Mercedes M108 Petrol Engine Manuals

Mercedes Benz M108 2.5 liter 2496 cc single overhead camshaft (SOC) inline six-cylinder petrol engine used two Zenith 35/40 INAT carburetors, and was produced 1965 to 1969.

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Download: Mercedes Benz M108 Engine Service Manual

Mercedes M108 Engine Repair Manual
Application: W108 250S
Download: 86.9mb, 911 pages
Format: .pdf document

USD $19.95

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See Multi Unit Engine Manual Applications M108, M127, M129, M189

Download: Mercedes Benz M108 Engine Parts Manual

M108 Engine Exploded Parts Picture Catalog
Download: 1.27mb, 13 pages
Format:,.pdf document

USD $9.95

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M108 Engine Technical Data

The Mercedes-Benz M108 is a six-cylinder gasoline engine that was produced from 1965 to 1969 and was only used in the Mercedes-Benz W108 250S model.

This M108 engine is a version of the Mercedes-Benz M180 engine, but featured a larger displacement of 2496 cc, with a cylinder bore of 82mm and stroke of 78.8mm. Compression ratio was 9: 1 with a power output of 110 hp at 5.000 rpm to 130 hp at 5.400 rpm, and a maximum torque of 194 Nm at 4000 rpm. It featured a 6-cylinders inline cast iron engine block with seven crankshaft main bearings, a cylinder head made of aluminum alloy, and a single overhead camshaft with two valves per cylinder. Fuel was served by two Zenith 35/40 INAT carburetors.

M108 Engine Faults

This engine and the simultaneously built injection engine M129 were criticized for being susceptible to an accumulation of engine damage due to thermal problems. Issues evolved from three pairs of cylinders having unequal spacing and a longer stroke. At the end of the higher piston stroke, and at high speeds, these engines would get thermally overwhelmed causing damage. Strong load before reaching the operating temperature could also cause engine damage (piston seizure). These type M108 and M129 motors were therefore only produced for a very short period of time.

Mercedes M108 Application
Series	Model	Years	Engine	Production	hp
W108	250S	1965-1969	108.920	1965-1969	130

The M108's successor engine type M130 eliminated this issue with uniform cylinder spacing which offered better cooling. In turn, the short production runs of the M108 and M129 make these motors the rarest Mercedes engines. This rarity means original M108 and M129 engines which were installed in series W108, W111 and W113 model vehicles will pose more of a challenge in locating engine parts making them harder to repair.

Engines Covered in this Multi Unit Manual

While this multi unit manual covers all engines listed here, it is recommended that the linked manuals below be used for those specific motors