Mercedes M104 engine

Content

Specifications M104
Modifications to the M104 engine
Problems
Mercedes M104 engine tuning

The M104 E32 is Mercedes' latest and biggest 6-cylinder engine (AMG produced the M104 E34 and M104 E36). It was first released in 1991.

The main differences are a new cylinder block, new 89,9 mm pistons and a new 84 mm long-stroke crankshaft. The cylinder head is the same as the four-valve M104 E30. The engine has a robust double-stranded structure as opposed to the single-stranded one on the old M103 engine. Since 1992, the engine has been fitted with a variable intake manifold geometry.

In general, the engine is one of the most reliable in the range, which is confirmed by many years of practical experience.

Specifications M104

The engine has the following characteristics:

manufacturer - Stuttgart-Bad Cannstatt;
years of production - 1991 - 1998;
cylinder block material - cast iron;
type of fuel - gasoline;
fuel system - injection;
number of cylinders - 6;
type of internal combustion engine - four-stroke, naturally aspirated;
power value, hp - 220 - 231;
engine oil volume, liter - 7,5.

Modifications to the M104 engine

M104.990 (1991 - 1993 onwards) - the first version with 231 hp. at 5800 rpm, torque 310 Nm at 4100 rpm. Compression ratio 10.
M104.991 (1993 - 1998 onwards) - analogue of the restyled M 104.990.
M104.992 (1992 - 1997 onwards) - analogue of M 104.991, compression ratio reduced to 9.2, power 220 hp at 5500 rpm, torque 310 Nm at 3750 rpm.
M104.994 (1993 - 1998 onwards) - analogue of M 104.990 with a different intake manifold, power 231 hp. at 5600 rpm, torque 315 Nm at 3750 rpm.
M104.995 (1995 - 1997 onwards) - power 220 HP at 5500 rpm, torque 315 Nm at 3850 rpm.

The M104 engine was installed on:

320 E / E 320 W124;
E 320 W210;
300SE W140;
S 320 W140;
SL 320 R129.

Problems

Oil leaks from gaskets;
Overheating of the engine.

If you notice that your engine has started to overheat, check the condition of the radiator and clutch. If you use high quality oil, gasoline, and do regular maintenance, the M104 will last a long time. This engine is one of the most reliable Mercedes-Benz engines.

The headache of the Mercedes M104 engine is the overheating of the rear part of the cylinder head and its deformation. You cannot avoid this because the problem is design related.

It is necessary to change the engine oil in a timely manner and use only high-quality oil. It is also required to monitor the integrity of the main cooling fan. If there is even a slight deformation of the fan blades, you must replace them immediately.