Strange chirping noise from engine while coasting.

Sep 14, 2011 | 11:27 PM

Bernie (OOParts

Thread Starter

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Joined: May 2007

Posts: 24

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Strange chirping noise from engine while coasting.

A really odd sound has been coming from the engine. Sounds like crickets. It only occurs when I let go of the gas pedal on my 2008 ML63 and only occur when slowing down from 40 to10mph. Below 10mph the sound stops and the sound never occurs until the car is less than 40mph. It'll happen whether the car is just coasting or actually braking. Neutral or drive transmission no change. Interestingly, it usually happens after 5-10 min warmup. When cold, there is no noise.

Here is a youtube video of the sound I made...

http://www.youtube.com/watch?v=NKKeRUNp5fs

Took it to the dealer and they replaced the engine idler pulley and drive belt... but no effect.

Any ideas?

Oct 5, 2011 | 08:26 AM

schmick325

Senior Member

Joined: Jul 2010

Posts: 288

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From: Brisbane, Australia

RR Evoque Dynamic, Benz Valente (work hack)

Strange noise.

Maybe put it on a dyno and see if it does it. May also give you a chance to isolate the noise.

Oct 5, 2011 | 08:46 PM

Maverick1975

MBWorld Fanatic!

Joined: Mar 2007

Posts: 2,155

Likes: 14

From: Sydney, Australia

Vath ML63 Brabus C63 SL63 CLK63BS C63BS

Jeez i wish i could help you but have never heard of anything like that. Scares me that the mechanics at MB have no clue

Oct 20, 2011 | 08:56 AM

ONEFASTE55

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Joined: Jan 2005

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From: NEW JERSEY

2015 MERCEDES ML63-AMG

Check your serpentine belt and also the fan. Sometimes a bent fan blade can cause that. Good luck!

Oct 23, 2019 | 01:27 AM

Maverick1975

MBWorld Fanatic!

Joined: Mar 2007

Posts: 2,155

Likes: 14

From: Sydney, Australia

Vath ML63 Brabus C63 SL63 CLK63BS C63BS

Quote:

Originally Posted by Bernie (OOParts

Did you ever identify this? I have exact same noise under exact same conditions in my ML63

Dec 9, 2019 | 06:01 AM

Maverick1975

MBWorld Fanatic!

Joined: Mar 2007

Posts: 2,155

Likes: 14

From: Sydney, Australia

Vath ML63 Brabus C63 SL63 CLK63BS C63BS

Quote:

Originally Posted by Maverick1975

Did you ever identify this? I have exact same noise under exact same conditions in my ML63

turns out it was the bearings in several of the pulleys, failing after 58,000kms. Replaced 4 I think it was me noise appears from be gone

Jan 5, 2020 | 07:13 PM

Maverick1975

MBWorld Fanatic!

Joined: Mar 2007

Posts: 2,155

Likes: 14

From: Sydney, Australia

Vath ML63 Brabus C63 SL63 CLK63BS C63BS

Quote:

Originally Posted by Maverick1975

turns out it was the bearings in several of the pulleys, failing after 58,000kms. Replaced 4 I think it was me noise appears from be gone

Noise was gone for about a day but after a longer drive returned so clearly not the pulleys!

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Oct 27, 2020 | 03:51 PM

icat0963

Newbie

Joined: Jun 2020

Posts: 8

Likes: 0

W211 E63

For anyone else that stumbles upon this, the cause in my case was the PCV valve, also referred to as the breather valve. Relatively low cost and pretty straight forward to replace.