Engine Mercedes OM642

Engine Mercedes OM642

The OM642 engines are a family of 6-cylinder V-shaped diesel engines with direct injection and a turbocharger from Mercedes-Benz, produced since March 2005. The working volume of the OM642 diesel engine is 3 liters, the camber angle of the block is 72 degrees (which is completely atypical for a V-shaped engine). A single turbine with variable guide vanes is installed in the camber of the cylinder block.

The motor has an aluminum body with intersecting struts. The cylinders in it are equipped with cast iron sleeves, which contributes to hardening and operational reliability. The connecting rods are steel, and the crankshaft is made of heavy-duty material, with an extensive shaft bearing surface.


Engine’s type diesel
Production years 03/2005
Power output, kW at rpm 140-170 at 3800
Power output, hp at rpm 190-231 at 3800
Displacement, cc 2987
Number of cylinders 6
Valves 24
Compression ratio 18.0:1
Cylinder bore, mm 83
Piston stroke, mm 92
Crankshaft bearings 4
Configuration V6
Fuel type diesel
Fuel system direct fuel injection Common Rail 3
Turbine VTG with variable turbine geometry
Euro standards Euro-4
Cylinder head DOHC
Timing mechanism chain
Cooling water

The engine crankcase is made of die-cast aluminum with a through cross strut and gray cast iron cylinder liners to help reduce engine weight. The injectors are designed as 8-hole nozzles. Optimized airflow intake and charge tracts improve charge changeover. The charge air cooler allows the charge air temperature to be reduced to 95 ° C.

Piezo injectors allow up to 5 injections per cycle. This helps to reduce engine noise while improving responsiveness and dynamics. The VTG turbocharger delivers both high power and high torque even at low revs. Electrically regulated turbocharger provides fast and accurate boost pressure control, keeping metering and boosting errors to a minimum
Engine Mercedes OM642 under the hood
Features of engine injectors:

  • injection is controlled by the electronic control unit;
  • injectors are made in the form of nozzles, have eight holes;
  • pressurization is provided by a VTG compressor with variable turbine length;
  • the intake manifold is equipped with an additional air duct;

To improve environmental performance, a cooled exhaust gas recirculation (AGR) system is used. Several details are involved in the operation of this system:

  • the filter is restored without using additional elements;
  • Selective catalyst traps ammonia from diesel combustion, preparing the substance for a further reduction reaction;
  • at the same time SCR acts as a filter that traps odors of sulfur, etc.

Frequent problems

A bunch of all kinds of sensors, adjustable air flow, the ability to relieve excess pressure – all this does not guarantee the trouble-free operation of the unit. If you are not careful about the cleanliness of the engine, it may not reach the end of its service life. OM 642 is characterized by some “sores” that are inherent in all diesel engines:

  • intake manifold soiled;
  • jammed EGR valve;
  • jamming and breakage of the draft of the vortex dampers;
  • oil leak from under the heat exchanger;
  • cracked steel exhaust manifold;
  • faulty fuel injectors.

Explanation of marking

OM Diesel ICE
642 Engine type: 6-cylinder V-arrangement.

In general, the V-shaped diesel “six” turned out to be quite reliable and unpretentious. She does not even come close to the problems that arose on gasoline engines produced at the same time and installed on the same cars.

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