What is this engine knocking noise?
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
What is this engine knocking noise?
Noise starts about 5s into the mp3. Car is completely idle in park. I only notice this when coming to a stop or completely stopped and it randomly starts, slows down, stops, speeds up, goes away, comes back, etc. It always seems to go away after accelerating though. From inside the car it sounds like its coming from the driver side valve covers, I can't really hear it at all (or I can't get it to do it) when the hood is open.
I found a bunch of other threads someplace about faulty piston boring or rings or something on certain vins for w221s, but my vin falls outside of that range.
Thanks for any help
I found a bunch of other threads someplace about faulty piston boring or rings or something on certain vins for w221s, but my vin falls outside of that range.
Thanks for any help
Newbie
Joined: Oct 2022
Posts: 9
Likes: 0
2010 E500
Which engine does your car have?
Whats the ages on the idler pulleys?
Engine & trans mounts?
I also have a noise Im tyring to track down but it's not the same as yours. I've done the pulleys and the tensioner, Some how car still has original 2010 engine mouts
I have the M273.
Whats the ages on the idler pulleys?
Engine & trans mounts?
I also have a noise Im tyring to track down but it's not the same as yours. I've done the pulleys and the tensioner, Some how car still has original 2010 engine mouts
I have the M273.
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
M272, specifically: 272980 31 413216
mounts and pulleys are original but it also only has 97k miles. I bought it at 48k and it's been making this noise since I got it some odd 5 years ago.
There's no engine mount play or vibration, no observable problems and no xentry codes. :/
GL hunting down your sound though!
mounts and pulleys are original but it also only has 97k miles. I bought it at 48k and it's been making this noise since I got it some odd 5 years ago.
There's no engine mount play or vibration, no observable problems and no xentry codes. :/
GL hunting down your sound though!
MBWorld Fanatic!
Joined: Oct 2002
Posts: 4,990
Likes: 1,350
From: Cincinnati
2010 E350 4Matic
M272, specifically: 272980 31 413216
mounts and pulleys are original but it also only has 97k miles. I bought it at 48k and it's been making this noise since I got it some odd 5 years ago.
There's no engine mount play or vibration, no observable problems and no xentry codes. :/
GL hunting down your sound though!
mounts and pulleys are original but it also only has 97k miles. I bought it at 48k and it's been making this noise since I got it some odd 5 years ago.
There's no engine mount play or vibration, no observable problems and no xentry codes. :/
GL hunting down your sound though!
Regarding the balance shaft issue. It was an issue prior to 2008 and was corrected.
Last edited by MBNUT1; Nov 27, 2023 at 11:12 PM.
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
Your engine is a higher serial number than the ones that had block score induced idle knocking. See attachment.. You can hear what that sounds like in the second attachment. It happens when the oil is hot.
Regarding the balance shaft issue. It was an issue prior to 2008 and was corrected.
Regarding the balance shaft issue. It was an issue prior to 2008 and was corrected.
I enjoyed looking up the balance shaft issue, I wasn't aware of it. I skipped the w211, going from w210 to w212 so I've very glad I lucked out on that. Not so glad I have failed piston rings in my gl320 though...
Anyway, thanks for all the help. At least I know its not a bunch of things, but I'm still clueless as to what it might be.
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
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2009 GL320, 2010 E350
Actually reading through it again, did we both make the same mistake and compare my 272 serial number to the 273 serial number? The pdf says it was corrected as of 2729xx 31 932895, which is considerably higher than my 272980 31 413216. However it also says it's mostly on vehicles with production dates of august 2010 to november 2010, mine was november 11 2009. Now I'm wondering if the difference in the audio is from my recording inside the car vs the sample being outside (clearly in a shop).
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MBWorld Fanatic!
Joined: Oct 2002
Posts: 4,990
Likes: 1,350
From: Cincinnati
2010 E350 4Matic
Actually reading through it again, did we both make the same mistake and compare my 272 serial number to the 273 serial number? The pdf says it was corrected as of 2729xx 31 932895, which is considerably higher than my 272980 31 413216. However it also says it's mostly on vehicles with production dates of august 2010 to november 2010, mine was november 11 2009. Now I'm wondering if the difference in the audio is from my recording inside the car vs the sample being outside (clearly in a shop).
Mine has the knock. It is quiet when the engine is cold, but there when the engine is hot. Only present at idle. It has been that way for 10's of thousands of miles. Had a lengthy discussions with another forum member with a M273 his was similar in the it has been there for awhile. Though to be honest I am starting to work on the front end and would hate to invest the time and money to have this deteriorate to the point of becoming an issue. I am at 150K hoping to make 200K. I will tell you it did make me nervous a year ago when I was up in Canada ie far from home and would hear it.
Was your recording at idle? The other thing that is weird from you account, is that you can't hear it outside the car. I don't hear it inside the car but definitely outside the car. For me it seems to be coming from the front passenger side.
The correct way to determine if it is scoring is to get a boroscope and look at the cylinder walls. I have not done this because what I am I going to do with that finding? ( I am assuming that it is present).
Last edited by MBNUT1; Nov 28, 2023 at 01:34 PM.
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Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
I'm right there with you. I read that exact pdf (actually in xentry a couple years ago) and came to the same conclusion, that my serial number was higher somehow. OOPSIES.
Yes it was at idle, and I'm now thinking that the reason I've never heard it outside the car is because I only checked it outside when it was cold. I haven't aggressively tried to hunt it down because I only ever remember it 15 minutes into a drive when I get to the city and start stopping in traffic. Then it exists my mind by the time I get home.
If you're idling does your knocking stay at exactly the same interval (which would be logical given the pistons scraping the walls at the same rpm). Mine specifically will speed up, as it did in my recording at the start, then simply disappear some seconds or a minute or two, then come back sometimes at full speed and sometimes slowly building back up. All of this at idle and in park.
If you're idling does your knocking stay at exactly the same interval (which would be logical given the pistons scraping the walls at the same rpm). Mine specifically will speed up, as it did in my recording at the start, then simply disappear some seconds or a minute or two, then come back sometimes at full speed and sometimes slowly building back up. All of this at idle and in park.
MBWorld Fanatic!
Joined: Feb 2014
Posts: 6,190
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From: MA
2008 E350 4Matic, 2011 E350 4matic
M272, specifically: 272980 31 413216
mounts and pulleys are original but it also only has 97k miles. I bought it at 48k and it's been making this noise since I got it some odd 5 years ago.
There's no engine mount play or vibration, no observable problems and no xentry codes. :/
GL hunting down your sound though!
mounts and pulleys are original but it also only has 97k miles. I bought it at 48k and it's been making this noise since I got it some odd 5 years ago.
There's no engine mount play or vibration, no observable problems and no xentry codes. :/
GL hunting down your sound though!
Out Of Control!!
Joined: Apr 2019
Posts: 12,161
Likes: 6,882
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Serpentine family kit...
The pegged pigeonholed tensioner helps kills the pulleys by letting the belt slip. It heats up and dries remaining specs of light bearing grease. This is well perfected.
Plastic idlers are actually better than metal ones to isolate from belt heat. It sounds cheaper but actually it delivers less premature failure.
Everything must go as a kit (tensioner + belt + idler pulleys) for a chance to save the life of your accessories (compressor, alternator, pump). These are keepers if the tensioner plays fair
.
What is the good German OEM brand of tensioner...???
We know belt is Continental, best rubber mfg in the world.
Plastic idlers are actually better than metal ones to isolate from belt heat. It sounds cheaper but actually it delivers less premature failure.
Everything must go as a kit (tensioner + belt + idler pulleys) for a chance to save the life of your accessories (compressor, alternator, pump). These are keepers if the tensioner plays fair
. What is the good German OEM brand of tensioner...???
We know belt is Continental, best rubber mfg in the world.
Thread Starter
Newbie
Joined: Jul 2011
Posts: 13
Likes: 1
2009 GL320, 2010 E350
Well I finally figured it out, so I'll update for people who find this in the future. Despite writing "check purge value" at the top of my list, I somehow managed to forget to check it a dozen times when I got to the car. I bought a cheap $10 car stethoscope on ebay and WOW I don't know how I've lived without this all these years, it's about 400x better than a screwdriver or dowel. Anyway it led me to the frame near the purge valve, I finally remembered to check the purge value and low and behold it was unclipped from its mount, bouncing around on the AC line.
Stupid lyme brain, literally the first thing I thought to check I just couldn't remember. Anyway case solved.
Stupid lyme brain, literally the first thing I thought to check I just couldn't remember. Anyway case solved.
Out Of Control!!
Joined: Apr 2019
Posts: 12,161
Likes: 6,882
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
slow wins the race
Well I finally figured it out, so I'll update for people who find this in the future. Despite writing "check purge value" at the top of my list, I somehow managed to forget to check it a dozen times when I got to the car. I bought a cheap $10 car stethoscope on ebay and WOW I don't know how I've lived without this all these years, it's about 400x better than a screwdriver or dowel. Anyway it led me to the frame near the purge valve, I finally remembered to check the purge value and low and behold it was unclipped from its mount, bouncing around on the AC line.
Stupid lyme brain, literally the first thing I thought to check I just couldn't remember. Anyway case solved.
Stupid lyme brain, literally the first thing I thought to check I just couldn't remember. Anyway case solved.
How does this part look like... picture?
