Mercedes Benz Classics: Owners Operation, Service, and Repair Workshop Manuals

Mercedes M186 Petrol Engine Manuals

The Mercedes-Benz M186 3.0 liter 2,996 cc petrol engine came in two versions that produced 115 and 125 hp being fitted with twin downdraft Solex carburetors, 1951 to 1967

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Download: Mercedes M186 Engine Service Manual

Mercedes M186 M188 M199 Multi Engine Service Repair ManualMercedes M186 Engine Repair Manual
Download: 36.2mb, 204 pages, .pdf
Variations: M186, M188, M199
Application: W186, W188

USD $19.95

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Multi Unit Engine Manual Applications M186 M188 M199

Download: Mercedes M186 Engine Parts Manual

Mercedes M186 Engine Parts ManualMercedes M186 Engine Parts Manual
Variations: M186
Application: W186, W188
Download: 9.67mb, 67 pages, .pdf

USD $9.95

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Download: Mercedes Benz M186 300b 300c Carburetor Manual

Mercedes M186 Solex Type 32 PAIAT Carburetor ManualMercedes M186 Solex Type 32 PAIAT
Carburetor Service Manual
Application: W186 300b 300c
Download: 6.78mb, 31 pages, .pdf

USD $12.95

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Download: Mercedes Benz M186 300 Carburetor Manual

Mercedes M186 Solex Type 40 PBIC Downdraft Carburetor ManualMercedes M186 Solex Type 40 PBIC Downdraft
Carburetor Service Manual
Application: W186 300, W188 300S
Download: 3.86mb, 19 pages, .pdf

USD $9.95

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M186 Engine Technical Data

The M186 Engine inline-6 cylinder 3.0 liter 182.8 cu in. single overhead camshaft engine was developed in the early 1950s to power the company's new flagship, the (W186) 300 "Adenauer" four-door saloon. It made its debut at the Frankfurt Motor Show in April of 1951. It featured an iron block, aluminum head engine with deep water jackets designed to give reliable service under prolonged hard use. An innovative diagonal head-to-block joint allowed for oversized valves enhancing engine performance along with thermostatically controlled oil cooling, copper-lead bearings, and a hardened crankshaft.

The M186 shared many design features with the Mercedes' 2.2 L (134 cu in) M180 engine featuring a staggered valve arrangement and rockers running off a single overhead camshaft driven by a duplex cam-chain. The term "big six" is often used to distinguish the large block M186 3.0 L from the small block M180 and its derivatives.

The M186 featured a slightly under-square bore and stroke of 85 mm × 88 mm (3.35 in × 3.46 in), allowing it to produce 115 bhp (117 PS; 86 kW) at a 6.4:1 compression ratio.

Mercedes Benz M186 Motor

M186 Variants, Versions and Applications

Variants of the M186 went on to be used in the exclusive M188 300 S/300 Sc gran tourer, the iconic W198 Gullwing 300SL sports car, Mercedes top-end 300-series sedans and limousines and coupes of the early to mid-1960s. Variants of the M186 (M189 – M199) saw compression ratios rise and the number of carburetors multiplied or replaced with fuel-injection, providing higher performance. Production ended in 1967.

M186 Engine Variants

  • The M188 variant was fed by triple downdraft Solex carburetors and producing 150 hp (112 kW) at 5000 rpm and 7.8:1 compression ratio.
  • The M189 used a Bosch indirect fuel injection system to up performance from the underpowered M186 to 178 hp at 5500 rpm and later 170 hp.
  • The M194 was used in the W194 300SL racer outfitted with three two-barrel Solex carburetors. 10 were made, 3 produced 228 hp, 7 @ 241 hp.
  • The M198 added a sand-cast aluminum intake manifold and fuel-injection for the 300SL "Gullwing" producing 212 hp at 5,800 rpm, 203 lb.ft of torque at 4,600 rpm.
  • The M199 was a significantly detuned direct-injection dry sump oil system engine used in the W188 300 Sc producing 175 hp at 5400 rpm and 8.55:1 compression.

M186 SOHC inline-6 versions

Version Disp. Bore & Stroke Comp. Power Torque
186.920 2996 cc 85 x 88 mm 6.4 (86 kW 115 hp) at 4600 rpm 145 lb.ft at 2500 rpm
186.921 2996 cc 85 x 88 mm 7.4 (93 kW 125 hp) at 4500 rpm 163 lb.ft at 2600 rpm

Applications

    Mercedes M186 Big-Six
  • 1952-1954 Mercedes-Benz 300 Sedan
  • 1952-1954 Mercedes-Benz 300 Sedan
  • 1952-1954 Mercedes-Benz 300 Cabriolet
  • 1955 Mercedes-Benz 300 b Cabriolet
  • 1955 Mercedes-Benz 300 b Sedan
  • 1955 Mercedes-Benz 300 b Sedan
  • 1956-1957 Mercedes-Benz 300 c LWB
  • 1956-1957 Mercedes-Benz 300 c Sedan
  • 1956-1957 Mercedes-Benz 300 c Sedan
  • 1956-1957 Mercedes-Benz 300 c LWB
  • 1956-1957 Mercedes-Benz 300 c LWB
  • 1956-1957 Mercedes-Benz 300 c Sedan
  • 1956 Mercedes-Benz 300 c Cabriolet
  • 1956 Mercedes-Benz 300 c Cabriolet
  • 1956-1957 Mercedes-Benz 300 c LWB
  • 1956-1957 Mercedes-Benz 300 c Sedan

The M186 engine that powered the 300 series was the engine from which the 3-liter (2996 cc) 300SL Gullwing M198 engine was developed being very much a "state of the art" design in April of 1951.

Mercedes M186 Engine

Engines Covered in this Multi Unit Manual

Mercedes Benz M186 6 Cylinder Engine