OM642 3L Diesel Turbo Chatter / Surge and PCV leak.



Hi all - I have an R class which shares the same engine with quite a few GL’s so I though I’d post here to see if anyone has seen this issue.

Over the past couple of months I’ve taken this time to do a massive overhaul of my 2010 R300 CDI with the OM642.



It has hit 140k kms and i’ve had it for 90k kms of those. Up until recently, I didn’t notice any turbo surge/chatter when letting off the accelerator and it is really annoying me! I am also getting lots of blowby (as you can see in the video).



Firstly I have changed over my COMAND unit to a Kenwood double din and am waiting for the MOST amplifier converter so there is no music in the car currently. Maybe that is why I’m hearing all these sounds!



Re the overhaul, I’ve done, Lower ball joints, front airbag, front rotors/brake pads, transmission fluid, transfer case and both diffs and std engine oil and filter change.



Videos of the Turbo chatter / surge with intake on and off.



Intake on




Intake off




I originally thought the sound was drivetrain related (given the recent drivetrain work) but that was quickly dismissed as it happened in park/neutral. I then narrowed it down to turbo surge. I pulled the intake pipe from the front of the car and put my ear to it and it is definitely turbo surge.



Does anyone notice the surge in their cars (with the sound system off). It is prominent when lifting off at 1500 rpms plus revs (I guess when the turbo starts spooling). It is reverberating in the airbox and creating a grinding like sound but only sounds like that because of the reverberation in the intake system.



In the second clip you can see there is no grinding/whooshing sound with the air intake off.



Im thinking the surge has always been there but masked by the stereo, or it has recently started because of a Faulty turbo actuator - not opening fully/quickly when lifting off at low boost (see the video with the intake pipe off.



You can see the actuator moving much higher when the turbo is spooling at 2500 rpms to slow it down, compared to the small movement when revved to 1500rpm.



Im thinking if the exhaust side isn’t slowed, this will continue to create pressure in the intake valve which has no where to go except for out the intake system causing the noise.



I think the PCV issue is unrelated and is caused by putting too much oil in at the last change creating excess pressure which has blown the o-ring seals (new one was ordered a month ago but has been delayed due to Covid). Its also the first time ive used non MB spec oil (I put in 5-40 Penrite)… I wonder if that has contributed…



Does anyone notice this sound when lifting off after the turbo has spooled or have any ideas what could be causing the surge?



I know this is a common engine but I can’t locate this issue across any other make/model forums.

 

I am experiencing the same issue now on an ML320 CDI. No CEL power is a bit down. Before this issue started the DPF was cleaned out all sensors replaced. About a month ago the turbo actuator failed, I replaced it with one off Amazon that seemed to have good reviews and matched the exact part to what other members what used as a replacement. Now I have boost again but still jerks when driving at low RPM and barely giving it throttle. When the 164 is in boost she has no problems. However when I come to stop or slow down to below 10 MPH I can hear the turbo surge loudly. Going to place the PCV next as I noticed it is leaking. I didn't find any oil on the turbo, have excessive consumption or any broken seals from the air intake. My indy who is was an MB master tech has no idea and thinks I'm crazy as when he test drives it the vehicle stays in boost and you have no issues. Only other thing I could think that might be causing the jerking at low RPM is the fact I need to rebuilt the entire front end of the SUV. My ball joints are shot, tie rods need replacing, shocks all around, and apparently I have a failing steering that needs to be replaced. Knowing these cars have so many sensors I figured it might a safe fail from the drivetrain geometry not matching the spec it needs to be in causing the computer to cut boost creating the surge. I've notice this is becoming a common issue with these engines reaching this mileage at this age but no one seems to have an actual answer to resolving the issue. Best of luck and if you have any updates I'd love to know what you've learned so far.

 

I’ve mainly been told this is normal for the engine (as it ages?).

I replaced my intake pipe that wasn’t sealing properly and that has dampened the noise a lot.

Ive also been told by another person that they changed their actuator and it fixed the problem (they tried an aftermarket and a new one). Can’t remember which one they said worked. I’ve also read the actuator needs to be coded to the car.

As for suspension, I doubt it would have any sensors to modify the engine behavior. I’ve had bad struts, worn lower ball joint and sway bar end links and I don’t get any jerking. I suspect it is all engine related.

 

Hi Onnzo, I've read about the Chinese turbo actuators being hit or miss. I replaced my original Hella one with one of the Chinese ones since I needed to get the car out of limp mode and it did the trick. I've read from other members that the original actuators fail typically from a solder connection failing on the inside and you can typically fix the the issue just by opening it up and soldering the broken connection. I'm going to give that a try next...

Since my last post I replaced the PCV and had to replace the air intake as it was broken beyond repair my indy must have over torqued the couplings breaking the plastic and the boots were also ripped. Of course that didn't fix anything but at least is one less thing to worry about and I can rule out any MAF issues just as well. I cleaned out the EGR pipe which to my surprise was relatively clean and had little built up. The SUV just broke 130K miles and mainly did 140 miles daily commutes doing 80+ along with some "spirited driving" (gotta use all of the boost am I right) which I think helped keep it clean along with only using the same Shell gas station and proper oil. Just dropped new air filters in as well so going we'll see what I find next. It's a shame several of us with the OM642 have experienced these issues and it seems like no mechanic can figure it out.

What I have noticed now with all of the recent work I did is that now the surging has quite down a good amount but the bucking is still there. Now the truck just bucks when letting off the throttle and replying light gas. Where you able to resolve your problem? I'm starting to wonder if this is possible a fuel issue with either injectors that are clogged but doubt my self as the fuel mileage is still the same as it was when we first got the truck and under heavy/ WOT there is no hesitation or lack of power.

 

I’ve never had any bucking so I can’t comment on that. If your fixed the air side, the next logical step would be to check the fuel side as a cause of the bucking.

I recently found that the connections to my catch can were loose and have tightened them. It was leaking oil all over the place and I thought it was the rear main seal. Haven’t had a chance to see if that quietens the surge.

I also did open up my actuator and all was good there. There was oil in there which I cleaned up (from the turbo intake not sealing fully) but otherwise it was ok.

Im close to 150k kms on mine and hopefully it lasts a lot longer!

 

did you manage to get this sorted??