W166 '12 Bluetec Knocking sound/ Injectors
Thread Starter
Junior Member
Joined: Oct 2009
Posts: 64
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From: New York City
2014 ML63
W166 '12 Bluetec Knocking sound/ Injectors
Hi Everyone, after searching found some similar threads however wasn't exact issue figure let me try fresh and see any new info.
Vehicle Info ; 2012 ML 350 W166 Bluetec 135,xxx miles on it.
Initial issue losing coolant slowly then fast, it end up being a water pump failed, got it replaced all good, same time mechanic replaced the water pump, he noticed carbon build up / leaking diesel fuel of the injectors on the passenger side ( 2nd injector from the front ). he went and cleaned up and replaced the injector . Called me said car ready for pick up, picked it up went to my near my destination left it parked for about 2-3 hours. came back started it and started making some ticking / knocking sounds ( got louder as i accelerating more ) . got home ,parked it and next making the same sound and I had it taken back to the shop and issue still persist month later . I believe the new injector need to be coded and still same issue. and noise is coming only from passenger side of the engine pretty much the area that was worked on.
any advice is appreciated, they suggestion to open up the valve cover trying to avoiding surgery. car was running fine prior and no engine issues minus nox senors 2 years ago. trying upload a sound clip it isn't allowing me some reason.
Thank you ,
Vehicle Info ; 2012 ML 350 W166 Bluetec 135,xxx miles on it.
Initial issue losing coolant slowly then fast, it end up being a water pump failed, got it replaced all good, same time mechanic replaced the water pump, he noticed carbon build up / leaking diesel fuel of the injectors on the passenger side ( 2nd injector from the front ). he went and cleaned up and replaced the injector . Called me said car ready for pick up, picked it up went to my near my destination left it parked for about 2-3 hours. came back started it and started making some ticking / knocking sounds ( got louder as i accelerating more ) . got home ,parked it and next making the same sound and I had it taken back to the shop and issue still persist month later . I believe the new injector need to be coded and still same issue. and noise is coming only from passenger side of the engine pretty much the area that was worked on.
any advice is appreciated, they suggestion to open up the valve cover trying to avoiding surgery. car was running fine prior and no engine issues minus nox senors 2 years ago. trying upload a sound clip it isn't allowing me some reason.
Thank you ,
Last edited by PurpleS500; Nov 15, 2020 at 05:03 PM. Reason: title
Thread Starter
Junior Member
Joined: Oct 2009
Posts: 64
Likes: 0
From: New York City
2014 ML63
I had the car for several years , worked fine, and familiar sound of the diesel sound. as i rev makes a louder clicking / knocking sound, and it coming from the passenger side of the engine / valve cover area, where one of the injectors was replaced and fast forward no good news until today, few others been taking look at it and many mechanics saying cant pin point the issue. 
Out Of Control!!
Joined: Sep 2018
Posts: 14,671
Likes: 4,574
From: unbegrenzt
2017 GLE350 4MATIC
There are others on this site who are more knowledgeable than I am on this engine. It sounds like it could be the timing chain. Have you used the search feature on this site? Search for OM642.
Senior Member
Joined: Feb 2018
Posts: 482
Likes: 140
GLK250 ML350
Did your mechanic check the other injectors? If one is leaking, chances are all of them are leaking. And you are correct, you have to code the injectors after replacement. It sounded normal to me when i listened on YouTube. Are you experiencing power lost? Lots of smoke?
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Joined: Jun 2023
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w166
Mr
Hi Everyone, after searching found some similar threads however wasn't exact issue figure let me try fresh and see any new info.
Vehicle Info ; 2012 ML 350 W166 Bluetec 135,xxx miles on it.
Initial issue losing coolant slowly then fast, it end up being a water pump failed, got it replaced all good, same time mechanic replaced the water pump, he noticed carbon build up / leaking diesel fuel of the injectors on the passenger side ( 2nd injector from the front ). he went and cleaned up and replaced the injector . Called me said car ready for pick up, picked it up went to my near my destination left it parked for about 2-3 hours. came back started it and started making some ticking / knocking sounds ( got louder as i accelerating more ) . got home ,parked it and next making the same sound and I had it taken back to the shop and issue still persist month later . I believe the new injector need to be coded and still same issue. and noise is coming only from passenger side of the engine pretty much the area that was worked on.
any advice is appreciated, they suggestion to open up the valve cover trying to avoiding surgery. car was running fine prior and no engine issues minus nox senors 2 years ago. trying upload a sound clip it isn't allowing me some reason.
https://youtu.be/tT_hKVA7Rxo
Thank you ,
Vehicle Info ; 2012 ML 350 W166 Bluetec 135,xxx miles on it.
Initial issue losing coolant slowly then fast, it end up being a water pump failed, got it replaced all good, same time mechanic replaced the water pump, he noticed carbon build up / leaking diesel fuel of the injectors on the passenger side ( 2nd injector from the front ). he went and cleaned up and replaced the injector . Called me said car ready for pick up, picked it up went to my near my destination left it parked for about 2-3 hours. came back started it and started making some ticking / knocking sounds ( got louder as i accelerating more ) . got home ,parked it and next making the same sound and I had it taken back to the shop and issue still persist month later . I believe the new injector need to be coded and still same issue. and noise is coming only from passenger side of the engine pretty much the area that was worked on.
any advice is appreciated, they suggestion to open up the valve cover trying to avoiding surgery. car was running fine prior and no engine issues minus nox senors 2 years ago. trying upload a sound clip it isn't allowing me some reason.
https://youtu.be/tT_hKVA7Rxo
Thank you ,
hello, did you manage to resolve that ticking/clicking sound on your w166. I pretty much have the same issue. Please advise
