Mercedes-Benz M112 E28 2.8 engine

Characteristics of the M112 engine

The Stuttgart-Bad Cannstatt engine factory presents a series of engines under the M112 brand, produced from 1997 to 2005. These engines have a V-shaped configuration with six cylinders and an injection system.

The cylinder block is made of aluminum. Each cylinder has three valves and the piston stroke is 73.5 mm and the cylinder diameter is 89.9 mm. The compression ratio of the engine is 10 and its total displacement is 2,799 cubic centimeters.

The power output of the M112 engine ranges from 197 to 204 horsepower depending on the modification and rpm, while torque varies from 265 to 270 Nm at 3000 rpm.

These engines run on 95 octane fuel and meet Euro 4 environmental standards.

Average fuel consumption for the E280 W210 is 15.8 liters per 100 km in the city, 7.9 liters per 100 km on the highway and 10.8 liters per 100 km in the mixed cycle. Oil consumption can reach up to 800 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 8.0 liters. It is recommended to fill approximately 7.5 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.

M112 engine resource is more than 300 thousand kilometers in practice, and the tuning potential can reach more than 400 horsepower without loss of resource.

These engines were installed in such car models as Mercedes-Benz C 280 W202, Mercedes-Benz E 280 W210, Mercedes-Benz S 280 W220 and Mercedes-Benz SL 280 R129.

Reliability, problems and repairs of the Mercedes M112 E28 2.8L engine

Medium-volume version in the engine family M112 (which included M112 E24, M112 E26, M112 E32, M112 E32 ML AMG and M112 E37) appeared in 1997 and was positioned as a replacement for the in-line M104 E28. The new engine was based on the M112 E32 cylinder block, where the crankshaft with a shorter piston stroke was placed (84 mm was 84 mm, became 73.5 mm).

The cylinder heads are similar to those used on the M112 E32: aluminum, with one camshaft and three valves per cylinder (two for intake, one for exhaust). Inlet valves are 36mm in diameter, exhaust valves 41mm. It still uses a variable valve timing system, hydrocompensators and a variable-length intake manifold.
The timing drive is chain, the average life of the chain is about 200 thousand kilometers. The control system is Bosch Motronic ME 2.0.
The engine was intended for Mercedes models with the index 280.

The last year in the production of 2.8-liter motors was 2005, after which its place was taken by a new M272 KE30.

Modifications of M 112 E 28 engines

1. M112.920 (1997 – 2001) – version with an output of 197 hp at 5800 rpm, torque 265 Nm at 3000 rpm. It was installed on Mercedes-Benz C 280 W202.
2. M112.921 (1997 – 2002) – version with an output of 204 hp at 5700 rpm, torque 270 Nm at 3000 rpm. It was installed on Mercedes-Benz E 280 W210.
3. M112.922 (1998 – 2005) – analog of M 112.921 for Mercedes-Benz S 280 W220.
4. M112.923 (1998 – 2001) – analog of M 112.921 for Mercedes-Benz SL 280 R129.

Problems and disadvantages of Mercedes M112 2.8 liter engines

Insecure engine starting

Over the years, the M112 engine may start sluggishly or start on the 2nd or 3rd try. In most cases, this is the fault of the check valve, which is located in the submersible gasoline pump. Because of this valve, the gasoline pump does not have time to create the necessary and high enough pressure in the fuel ramp – 4 bars.

If after stopping the engine the pressure in the ramp quickly decreases to 1 bar or less, then it is necessary to deal with the check valve.

There is also a fuel pressure regulator in the submersible pump. If the supply pressure in the ramp does not reach 4 bar, it is necessary to check the regulator or the gasoline pump.

Engine stalls when the fuel gauge shows the level at half a tank

Quite a common problem on Mercedes cars is associated with the fact that the engine stalls and does not start when the fuel level reaches half. In this case, it is most likely to blame the assembly with the ejection pump, which pumps fuel from the left half of the tank to the right half of the tank, in which there is a submersible gasoline pump.

Crankshaft position sensor

The crankshaft position sensor is a known culprit of the M112 engine stalling on the run, stalling when stopped at a stoplight, not starting, or running with ignition misses in almost all cylinders. All these troubles occur on a hot engine, and when the engine cools down, it works as if nothing happened.

The culprit of these problems is the crankshaft position sensor. It simply needs to be changed. True, it is located very inconveniently – in a hard-to-reach place on the back left side of the engine.

Ignition coils

The M112 motor has 6 ignition coils, each serving 2 spark plugs (total, 12 spark plugs). Each original coil costs about $140, a good substitute is three times cheaper.
These coils in principle serve well, but they cause complaints due to oxidation of contacts to the spark plug tips, less often – due to interscrew short circuit.

If the ignition coil is defective, ignition skips appear, permanent, or at the moment of touchdown. At diagnostics it is possible to determine the inoperative cylinder. Well, to make sure that the ignition coil is inoperable, it must be swapped with any other coil.

The nominal resistance of a serviceable primary coil (between the middle and side contacts) is about 0.45 Ohm. The resistance of the secondary winding (between the high-voltage and low-voltage terminal) is 4 or 5 kOhm, depending on the ignition coil version.

You can choose and buy ignition coils for Mercedes engine in our catalog of contract parts.

Oil leaks from under the heat exchanger

It is not uncommon to see oil leaks from under the heat exchanger housing and over the oil filter cup. As a rule, oil leaks appear on the background of problems with crankcase ventilation, so do not limit yourself to replacing gaskets.

The heat exchanger itself is sealed with the oil filter cup with two ring gaskets, and the filter cup is seated on a single gasket. Their replacement is not difficult. But, again, if the leaks resume within a year, then clearly the engine has increased crankcase pressure.

Oil separators

A not-so-pleasant feature of the M112 engine is the clogging of the oil separator labyrinths located in the valve covers. Due to the accumulation of oil clots, clogging of the narrow channels of oil separators violates the outflow of crankcase gases and screening of oil vapors.

It is because of the clogging of oil separators M112 motor begins to sweat and ooze oil on the valve covers and on the seals of the oil separator.

In this case, it is necessary to remove both valve covers, remove the oil separator covers from them and thoroughly wash them, and clean them from oil clots. When reassembling the valve covers should be installed on new gaskets, and oil separator covers should be seated on the sealant and replace all the tubes of the crankcase ventilation system.
Strong oil consumption, measured by a couple of liters per 1000 km, is associated with the clogging of the drain channel in the cylinder block. This channel is located at the back of the cylinder block under the rear cover. Clogging of this channel is due to blatant economy on engine oil.

Spark plugs

The M112 engine has 2 spark plugs for each cylinder. This engine loves quality spark plugs. The original spark plugs are iridium from NGK, so it’s worth picking up this type of product from good brands. Fortunately, iridium plugs easily last 100,000 kilometers.

It is also worth inspecting the condition of high-voltage wires and check their resistance (the nominal value is indicated on them – 2.1 Kohm), because they are not eternal either and hardly survive the mileage of 150 000 km. Spark breakdown through the wires and tips causes ignition skips and loads the expensive ignition coil.

Replacement of spark plugs on the M112 engine is not so simple – the tips are pulled off with difficulty, it is better to have a suitable wrench at hand. The plugs of the 3rd and 6th cylinders are also difficult to access. Skillful masters manage to change all 12 spark plugs in 1.5-2 hours.

Fuel injectors

Fuel injectors of the M112 engine today serve well, but 10-15 years ago they quickly died because of low-quality fuel.

When clogged, these injectors negatively affect fuel consumption, so if you want to improve fuel economy, you should clean the injectors as well. Each injector is equipped with an internal filter. These filters must be removed and new ones installed. To Mercedes injectors perfectly fit mesh-filters from the remkomplekt to injectors VAZ-2110. Flushing of these injectors should be done on a special stand to see the uniformity of fuel atomization.

You can choose and buy injectors for Mercedes engine in our catalog of contract parts.

Transmission timing

Two-row timing chain M112 engine serves at least 300 000 – 400 000 km. The need to change the chain is indicated by rustling in the area of the 1st cylinder. It is better not to delay, because the stretched chain can lead to wear of timing gears, then it will be necessary to change them.

The timing chain on this engine can be changed by pulling, i.e. without much labor. But if the sprockets are worn out, the engine will have to be disassembled. Together with the timing chain it is worth replacing its hydraulic tensioner.

Cylinder piston group

The light-alloy cylinder block of the M112 engine is filled with aluminum liners with alusil coating. Questions about this material are minimal. Alusil has proved itself perfectly, the cylinder block is able to pass not less than 500 000 km. Alusil wear can occur for the same reasons as on blocks with cast iron liners, i.e. lack of oil, bad oil or overheating. Some peculiarities of liners with alusil surface – overheating can break off fragments of liners, also these liners can not be turned – the alusil layer is superficial.

Mercedes M112 2.8 engine tuning

Chip tuning. Compressor

The M112 E28 engine is almost entirely the same as its older brother M112 E32, respectively, and their tuning is monotonous. Learn about the popular and most commonly used methods here. If you install a supercharger on a 2.8 liter engine, the engine output will be ~40 hp less than the E32.

ENGINE RATING: 4+