E400 2016 knocking sound at idle
#1
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E400 2016 knocking sound at idle
My e400 2016 I bought recently with 40k miles has developed this knocking sound at idle. It usually happens when I push the car in sport mode and stop at a red light. It’s a consistent knocking sound that only happens at operating temp at idle in drive and never when the cars cold. I am using only shell v power 93 octane so I’m guessing it might have something to do with the spark plugs but am not too sure and need some help.
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2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
USA octane is AKI, its actually higher.
If you are in USA, then it should be fine using octane 93.
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pierrejoliat (12-19-2021)
#4
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yeah I have that wastegate noise when I accelerate under load but this knocking just sounds like something completely different it only happens at idle too, I don’t think the wastegate would make a knocking noise at idle
#5
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Which country are you located at ? When you speak of octane a 93 oustide USA, say in Europe and Asia ( I don't know Canada ) it is RON 93 and our E400 at least for my country version need RON 95 but I use RON 98.
USA octane is AKI, its actually higher.
https://youtu.be/zf-OYXlhJis
If you are in USA, then it should be fine using octane 93.
USA octane is AKI, its actually higher.
https://youtu.be/zf-OYXlhJis
If you are in USA, then it should be fine using octane 93.
#6
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The car itself runs perfect though no engine hesitation and I do occasionally see white smoke from exhaust while I’m at a red light and the coolant isn’t leaking whatsoever so I’m guessing maybe emission related thing, fuel pump, spark plug causing the knocking? I doubt a lifter or rod would go bad on a Mercedes and I got a recent oil change using 5w40 molly which didn’t make a difference in the knocking. I’m also starting to think maybe loose heat shield
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2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
If you want to test for iginition knocking, use manual gear mode , set to highest gear, keep it as low RPM as possible and full throttle......... ignition knock is more obvious if pushed this way
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#8
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I tried that and nothing really sounded out of the normal, I heard from another forum that the dealer said this noise is due to loose wastegate for the turbos. It’s weird because the noise comes and goes during every fillup. These past few days I have been also seeing excessive exhaust smoke compared to other cars at idle during freezing temperatures. I guess the trip to the dealer is coming sooner than I thought
#9
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If you're only seeing steam coming from your exhaust when it's cold out and everyone's car is doing it, I wouldn't worry about it. Some cars kick out steam like a stadium fog machine, and others don't. It can even vary on an individual basis. However, if you're seeing steam consistently, then you have something like a coolant leak.
That said, the knock is worrisome. Definitely get it addressed. Good luck!
That said, the knock is worrisome. Definitely get it addressed. Good luck!
#10
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If you're only seeing steam coming from your exhaust when it's cold out and everyone's car is doing it, I wouldn't worry about it. Some cars kick out steam like a stadium fog machine, and others don't. It can even vary on an individual basis. However, if you're seeing steam consistently, then you have something like a coolant leak.
That said, the knock is worrisome. Definitely get it addressed. Good luck!
That said, the knock is worrisome. Definitely get it addressed. Good luck!
#11
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If the knock happens at idle, I would probably rule out anything to do with spark knock (pre-ignition), as this only happens when the engine is under load. At idle, it can't be under load, so your noise must be something else.
Also, if it was the plugs, I would expect CIL or error codes to show up. Yes, it could be a physically damaged plug, coil, or other ignition part which is really arcing to ground - but again, I would expect an error or fault code.
You should still be under factory warranty, so I would let the dealer deal with it.
Also, if it was the plugs, I would expect CIL or error codes to show up. Yes, it could be a physically damaged plug, coil, or other ignition part which is really arcing to ground - but again, I would expect an error or fault code.
You should still be under factory warranty, so I would let the dealer deal with it.
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#12
I’ve got the same issue. Rhythmic clacking that goes away with engine revving. Not noticeable until after engine warmup but only then at idle. Seems to have become more pronounced with car being used less due to working from home. Definitely not related to engine knock. Definitely not transmission related. Almost sounds like metal or a belt contacting a plastic cover. Did anyone definitively figure this out? I pointed it out at last service and of course the dealer didn’t hear it and said all was normal.
#13
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The dealer said it was normal and since then I’ve been driving the car normally with no issues. I would assume maybe a loose heat shield tapping the engine?
#14
The sound is definitely not normal which irritates me. It is laziness on my part and the dealership not to get to root cause. The question is who wants to pay until the issue is found. I just need to know what if it is serious like a timing chain loose or minor like a cover flapping. I just wish that when you pay $200 for an A service (glorified oil change and checklist) and you report the noise that you get a highly trained service tech to address the problem in writing and document it. By denying the noise itself or calling it normal which we all know it isn’t (otherwise why would we post here) for a vehicle under warranty you just have to wonder if we are all going to get a larger bill later because we’ve ignored a noise that could have been corrected earlier and under warranty.
#16
I have read that there have been some issues with cam chain tensioners in these cars, so you will need to have it looked at. More than one tensioner has been replaced to solve this issue. At idle, the hydraulic tensioners react to the lower oil pressure by reducing the tension on the chain. If the tensioner is leaking, it can release too much pressure and the chain will rattle.
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Applicable bulletins released by MBUSA, see attachments.
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My engine falls in that segment for improved tensioners...is there a way to see if it has been done without going to the dealership? Dont want to set off alarms...but my car came with a 90 day/4k mile warranty and would like that "fixed" if I can under warranty.
Thanks!
Chris
Thanks!
Chris
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2008 E350 (W211 @170K), 2012 ML350 (W166 @119K), 2014 E350 (W212 @100K), 2015 ML350 (W166 @96K)
Without physical evidence, say opening the timing covers, the only thing would be to have access to your car VMI at an MB stealership. The latter assumes the service records are up to date.
Do you already have a reputable/trustworthy Indy in mind for future service?
Do you already have a reputable/trustworthy Indy in mind for future service?
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2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
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Last edited by S-Prihadi; 12-21-2021 at 03:15 AM. Reason: WRONG INFO
#23
As much as everyone hates reviving an age old thread .. I didn't want to start a new one. Did anyone ever find a solution to this? My '16 E400 has now started doing this and it's driving me crazy. Love the car .. hate the knock at idle. On our dinner date last night that wife started commenting on it so I started searching today and found this thread.
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TSB
As much as everyone hates reviving an age old thread .. I didn't want to start a new one. Did anyone ever find a solution to this? My '16 E400 has now started doing this and it's driving me crazy. Love the car .. hate the knock at idle. On our dinner date last night that wife started commenting on it so I started searching today and found this thread.
#25
How do you like the TSB knowledge by @konigstiger under post #17 ?