Characteristics of the M103 engine
| Parameter | Value |
|---|---|
| Manufacturing | Stuttgart-Bad Cannstatt Plant |
| Engine make | M103 |
| Years of manufacture | 1985-1993 |
| Cylinder block material | cast iron |
| Power system | injector |
| Type | row |
| Number of cylinders | 6 |
| Valves per cylinder | 2 |
| Piston stroke, mm | 80.2 |
| Cylinder diameter, mm | 88.5 |
| Compression ratio | 9.2, 10 (see modifications) |
| Engine displacement, cc | 2962 |
| Engine power, hp/rpm | 180-190/5700 (see modifications) |
| Torque, Nm/rpm | 255-260/4400-4500 (see modifications) |
| Fuel | 95 |
| Environmental regulations | – |
| Engine weight, kg | ~170 |
| Fuel consumption, l/100 km | city: 16.0, highway: 10.5, mixed: 14.5 |
| Oil consumption, gr./1000 km | to 1500 |
| Engine oil | 0W-30, 0W-40, 5W-30, 5W-40, 5W-50, 10W-40, 10W-50, 15W-40, 15W-50 |
| How much oil in the engine, liters | 6.5 |
| When replacing pour, l | ~6.0 |
| Oil change is carried out, km | 7000-10000 |
| Engine operating temperature | ~90 |
| Engine life, thousand kilometers | in practice: 400+ |
| Tuning, hp | potential: 600+ |
The factory in Stuttgart-Bad Cannstatt presents a series of engines under the brand name M103, produced from 1985 to 1993. These engines are in-line six-shaft units with cast iron cylinder block and injector feeding system.
The cylinder block is made of cast iron, each cylinder is equipped with two valves. Piston stroke is 80.2 mm and cylinder diameter is 88.5 mm. The compression ratio can vary from 9.2 to 10, depending on the modification. The M103 engine has a displacement of 2962 cubic centimeters.
Power output ranges from 180 to 190 horsepower at 5,700 rpm and torque ranges from 255 to 260 Nm in the 4,400 to 4,500 rpm range.
These engines run on 95 octane fuel and their environmental specifications are not specified. The weight of the engine is approximately 170 kilograms.
Average fuel consumption for the 300 SL R107 is 16.0 liters per 100 kilometers in the city, 10.5 liters per 100 kilometers on the highway and 14.5 liters per 100 kilometers in the mixed cycle. Oil consumption can reach up to 1500 grams per 1000 km.
Various types of oil are used to ensure engine operation, including 0W-30, 0W-40, 5W-30, 5W-40, 5W-50, 10W-40, 10W-50, 15W-40 and 15W-50, the volume of which is 6.5 liters. It is recommended to fill approximately 6.0 liters when changing the oil.
The recommended interval for oil change is 7000-10000 km. The operating temperature of the engine is approximately 90 degrees Celsius.
M103 engine resource is more than 400 thousand kilometers in practice, and the tuning potential can reach more than 600 horsepower without loss of resource.
These engines were installed in such car models as Mercedes-Benz 300 E W124, Mercedes-Benz 300 SE W126, Mercedes-Benz 300 SL R107 and Mercedes-Benz 300 SL R129.
Reliability, problems and repairs of the Mercedes M103 engine
Introduced in 1985, the M103 E30 inline six-cylinder engine was designed to replace the M110 motor, which was obsolete in all respects, and was partially standardized with the 2-liter four-cylinder M102. The new M103 series (including the 2.6-liter M103 E26) received an improved cast iron cylinder block and a single camshaft head with hydrocompensators, instead of the previous 24-valve twin-shaft design, to improve fuel economy, reduce powerplant weight and reduce production costs. The intake valves were 43 mm in diameter and the exhaust valves were 39 mm in diameter. A mechanical injection system was used for fuel supply.
The timing system used a single-row chain, which was not always very reliable. The fuel supply system was called KE-Jetronic.
The successor of the three-liter engine M103 was M104 E30, which was released in 1989, but it managed to completely displace M103 only by 1993.
Modifications of M 103 E 30 engines
- M103.980 (1985 – 1985 vintage) – the first version without catalyst, power 188 hp at 5700 rpm, torque 260 Nm at 4400 rpm. Compression ratio 10. It was installed on Mercedes-Benz 300 E W124.
- M103.981 (1985 – 1991) – analog of M 103.980 with a compression ratio of 9.2., produced for Mercedes-Benz 300 SE/SEL W126. There were produced versions without catalytic converter with an output of 188 hp at 5700 rpm, torque 260 Nm at 4400 rpm and with catalytic converter (CAT), with an output of 180 hp at 5700 rpm, torque 255 Nm at 4400 rpm.
- M103.982 (1985 – 1989) – Analogous to the M 103.981 for the Mercedes-Benz 300 SL R107. Produced in catalyst and catalyst-free versions.
- M103.983 (1985 – 1993) – analog of M 103.981 for Mercedes-Benz 300 E W124/E300 W124. It was produced in catalyst and catalyst-free versions.
- M103.984 (1989 – 1993) – analog of M103.981, power 190 hp at 5700 rpm, torque 260 Nm at 4500 rpm. It was installed in Mercedes-Benz 300 SL R129.
- M103.985 (1985 – 1993) – analog of M103.983 for all-wheel drive Mercedes-Benz 300 E 4Matic W124.
Problems and disadvantages of Mercedes M103 engines
Instable engine performance
The most popular problem causing this malfunction is clogged injectors. Check, change and everything will work like clockwork.
Oil Leaks
In the M103 engine likes to leak crankshaft oil seals and U-shaped gasket of the front cover.
In addition, the timing chain, along with the sprockets, which tend to wear out by 100-150 thousand kilometers, is not reliable. Oil caps live up to 100 thousand kilometers, which subsequently leads to high oil consumption. In addition to all this, given the age of the engine, in the process of operation may occur and any other faults caused by natural wear. With quiet operation, regular maintenance and the use of quality working fluids, the engine Mercedes M103 is 500-600 and more thousand kilometers.
Mercedes M103 engine tuning
Compressor
The situation with the refinement of the M103 engine is similar to the four-cylinder M102: attempts to make a sporty atmospheric will cost a lot of money, and will not bring significant results, therefore you need to either inflate, or buy a Mercedes M104 engine, which has initially greater power, or a more modern Mercedes. This step will be the ideal choice in the price/quality ratio.
For supercharger enthusiasts, just install an Eaton M45 compressor from the M111.981 with intercooler (or better), ~300 cc injectors, Walbro 255 pump, tune to Megasquirt and drive until it falls apart. Further to collect on forged piston with compression ratio ~8 and blow in full.
An alternative option is to buy a full turbo kit, such kits provide 500++ hp, the price of solutions is 1.5-2 times higher than the cost of the car itself.
MOTOR RATING: 4