domini calendar era became the ...

''Grosser Mercedes'' and the M100 V-8. The various versions of the engine (M186 – M199) produced from as compression ratios rose and the number of carburettors multiplied or were replaced with fuel-injection. While sharing many design features with Mercedes' M180 engine introduced at the same show (such as staggered valve arrangement and rockers running off a single overhead camshaft driven by a duplex cam-chain), the two were of completely different design with little or no inter-changeability of parts. The term "big six" is sometimes used to distinguish the large block 3.0 L M186 from the small block M180 and its derivatives.

M186 Variants

M186

The 3.0–litre () M186 was introduced in 1951 for use in the company's flagship 300 "Adenauer" (W186) four-door saloon. It had a slightly under-square bore and stroke of , featured an

overhead cam An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...

, and an aluminum head with an innovative 30-degree diagonal head-to-block joint that allowed for oversized intake and exhaust valves. Designed to give reliable service under prolonged hard use, the engine featured deep water jackets, thermostatically controlled oil cooling, copper-lead bearings, and a hardened crankshaft. Fitted with twin downdraft

Solex Solex may refer to: * Solex (musician), Dutch musician * Solex Carburetor, a French manufacturer of carburetors and the powered bicycle VéloSoleX * Solex College, a former private for-profit college in Chicago, Illinois * Solex Unit, a fictiona ...

carburettors it produced at a 6.4:1 compression ratio.

M188

The W188 300 S

coupé A coupe or coupé (, ) is a passenger car with a sloping or truncated rear roofline and two doors. The term ''coupé'' was first applied to horse-drawn carriages for two passengers without rear-facing seats. It comes from the French past parti ...

cabriolet A convertible or cabriolet () is a passenger car that can be driven with or without a roof in place. The methods of retracting and storing the roof vary among eras and manufacturers. A convertible car's design allows an open-air driving expe ...

was released in 1952 with the M188 variant, being fed by triple downdraft

carburettors and producing at 5000 rpm and 7.8:1 compression ratio.

M189

The first M189 appeared in the 300d pillarless limousine of 1957, three years after the M198. It used Bosch indirect fuel injection to up performance from the underpowered M186 to at 5500 rpm. The engine then appeared in 1961 in the

Mercedes-Benz W112 : ''See Mercedes-Benz S-Class for a complete overview of all S-Class models.'' The Mercedes-Benz W112 is a luxury automobile produced by Mercedes-Benz from 1961 to 1967. Marketed as the 300SE, it was available as a coupé, convertible, sedan, ...

300SE and its long wheelbase derivative (also called 300SE; the SEL nomenclature would first be used on the subsequent W109 LWB sedans) two years later. From 1964, power output was . The final incarnation of the M189 was in the W108 300SEb and W109 300SEL of 1965–1967, producing .

M198

The high-performance M198 was created in 1954 for the first generation of the 300SL, known colloquially as the "Gullwing". To fit under its low profile hood the engine was tilted 50-degrees to the left. The result for the car was aerodynamic efficiency, and an enormous sand-cast aluminum intake manifold that stretched across the engine's entire breadth.1957-’63 Mercedes-Benz 300 SL Roadster, hemmings.com
/ref> In order to deliver track-ready performance, race-derived features were built in, including a

dry sump A dry-sump system is a method to manage the lubricating motor oil in four-stroke and large two-stroke piston driven internal combustion engines. The dry-sump system uses two or more oil pumps and a separate oil reservoir, as opposed to a conve ...

lubrication system and Bosch mechanical direct fuel-injection, one of the first production cars with fuel injection. This engine produced DIN

net Net or net may refer to: Mathematics and physics * Net (mathematics), a filter-like topological generalization of a sequence * Net, a linear system of divisors of dimension 2 * Net (polyhedron), an arrangement of polygons that can be folded up ...

at 5,800 rpm and DIN net of torque at 4,600 rpm and net (brake hp) at 6,100 RPM and net torque at 4,800 RPM. An optional high-performance "Sport" camshaft was also available. This was the only available configuration for the Roadster version of the 300 SL when it made its debut in 1957. Production ended in 1964.

M199

A significantly detuned direct-injection, dry sump oil system engine was used in the late W188 300 Sc of 1955 to 1958 producing at 5400 rpm and 8.55:1 compression ratio

References

{{DEFAULTSORT:Mercedes-Benz M186 Engine M186 Straight-six engines Gasoline engines by model Slant engines