The Mercedes Benz M180 Engine was a

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 ...

cylinder

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

introduced 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 to power the company's new 220 (W187). It was the first engine with a cylinder bore greater than its stroke that Mercedes had installed in a production car, while using a

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 ...

. It spawned four variants through 1968, the final and largest being the 2.8 L M130. It was achieved by boring out and stroking the M180's original "over-square" bore × stroke of to , yielding a displacement of . Mercedes also unveiled at the 1951 Frankfurt Motor show a larger 3.0-litre M186 ‘big six’ inline-6 to power its new flagship 300 (W186) ''Adenauer'' four-door saloon. While sharing many design features such as staggered valve arrangement and rockers running off a single overhead camshaft driven by a duplex cam-chain, the engines were of completely different design with little or no inter-changeability of parts.''Six Appeal'', Mercedes Enthusiast, May 2007, pp 52-58

M180 Variants

M180

The original M180 engine was rated at . It powered the W187 220 sedan,

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 ...

, and

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 ...

(Type A and B) from 1951 to 1955, the W180 220a sedan, coupé, and cabriolet from 1954 to 1956 and the W105 219 4-door sedan from 1956 to 1959. It also powered the

Unimog 404 The Unimog 404, also called the Unimog S and Unimog 404 S, is a vehicle of the Unimog-series by Mercedes-Benz, produced in the Unimog plant in Gaggenau from 1955 to 1980. Marketed as ''Unimog U82'', and later ''Unimog U110'', 64,242 units of the ...

, a military version of the

Unimog The Unimog (, ) is a range of multi-purpose tractors, trucks and lorries that has been produced by Boehringer from 1948 until 1951, and by Daimler Truck (formerly Daimler-Benz, DaimlerChrysler and Daimler AG) since 1951. In the United States and ...

, which was built from 1955 until 1980.

M127

The W180 Ponton 220S Sedan, Coupe and Cabriolet of 1956-1959 benefited from the up-rated M180.924 which delivered . In 1958 Bosch

mechanical fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All comp ...

was added to the 2.2-litre six and the engine, now giving , was redesignated M127. The M127 was fitted to the last of the Pontons: the rare 1958 W128 220SE, of which fewer than 4000 were produced. In 1959 the first series of

W111 : ''See Mercedes-Benz S-Class for a complete overview of all S-Class models.'' The Mercedes-Benz W111 was a chassis code given to a range of Mercedes-Benz vehicles produced between 1959 and 1971, including four-door saloons (1959-1968) and two- ...

"Fintail" 220SE and 220SEb models was introduced, with the carburetted M180 in the 220b and 220Sb and the M127 used in the 220SEb. The addition of the lower case ‘b’ was added to differentiate the Fintails from the earlier Pontons. In 1965 the W111/W112 sedans were superseded by the new W108/109 series 250 and 250S (apart from the

230/230S, produced from 1965 to 1968). The M180 was bored by , creating an bore × stroke of and displacement of . All models received the new 2.3 L engine.

M129

The M180's stroke was increased to produce the 2.5 L engine for the new

Mercedes-Benz W108 The Mercedes-Benz W108 and W109 are luxury cars produced by Mercedes-Benz from 1965 through to 1972 (or 1973 in North America). The line was an upgrade of the Mercedes-Benz W114/W115, to succeed the W111 and W112 ''fintail'' sedans. The cars w ...

250S and 250SE. A increase resulted in a bore × stroke of and displacement of , carburetted on the 250S and fuel-injected on the 250SE, designated the M129. The M129 was fitted with a mechanically controlled six-piston fuel injection pump. A change from four to seven main bearings was necessary in order smoothly to handle the resulting increase in power. A larger capacity oil pump was also specified.

Connecting rod A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the cranksh ...

s were slightly shortened, reflecting the longer stroke in a block of unchanged overall height. The redesigned

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...

s incorporated larger ports, and the valve diameters were increased by . On the fuel injected cars a six-plunger pump replaced the previous car's two plunger pump and the injectors were repositioned to give a more direct angle towards the inlet valve heads. The engine cooling fan now had six blades instead of four and incorporated a viscous coupling which activated the fan only when engine speed exceeded 3,000 rpm or the radiator water temperature reached a preset limit. The engine of the 250 S was called M108 (for W108 chassis) and only the 250 SE engine was designated M129.

M114

In 1968 the ‘New Generation’ or /8 models were introduced, along with a change to the venerable mid-size six. The M180 engine of the 230/230S was continued in the W114 230 and 230.6, while the M180 of the 250S underwent a few changes and was renamed the M114. This was also available with Bosch D-Jetronic fuel injection, as fitted to the 250CE.

M130

In 1968 the 2.5L M129 of the 250SE was superseded by the 2.8L M130, the ultimate variant of the mid-sized six, obtained by increasing the bore by . The result was a bore × stroke of ; ), the maximum practical enlargement of the engine given the limitations of the block, which required deletion of water passages between the cylinders. It was used in the W108 280S and 280SE, in the W109 300SEL from December 1967 to January 1970, and in the W113 280SL.

M123

The final incarnation of the M180 line of engines was the 2.5L M123, fitted with the notorious

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 ...

four-barrel carburator in the W123 chassis 250 produced between 1975 and 1985.

References

{{DEFAULTSORT:Mercedes-Benz M180 Engine M180 Straight-six engines Gasoline engines by model