OM651 C200 CDI oil leak around the air intake.

[tlgbltcn]

Hello everyone,

I've been checking the engine coolant level for a while since it reduced abnormally recently and if it's reduced I add it up to keep the normal level. Then I realized that there were oil leak signs under the air intake area (passenger side of the engine) as well. These are what I saw at first glance.




When I checked the engine oil level it was at the minimum level so I assumed that the leak could be 1-2 litre approximately. I removed the air intake parts to see it clearly and came across the following.








The most obvious traces appear exactly at the attachment points (in the picture above), but I cannot be completely sure. I suspected an oil separator hose, but everything seemed normal there was no sign of a torn or a deformation.







Do you have any idea as to why this might be happening? I'm still investigating the part that I've removed. There may be a leak in the marked area where the oil separator hose is connected. Thank you in advance.

 

[onefortheroad]

Think most mercs vent the crank case directly to the turbo . You do get oil mist forming , but not an oil leak as such.

 

[tlgbltcn]

Think most mercs vent the crank case directly to the turbo . You do get oil mist forming , but not an oil leak as such.

I want to believe this, but unfortunately, seeing the oil level at a minimum after 2k kilometers of use made me suspicious. I make oil service by myself and haven't seen a sign like that. I believe that something went wrong. The vehicle is currently waiting to be intervened and I will reassemble and observe after the best estimate and repair I can make by myself. I suspect the PCV is not working properly so I'll focus on it.

 

[MinionBob]

I had a similar thing, not an oil leak per se but a light misting of oil where i did not want it. Conclusion was slow, gradual deformation if pipes with age (in the pipework similar to your last photo, circled in green). The new pipework was £130, so I just cleaned it and replaced it.

If oil is going from min to max in 2k, that would be around 1L of oil, so would be a serious leak; I except you would see it. Is there a chance that the light misting of oil you see in the engine bay is not directly related to the loss of 1L oil and this problem is occurring somewhere else?

 

[tlgbltcn]

I had a similar thing, not an oil leak per se but a light misting of oil where i did not want it. Conclusion was slow, gradual deformation if pipes with age (in the pipework similar to your last photo, circled in green). The new pipework was £130, so I just cleaned it and replaced it.

If oil is going from min to max in 2k, that would be around 1L of oil, so would be a serious leak; I except you would see it. Is there a chance that the light misting of oil you see in the engine bay is not directly related to the loss of 1L oil and this problem is occurring somewhere else?

Thank you for sharing your experience. What I've done today, after assembling many things that I removed, before attaching the hoses that direct the airflow (because they take up a lot of space and are very difficult to observe with it), I started the engine and checked for leaks under a little pressure one last time. There doesn't seem to be any problem right now and I think I may have exaggerated the losses in the oil level a little, I may not have waited for the oil to drain completely and it was at the minimum level in the first place. In other words, the oil level was not at a level that would cause a problem and I added it. I'm going to observe the oil level and under the hood often and inform this thread as much as possible. If it doesn't upset me, we will be traveling companions for a long time

 

[mioba]

Intake to turbo seals and pcv seal wear doen due to vibration. Repkace them every few years. A noted pain of the 642 - sure other engines are of similar design.