01/08/2021
The Mercedes Benz ML Class vehicles equipped with the OM642 diesel engine, from 2007 to 2020 suffers from a major design defect, that is the CCV (crank case ventilation) system. As early as 80,000 kilometers, heavy smoking, heavy oil leaks, increased fuel consumption, lack of power, black soot filled areas at and around the Exhaust tail pipes, increased engine temperatures, Particle filters and EGR valve blockages along with check engine light and severe burning of the eyes. All of this is caused by the inefficient ventilation system. As the engine ages, the blow-by increases and overwhelms the capacity of the ventilation device. As a result oil mist in the blow-by is sucked out of the head by the powerful turbo charger at the intake. This oil passes through the turbo charger and sent to the intercooler. The compressed air with it's oil mist is sent through the throttle system to the left and right intake manifold, as pictured below. This oil mist combination also find its way into the EGR cooler and thus the EGR valve. The soot in the EGR system, mixes with this oily mix, creating heavy sludge in the intakes. This stuff enters the combustion chambers, where it creates problems for the piston rings and the cylinder walls. Eventually, this toxic stuff bypasses the piston rings and enters the crankcase, further compounding the crankcase pressures and increasing blow-by. Increase crankcase pressures will destroy engine seals, including the oil cooler seals. The turbocharger itself may not survive. The engine bearings may not survive. The engine itself can be destroyed. The only solution is to strip and clean the entire upper section of the engine, the intake manifolds and everything in the V of the engine. New parts must be fitted, including the EGR Valve, the EGR Cooler may be possible to clean, if not a new one must be installed. The plastic linkages for the Servomotor flaps must go as well, replaced with the aftermarket aluminum. The Servomotor, if jammed must be replaced. The turbocharger must be carefully accessed and replaced if unsatisfactory. Finally, a method must be found to, regenerate, physically clean or replace the very expensive Particle Filter. A catch can must be installed between the tube leading from the CCV behind the right side cylinder head, to the Intake at the turbocharger. This will trap the oil and ensure only, oil free gasses, are present at the turbo intake. There is just no easy solution.