Bernie (OOParts

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?

schmick325

Strange noise.

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

Maverick1975

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

ONEFASTE55

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

Maverick1975

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

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

Maverick1975

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

icat0963

Did you ever figure this out? Mine just started doing it after I replaced the fuel injectors. I have a feeling it has something to do with the intake/intake manifold since that is where it seems to come from. I have an 09 E63 with the same engine.

icat0963

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.