Mercedes V6 OM642 diesel engine

Power unit OM642 is the only six-cylinder passenger car engine from Mercedes, which has a V-shaped block made of aluminum. The engine considered today began to be put instead of “five” and “six” back in 2005. And what is remarkable, it is still produced. For example, the Sprinter, which has just come off the conveyor, can be purchased with internal combustion engine OM642.

Mercedes OM642 3.0 CDI engine specifications

The Mercedes OM642 3.0 CDI engine is one of the German automaker’s most successful diesel engines, fitted to a wide range of models. This engine is designed to deliver high performance with low emissions and fuel efficiency.

Main modifications:

1. OM 642 DE 30 LA red. (280 CDI/300 CDI)
2. OM 642 DE 30 LA (320 CDI/350 CDI)
3. OM 642 LS DE 30 LA (350 CDI)

Technical data:

Engine features of the OM642

The OM642 is a turbocharged V6 diesel engine with Common Rail fuel injection technology. Designed to deliver high performance while meeting strict environmental standards, it features fuel economy and high torque at low rpm.

The engine is equipped with a variable geometry turbocharger, which allows efficient control of power and torque depending on load. Common Rail fuel injection system provides precise fuel dosage, which reduces consumption and improves environmental performance.

The motor considered today, can have 184-265 horses, also vary and torque figures: 510-620 Nm.

The camber angle is 72 degrees, which is quite unusual. During casting, cast iron liners are installed. There is a two-row chain in the timing drive, which drives the balancer shaft. There are four valves per cylinder, which are driven by rockers with hydrocompensators.

The OM642 engine is equipped with a fuel system from Bosch company with a triplex plunger pump and piezoelectric injectors.

Application of the engine

The OM642 has been fitted to a wide range of Mercedes-Benz models including:

1. Sprinter (218 CDI, 318 CDI, 518 CDI)
2. ML-Class (280 CDI, 300 CDI, 320 CDI, 350 CDI)
3. E-Class (280 CDI, 300 CDI, 320 CDI)
4. GL-Class (350 CDI, 320 CDI)
5. G-Class (280 CDI, 300 CDI)
6. Viano (3.0 CDI)

This diesel engine was used in almost all cars of the company, starting from the C-Class and ending with the Gelenwagen and GL. More OM642 can be found under the hood of American cars, such as Grand Cherokee, Chrysler 300C and Commander. Also, this motor is put on copies of Sprinter, produced by Dodge and Freighliner companies.

What about the reliability of the OM642 engine?

The OM642 is known for its durability, with a life that can reach 400,000 kilometers or more with proper maintenance. It is characterized by reliability in operation, especially when using quality fuel and oil.

The main advantages of the engine are its power and high torque, making it a great choice for heavy vehicles, SUVs and commercial vehicles.

In general, the diesel engine considered today is considered to be unpretentious and German reliable. It is able to serve 500 thousand and more without any problems. But, only on condition of careful and professional maintenance, regular replacement of consumables, which there are a lot of, especially all kinds of sealing rubbers. So the motorist will not be superfluous to learn about all potential faults and vulnerabilities of this motor.

Carter ventilation valve

The power unit under consideration today has quite a classic ventilation valve – equipped with a spring-loaded diaphragm. Of course, over time, the diaphragm loses its qualities and begins to dry out. This is the reason for the deterioration of crankcase gas regulation. To understand this is quite easy: start the car, remove the oil filler plug and put the reverse side on the neck. If the internal combustion engine has problems with the circulation of crankcase gases – they will accumulate under the cap and slightly toss the plug lying on the neck. The diaphragm will need to be replaced.

Speaking of which, the gases are sucked out of the space of the right valve cover not through tubes or a special channel, but through an angled adapter resting on the camshaft. There is even a special rubber cuff between them. And again, its replacement is inevitable, because the rubber blows and lets the oil sucked into the inlet. It is not uncommon for problems to occur just because of this cuff.

Turbine O-ring

At the point of connection between the turbine and the inlet pipe (many people call it “gull”), there is a small ring, it is impossible not to notice it, because it is red. And here it will have to be changed every time you do something with the inlet pipe, because it is not characterized by durability and often leaks oil, which is in the inlet.

If you don’t replace the ring, the lubricating fluid will slowly get to the damper servo, which is right under the turbo. As time passes, the oil will corrode the actuator rod, often causing a short circuit.

Turbine

Air is supplied to the OM642 motor immediately through a pair of air ducts, where there are air filters. But the air is blown by only one turbine – Garrett GT2056V, located in the cylinder block.

The turbine is located on a small column, where the channels responsible for lubrication are made. If it is dismantled, it will expose the channels through which the lubricating fluid circulates and dirt that has been accumulating in the block for a long time will get into them. This usually happens due to the negligence of the mechanic or motorist servicing the engine. History knows a lot of breakdowns, when after dismantling and installation of the turbine mounting column, the motor broke down after a couple thousand miles from the checked liners, which suffered from frankly dirty oil.

And what number of OM642 engines went to overhaul for the completely invented reason “you haven’t changed oil for a long time”, or “just the oil pump failed” – it’s even scary to imagine.

The Garrett GT2056V is a very high quality turbo that only gives you headaches at respectable mileage. For example:

The blades wedge from accumulated soot and carbon deposits. This is manifested by strong jerks when gaining speed.
Contacts on the circuit of the actuator are destroyed, but they can be easily restored with the help of competent soldering.

But other faults in the turbine, almost always caused by malfunctions in the motor. For example, loose flaps in the manifold prevent normal air intake, and this provokes the appearance of “pompage” – pulsating pressure, which has an excessive shock load. Pompage is often the main cause of shaft failure in a turbine.

The intake manifold can also negatively affect and provoke turbine failure. The problem is in the welds, which crumble over time. And broken off pieces begin to break the rotor, hence the appearance of numerous chips. If you notice mechanical damage on the impeller in the turbocharger of the OM642 motor, it is worth replacing both intake manifolds, otherwise you will soon have to buy another turbine that is not cheap.

Vortex flaps

The intake manifold of the engine under consideration today contains the flaps. There are no problems with the flaps themselves, they are cast from quality steel. But the axles and the servo are connected by a plastic rod. Plastic becomes brittle over time, this is the reason why the plastic rods of the ears break, and this leads to play in the drive and lack of symmetry in the angles of opening of the nozzles. Favor, this is immediately noticed by the ECU due to the “responses” of the cylinders, and gives errors. Indirectly, the malfunction can be noticed by the deterioration of engine performance.

Not infrequent cases of rod breakage due to wedged shutters, the wedge of which appeared due to accumulated dirt in the inlet channels. In this case, the flaps become loose, and this negatively affects the formation of the fuel-air mixture.

Mercedes engineers suggest to eliminate this problem by replacing both parts of the intake manifold, since it is a single unit. But it is possible to find steel rods on sale without special difficulties, they, unlike plastic ones, will not break.

In principle, there is a radical solution to the problem: remove the flaps and “sew” from their ECU, but here you need a special firmware and a competent specialist.

Dirt in the intake manifold

It actively accumulates dirt, consisting of soot and oil vapors, which get into the intake through the crankcase ventilation system. So it is necessary to clean the manifold from dirt approximately every 80-100 thousand mileage. In this way, you can seriously extend the service life of the flaps.

The heat exchanger

In the collapse of the block there is a heat exchanger. In principle, it is not an outstanding oil cooler, which is responsible for the temperature of the lubricating fluid and does not allow it to warm up more than 130 degrees.

Power units OM642, made before 2010, turned out with a small flaw – the gaskets of the heat exchanger were not the best. Because of them, oil began to leak into the block. This leak is one of the reasons of pressure drop in the lubrication system, and this will certainly have a negative impact on the crankshaft liners.

At that time, the gasket was subject to warranty replacement. But if the leak appeared on a non-warranty car, then because of a penny consumable, the motorist had to go to the service station and pay for a full repair. The problem is that in order to get to the heat exchanger, you will have to almost completely disassemble the motor. But this is not all, when reassembling it will be necessary to replace a huge number of disposable rubber seals – almost 20 different rings.

The timing chain

A good and sturdy two-row chain drives the exhaust camshaft on the left and the intake camshaft on the right. The other camshafts are driven by a gear train. There are no special problems with the chain, it will start to stretch at about 300-350 thousand kilometers of mileage.

High-pressure fuel pump

The OM642 is equipped with a good pump Bosch CP3, which will serve several hundred thousand mileage without any problems. The most common malfunction is associated with the control valve of the diesel feed. If it has failed, the error P0087 will appear, indicating a drop in pressure in the ramp.

In addition, on the ramp there is a fuel pressure sensor and an adjustment valve, which is responsible for bleeding off excess pressure.

Speaking of which, not everyone knows that the Boosh CP3 fuel injector for Mercedes does not have a mechanical pump responsible for pumping. Here it is replaced by an electric analog.

Jets

Piezoelectric injectors are also supplied by Bosch and are considered very resourceful, as they can serve 300-400 thousand, but only with high-quality fuel. But on bad diesel fuel their service life is halved. In case when the engine refuses to start normally, or you notice black smoke – the wear of injectors has become critical. Their condition is easily checked by diagnostic software.

Of the significant disadvantages – injectors can not be repaired, at most you can change atomizers. But this does not always help, so you will have to look for new or used injectors. And if you see an ad for the repair of injectors, almost certainly, it is just a replacement of your parts for b\uchnye.

The main plus of piezo injectors – high speed, thanks to which they produce up to 5 injections, unlike the outdated electromagnetic, they had no more than two. This option is not only more economical, but also more environmentally friendly.

Oil pump

Quite qualitative and withstanding 300-400 thousand mileage. It gives headache only at solid mileage from 300 thousand.

Turning of liners

Extremely rare, but still occurring malfunction that leads to failure of the motor OM642. It is not always rotates all the liners, for example, the liners of the first support and the first cylinders, which do not suffer from lack of oil, can be rotated, because they are located right at the pump. And the reason why the liners rotate is still unknown. The most popular version is problems with the lubricating fluid and overheating.

And yes, the original liners are very expensive, about $40 a pair. Crank liners come in pairs, but the main liners can be bought piece by piece.