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Mercedes M103 3.0L Engine Review

M103 3.0L Engine

Mercedes started produced of the M103 3.0-liter inline six-cylinder engine in 1985. It was designed for replacing the outdated M110 engine. The M103 engine has unified design with 4-cylinder M102 series. The M103 series also includes the 2.6-liter version (the M103 E26 ).

The engine has the lightweight cast iron cylinder block, aluminum cylinder head with two valves per cylinder, a single overhead camshaft, and hydraulic lifters/tappets. There is SOHC configuration of the valvetrain for reduction of the engine weight and production cost. Valves are the same as 2.0-liter M102 (intake valve diameter - 43 mm; exhaust valve diameter - 39 mm).

The engine has a mechanical fuel injection, which is very difficult to repair and adjust (KE-Jetronic). There is a single-strand timing chain also. The M103 was wholly taken off from the production in 1993 and replaced by the M104 series 3.0l engine.

Engine Specs

Manufacturer
Stuttgart-Bad Cannstatt Plant
Production years
1985-1993
Cylinder block material
Cast Iron
Cylinder head material
Aluminum
Fuel type
Gasoline
Fuel system
Fuel injection
Configuration
Inline
Number of cylinders
6
Valves per cylinder
2
Valvetrain layout
SOHC
Bore, mm
88.5
Stroke, mm
80.2
Displacement, cc
2962
Type of internal combustion engine
Four-stroke, naturally aspirated
Compression Ratio
9.2 (10)
Power, hp
180-190/5700
Torque, lb ft
188-192/4400-4500
Engine weight
Firing order
1-5-3-6-2-4
Engine oil weight
0W-30, 0W-40, 5W-30, 5W-40, 5W-50, 10W-40, 10W-50, 15W-40, 15W-50
Engine oil capacity, liter
6.5
Oil change interval, mile
6,000
Applications
Mercedes-Benz 300 E W124 (M103.980), Mercedes-Benz 300 SE W126 (M103.981), Mercedes-Benz 300 SL R107 (M103.982), Mercedes-Benz 300 SL R129 (M103.984)

M103 E30 3.0l Engine Problems and Reliability

1. Unstable engine speed. Bad injector nozzles cause this very often and the common issue.
2. Oil leaks. Oil likes to leak from crankshaft oil seals and the U-shaped front cover gasket. Also, valve stem seals are not very good and can be the reason for high oil consumption.

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