Momentary knock/tap like noise on a hot start m278
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2014 E550
Momentary knock/tap like noise on a hot start m278
Hi guys, 2014 e550, m278. I've noticed sometimes on a hot start the car has a... Knock or tapping noise. Not a chain rattle. And lasts about 2 seconds and it's gone. Cold starts it's never there. There is 0 chain noise or rattles. It usually takes having to sit for a hour or so hot and it'll do it sometimes. If it sits for 3 or so and has started to cool down, it doesn't seem to do it. So seems to me it's about engine being at hottest temp
I read about can adjusters but most videos I find are of a rattle noise?
Edit: found this video on YouTube. It sounds about the same, perhaps cam adjusters?
https://youtu.be/QO5TcQBOhJM?si=dApBNsjA7gXuCuGt
Thoughts? No codes either.
I read about can adjusters but most videos I find are of a rattle noise?
Edit: found this video on YouTube. It sounds about the same, perhaps cam adjusters?
https://youtu.be/QO5TcQBOhJM?si=dApBNsjA7gXuCuGt
Thoughts? No codes either.
Last edited by Octan3; Apr 5, 2024 at 11:45 PM.
Out Of Control!!
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
up for timing repair
Hi guys, 2014 e550, m278. I've noticed sometimes on a hot start the car has a... Knock or tapping noise. Not a chain rattle. And lasts about 2 seconds and it's gone. Cold starts it's never there. There is 0 chain noise or rattles. It usually takes having to sit for a hour or so hot and it'll do it sometimes. If it sits for 3 or so and has started to cool down, it doesn't seem to do it. So seems to me it's about engine being at hottest temp
I read about can adjusters but most videos I find are of a rattle noise?
Edit: found this video on YouTube. It sounds about the same, perhaps cam adjusters?
https://youtu.be/QO5TcQBOhJM?si=dApBNsjA7gXuCuGt
Thoughts? No codes either.
I read about can adjusters but most videos I find are of a rattle noise?
Edit: found this video on YouTube. It sounds about the same, perhaps cam adjusters?
https://youtu.be/QO5TcQBOhJM?si=dApBNsjA7gXuCuGt
Thoughts? No codes either.
-- Loud like a VVT
-- Short like a tensioner
How old are your secondary tensioners ??
Manually rotate CC to check if any of your VVT are unlocked and in particular Bank1 intake.
No ECU code is a good thing.
(VVT = Cam adjusters)
Oil pressure plays a central role in this issue.
Try to keep oil change interval shorter to preserve viscosity
Use an approved oil at least 5w40
Last edited by CaliBenzDriver; Apr 6, 2024 at 01:02 AM.
Thread Starter
Junior Member
Joined: Jun 2023
Posts: 53
Likes: 14
2014 E550
What I hear is loud but short!
-- Loud like a VVT
-- Short like a tensioner
How old are your secondary tensioners ??
Manually rotate CC to check if any of your VVT are unlocked and in particular Bank1 intake.
No ECU code is a good thing.
(VVT = Cam adjusters)
Oil pressure plays a central role in this issue.
Try to keep oil change interval shorter to preserve viscosity
Use an approved oil at least 5w40
-- Loud like a VVT
-- Short like a tensioner
How old are your secondary tensioners ??
Manually rotate CC to check if any of your VVT are unlocked and in particular Bank1 intake.
No ECU code is a good thing.
(VVT = Cam adjusters)
Oil pressure plays a central role in this issue.
Try to keep oil change interval shorter to preserve viscosity
Use an approved oil at least 5w40
As far as I know everything should be factory/ stock. It's a 2014, Looking at the chain it appears to have the updated design with the "fat" links.
the odd thing is, everybody talks about a rattle or noise on cold start, My cold start is fine, The car sat for 4 months over the winter and fired right up with out a noise, EXCEPT the typical wastegate rattle. Car only does it hot and after sitting for a bit sometimes as mentioned.
I cannot speak too much on the previous owners of this vehicle but it has 100k km on it now. I know for sure in the past 20k km It's had 3 oil changes. I just did one "just because" when I got it about 3000km ago.
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
CC =counter- clockwise rotation
but we must turn CW clockwise for our engine
Oh oh oh..... that is VVT sprocket rattle = $$$
Exact same as my friend's M271, but his a bit louder .
The video you linked...........
but we must turn CW clockwise for our engine
Oh oh oh..... that is VVT sprocket rattle = $$$
Exact same as my friend's M271, but his a bit louder .
The video you linked...........
Thread Starter
Junior Member
Joined: Jun 2023
Posts: 53
Likes: 14
2014 E550
CC =counter- clockwise rotation
but we must turn CW clockwise for our engine
Oh oh oh..... that is VVT sprocket rattle = $$$
Exact same as my friend's M271, but his a bit louder .
The video you linked...........
https://youtu.be/QO5TcQBOhJM
but we must turn CW clockwise for our engine
Oh oh oh..... that is VVT sprocket rattle = $$$
Exact same as my friend's M271, but his a bit louder .
The video you linked...........
https://youtu.be/QO5TcQBOhJM
Gotcha, yeah when I heard it I was figuring that I have a bad cam actuator that's not locking... Interesting how it only does it hot. Most people I read say cold. I'd think oil drain back but then it would do it too when cold and it never does lol.
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
Well by sound and duration, the knock-knock sound is not as bad as my friend's, so I guess his is mechanically worse than yours.
The engine oil pump solenoid when engine at COLD START does not activate, that gives you maximum engine oil pressure.
However, when engine is already warm/hot, the oil solenoid get triggered to purposely reduce oil pressure.
That maybe the reason during cold start you do not get the knock-knock sound
But, if your engine stay OFF for say 3 weeks, maybe knock-knock sound can happen.
The engine oil pump solenoid when engine at COLD START does not activate, that gives you maximum engine oil pressure.
However, when engine is already warm/hot, the oil solenoid get triggered to purposely reduce oil pressure.
That maybe the reason during cold start you do not get the knock-knock sound
But, if your engine stay OFF for say 3 weeks, maybe knock-knock sound can happen.
Thread Starter
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2014 E550
Well by sound and duration, the knock-knock sound is not as bad as my friend's, so I guess his is mechanically worse than yours.
The engine oil pump solenoid when engine at COLD START does not activate, that gives you maximum engine oil pressure.
However, when engine is already warm/hot, the oil solenoid get triggered to purposely reduce oil pressure.
That maybe the reason during cold start you do not get the knock-knock sound
But, if your engine stay OFF for say 3 weeks, maybe knock-knock sound can happen.
The engine oil pump solenoid when engine at COLD START does not activate, that gives you maximum engine oil pressure.
However, when engine is already warm/hot, the oil solenoid get triggered to purposely reduce oil pressure.
That maybe the reason during cold start you do not get the knock-knock sound
But, if your engine stay OFF for say 3 weeks, maybe knock-knock sound can happen.
That video is not mine however just found it had the same kind of tap/knock noise.
I'll try to catch the sound when I can and add it to this forum post but From what I gather It's likely somehow the camshaft actuator not locking then rattles on start up. Even when the car sat for 4 months, first start it sounded "normal" never made a noise or cam chain rattle. other than, again, wastegate rattle.
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Out Of Control!!
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
I disconnected the oil pump solenoid, I was getting the same sound at times last summer too.
That video is not mine however just found it had the same kind of tap/knock noise.
I'll try to catch the sound when I can and add it to this forum post but From what I gather It's likely somehow the camshaft actuator not locking then rattles on start up. Even when the car sat for 4 months, first start it sounded "normal" never made a noise or cam chain rattle. other than, again, wastegate rattle.
That video is not mine however just found it had the same kind of tap/knock noise.
I'll try to catch the sound when I can and add it to this forum post but From what I gather It's likely somehow the camshaft actuator not locking then rattles on start up. Even when the car sat for 4 months, first start it sounded "normal" never made a noise or cam chain rattle. other than, again, wastegate rattle.
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Thread Starter
Junior Member
Joined: Jun 2023
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2014 E550
MBWorld Fanatic!
Joined: May 2018
Posts: 6,600
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
Well, that is basically still fresh oil.
My friend's M271.860 will make knock sound if engine kill say 3 ish hours or more, even if engine still warm
My friend's M271.860 will make knock sound if engine kill say 3 ish hours or more, even if engine still warm
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2014 sl550
My 14 sl550 with m278. Car has 78k miles.
my indy who i trust said not to worry as long as it doesnt get any longer or louder
makes this ticking noise only at warm starts after sitting sometime.
nothing at cold start
my indy who i trust said not to worry as long as it doesnt get any longer or louder
makes this ticking noise only at warm starts after sitting sometime.
nothing at cold start
Last edited by toi; Jul 16, 2024 at 02:46 PM.
Thread Starter
Junior Member
Joined: Jun 2023
Posts: 53
Likes: 14
2014 E550
My 14 sl550 with m278. Car has 78k miles.
my indy who i trust said not to worry as long as it doesnt get any longer or louder
makes this ticking noise only at warm starts after sitting sometime.
nothing at cold start
https://youtu.be/UI9dGt018eA?si=e5YVLjJ4kY2oo6JJ
my indy who i trust said not to worry as long as it doesnt get any longer or louder
makes this ticking noise only at warm starts after sitting sometime.
nothing at cold start
https://youtu.be/UI9dGt018eA?si=e5YVLjJ4kY2oo6JJ
That's the exact same sound I have too. I couldn't catch it. Doesn't happen all the time and when I think it would it doesn't.
I kinda wonder or suspect maybe the cam phasers are leaking out oil like missing one way check valves... But wonder if anybody actually knows.
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Joined: May 2015
Posts: 4
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R129 SL320
CC =counter- clockwise rotation
but we must turn CW clockwise for our engine
Oh oh oh..... that is VVT sprocket rattle = $$$
Exact same as my friend's M271, but his a bit louder .
The video you linked...........
https://youtu.be/QO5TcQBOhJM
but we must turn CW clockwise for our engine
Oh oh oh..... that is VVT sprocket rattle = $$$
Exact same as my friend's M271, but his a bit louder .
The video you linked...........
https://youtu.be/QO5TcQBOhJM
Driven 15k kms after cam tensioners replaced. Also oil pressure selonoid disconnected and changed oil 2k kms ago with Mobil 1 5w-50. I know this is out of spec but my indy recommended this viscosity to avoid this rattle but nothing changed.
