Mercedes Benz V6 3.0 diesel engine M642 has proven to be a strong and reliable. This engine is used in every Mercedes-Benz platform as well as Jeep, Dodge Sprinter and Freightliner Sprinter. The combination of power, durability and fuel economy makes this engine a superior choice everywhere it is used. The Achilles heel of this engine, unfortunately, is the oil cooler seal design, and intake manifold plastic arms for intake runners. Let’s go over which vehicles are affected, the signs and symptoms of this issue.

Vehicles that are affected by this issue include: 2006-2009 Dodge Sprinter V6, 2010-2015 Mercedes Sprinter V6, 2007-2014 Mercedes E320 & E350 BlueTEC, 2007-2012 Mercedes R Class 320 CDI & 350 BlueTEC, 2007-2016 Mercedes GL 320 CDI & GL 350 BlueTEC, 2007-2014 Mercedes ML 320 CDI & ML 350 BlueTEC, 2007-2015 Freightliner Sprinter and 2007-2008 Jeep Grand Cherokee CRD.

Most of the mechanics who are not familiar with this engine will tell you that you have the rear main seal leaking but that is not the case. First thing you should do is look on the driver side of the engine right by the bell housing there is a small drain hole. If you see oil in that drain hole that means that you have an oil cooler seals leaking. What is happening is that in the valley of the engine between engine heads on top of the block where the oil cooler is located there is a drain hole that drains excessive fluids from the valley. It’s traveling through the back of the engine where the rear main seal plate is located to the drain hole on the left side of the engine.

To correct the issue the two seals on the oil cooler needs to be replaced. The oil cooler does not need to be replaced and just can be reinstalled. The old problematic seals where orange. The new seals are purple which are made out of different material and have a bit different shape.