MERCEDES 3.0 CDI ENGINE (OM642)
Engine Rebuild
Common Mercedes 3.0 CDI Engine Failures
The Mercedes 3.0 CDI engine (OM642) is a common engine fitted to a large array of vehicles. This platform suffers from a variety of issues in various configurations.
Fitted to the C class, E class, GLK, G class, ML, GL, S class, CLS, R class, Sprinter, X class, Vito and in addition to these the Jeep Grand Cherokee and Chrysler 300C
Known Failures
We find that this engine is generally strong and well built, however most commonly we find engines have not had correct and regular maintenance. Because of this we have discovered spun bearings, both mains and conrod. This is due to components not getting the lubrication they need to operate, generally caused by blocked galleries and pickup. When a failure occurs it is usually indicated audibly by a knocking engine. The updated version of the 3.0 CDI engine has only a single width timing chain as opposed to the earlier double chain. This makes the later version more susceptible to timing failure. Because its reduction in strength means it is more likely to stretch and break.
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We have found some fuel injectors fitted to the Mercedes 3.0 engine have proven to over-fuel. This means the injector itself is injecting too much fuel inside the cylinder. So they produces an extreme amount of heat as the large amount of fuel is compressed and ignited. Over-fuelling fuel injectors we find in the 3.0 CDI engine cause the piston to melt and reduce because of the extremely high heat it is subjected to. So of course due it’s reduction in size and broken off pieces changing the shape the piston. It is rendered useless as there is little to no compression or seal in the cylinder. A common audible recognition of this failure is a knocking engine. The debris this creates also causes damage.
Mercedes 3.0 CDI OM642 Engine Rebuild
MERCEDES 3.0 CDI ENGINE
OM642 hISTORY
Engine History
The Mercedes 3.0 engine was first released in 2005 as a replacement for the 5 & 6 cylinder straight engines used prior. The platform was also used by Dodge, Jeep and Chrysler in various vehicles. The OM642 engine has been updated numerous times over the years, The engine is still in use on current production models from Mercedes.
