Engine Mercedes-Benz M103 E30

Engine overview

Engine 103rd Mercedes
The new family of German units immediately received lightweight cylinder blocks (cast iron), a 12-valve cylinder head with a single camshaft and automatic valve thermal clearance regulators. The predecessor M110 used a twin-shaft 24-valve head, which was charged with increased fuel consumption, heavy weight and high production costs.

Fuel injection on M103 series engines was carried out mechanically using the KE-Jetronic type. A not very reliable single-row chain was used as a timing drive. Although it was metal, already at the 100 thousand km mark it stretched and broke off.

In 1989, the M103 engine began to be replaced by the more advanced M104 engine. Production of the 103rd was finally discontinued in 1993.

The M103 series included two units: E26 and E30. The E26 was called the little brother not only because of its smaller displacement. Even the base for it was the larger E30, released earlier. The 3-liter engine had a cylinder diameter of 88.5 mm, while the 2.6-liter engine had a 6.6 mm smaller cylinder diameter. The sizes of the intake/exhaust valves also differed. The remaining components and parts were interchangeable.

Released in 1985, the inline six-cylinder M103 E30 engine was intended to replace the M110 engine, which was outdated in all respects, and was partially unified with the four-cylinder M102 2 liter. The next M103 series (which included the 2.6-liter M103 E26) received a new lightweight cylinder block made of cast iron and a 12-valve cylinder head with one camshaft and hydraulic compensators, instead of the previous 24-valve twin-shaft, which was due to the desire to increase efficiency and reduce the weight of the power plant and the costs of its production. The diameter of the intake valves is 43 mm, the exhaust valves are 39 mm. Fuel injection system - mechanical injection.

The timing drive of the M103 motor uses a not very reliable single-row chain. The engine fuel supply system is KE-Jetronic. The successor to the three-liter M103 engine, called the M104 E30, was released in 1989, but it only managed to finally displace the M103 in 1993.

M103 E30 engine modifications

1. M103.980 (1985 - 1985) - the first version without a catalyst, power 188 hp. at 5700 rpm, torque 260 Nm at 4400 rpm. Compression ratio 10. Installed on Mercedes-Benz 300 E W124.
2. M103.981 (1985 - 1991) - analogue of M 103.980 with a compression ratio of 9.2, produced for the Mercedes-Benz 300 SE/SEL W126. Versions without a catalyst with a power of 188 hp were produced. at 5700 rpm, torque 260 Nm at 4400 rpm and with a catalyst (CAT), the power of which is 180 hp. at 5700 rpm, torque 255 Nm at 4400 rpm.
3. M103.982 (1985 - 1989) - analogue of M 103.981 for Mercedes-Benz 300 SL R107. Produced in catalytic and non-catalyst versions.
4. M103.983 (1985 - 1993) - analogue of M 103.981 for Mercedes-Benz 300 E W124/E300 W124. Produced in catalytic and non-catalytic versions.
5. M103.984 (1989 - 1993) - analogue of M103.981, power 190 hp. at 5700 rpm, torque 260 Nm at 4500 rpm. Installed on Mercedes-Benz 300 SL R129.
6. M103.985 (1985 - 1993) - an analogue of M103.983 for the all-wheel drive Mercedes-Benz 300 E 4Matic W124.

The engine was installed on the following models:

1. Mercedes-Benz 300 E W124
2. Mercedes-Benz 300 SE W126
3. Mercedes-Benz 300SL R107
4. Mercedes-Benz 300SL R129

The younger version of the M103 series, developed and released as a replacement for the ancient M123 engine, was the M103 E26. The basis for the creation of the 2.6-liter power unit was the M103 E30, the cylinder diameter of which was reduced to 82.9 mm (88.5 mm on the base engine). The cylinder head from the M103 E30 is adapted for the E26, the diameter of the intake valves is reduced from 43 mm to 40 mm, and the exhaust valves from 39 mm to 35 mm. Fuel injection system - mechanical injection.

The timing drive uses a single-row chain that is subject to tension. Fuel supply system - KE-Jetronic. Since 1992, Mercedes began producing a successor, the next version in the development of in-line six-cylinder engines, under the name M 104 E28, which in 1993 completely took the place of its predecessor.

M103 E26 engine modifications

1. M103.940 (1985 - 1992) - version for the Mercedes-Benz 260 E W124, produced in a version without a catalyst with a power of 166 hp. at 5800 rpm, torque 228 Nm at 4600 rpm and with a catalyst (CAT) 160 hp. at 5800 rpm, torque 220 Nm at 4600 rpm.
2. M103.941 (1985 - 1992) - analogue of M 103.940 for Mercedes-Benz 260 SE/SEL W126.
3. M103.942 (1986 - 1993) - analogue of M 103.940 for Mercedes-Benz 190 E W201.
4. M103.943 (1986 - 1992) - analogue of M 103.940 for Mercedes-Benz 260 E 4Matic W124.

Problems and disadvantages of Mercedes M103 engines

1. Unstable engine operation. The most common problem causing this malfunction is clogged injectors. Check, change and everything will work like clockwork.
2. Oil leaks. In the M103 engine, the crankshaft seals and the U-shaped gasket of the front cover tend to leak. In addition, the timing chain is not reliable, along with the sprockets, which tend to wear out after 100-150 thousand km. Valve seals last up to 100 thousand km, which subsequently leads to high oil consumption. In addition to all this, given the age of the engine, any other malfunctions caused by natural wear and tear may occur during operation. With quiet operation, regular maintenance and the use of high-quality working fluids, the Mercedes M103 engine will last 500-600 thousand km or more.

Series 103 engine malfunctions

Let's look at the characteristic “sores” of these units.

1. First of all, the headache of the owners of these engines was associated with oil leakage. The crankshaft seals and the front cover gasket (made in the shape of the letter “P”) did not last long.
2. After 100,000 miles, the engine lost stability. The most common reason for this was the injectors becoming clogged and requiring cleaning and, in some cases, replacement.
3. A single row timing chain is the weak link. It wore out even before the 100,000th mileage along with the sprockets.
4. The oil burn was associated with wear of the valve stem seals, which required replacement before the 100,000 mileage.

Oil for Mercedes engine

As a rule, regular maintenance, filling with high-quality lubricants and a calm driving style made it possible to operate the engine for 400-500 thousand kilometers without major repairs. However, as soon as one of the points was ignored, the problems described above began.

Modifications

Characteristics and features of motors

The Mercedes M103 3.0 engine had a full-fledged injector from the very beginning of production. This power unit was replaced by the M104 with improved design characteristics.

Mercedes M103 3.0.

The in-line six-cylinder M103 E30 engine, released in 1985, was intended to replace the M110 engine, which was outdated in all respects, and was partially unified with the four-cylinder M102 2 liter.

The next 103 series (which included the 2.6-liter M103 E26) received a new lightweight cylinder block made of cast iron and a 12-valve cylinder head with one camshaft and hydraulic compensators, instead of the previous 24-valve twin-shaft, which was caused by the desire to increase efficiency and reduce weight power plant and the costs of its production.

The diameter of the intake valves is 43 mm, exhaust valves 39 mm. Fuel injection system - mechanical injection. The timing drive uses a not very reliable single-row chain. Fuel supply system - KE-Jetronic.

Engine Mercedes M103 3.0.

M103 E26

Motor modifications

Over the long period of production of the power unit, a significant number of engine modifications were produced, which became widespread. Let's consider what varieties the M103 E30 engine has:

• M103.980 (1985 - 1985 onwards) - the first version without a catalyst, power 188 hp. at 5700 rpm, torque 260 Nm at 4400 rpm. Compression ratio 10. Installed on Mercedes-Benz 300 E W124.
• M103.981 (1985 - 1991) - analogue of M 103.980 with a compression ratio of 9.2, produced for the Mercedes-Benz 300 SE/SEL W126. Versions without a catalyst with a power of 188 hp were produced. at 5700 rpm, torque 260 Nm at 4400 rpm and with a catalyst (CAT), power of 180 hp. at 5700 rpm, torque 255 Nm at 4400 rpm.
• M103.982 (1985 - 1989) - analogue of M 103.981 for Mercedes-Benz 300 SL R107. Produced in catalytic and non-catalyst versions.
• M103.983 (1985 - 1993) - analogue of M 103.981 for Mercedes-Benz 300 E W124/E300 W124. Produced in catalytic and non-catalyst versions.
• M103.984 (1989 - 1993) - analogue of M103.981, power 190 hp. at 5700 rpm, torque 260 Nm at 4500 rpm. Installed on Mercedes-Benz 300 SL R129.
• M103.985 (1985 - 1993) - analogue of M103.983 for all-wheel drive Mercedes-Benz 300 E 4Matic W124.

Tuning options

Modifications to the M103 are rarely carried out using sports camshafts. It is very expensive, and the effect is zero. You have to use either supercharging or do a swap on the 104th. The latter initially has more power, and its components are much more technologically advanced.

Those wishing to carry out a turbo modernization should know that the ideal option would be to install the Eaton M45 compressor from M111.981. — this turbine is very productive. You should also add 300 cc injectors, a Valbro 255 pump, an intercooler and reflash the brains.

Engine M111