star221

New member here. Thanks admin for the approval!

​​​​​​I Have a 2007 S550 4matic. With 101k kms.
Just last week i had this whining/ whistling noise coming from behind the engine.
it is rpm related. It gets louder when i step on the accelerator pedal. And the sound stays there all the time, Park, Reverse, Neutral, Drive, and even on idling or car is in motion, the sound doesn't go away.

We pulled the serpentine belt to see if it's one of the pulleys are making the noise. But the whining noise are still there. So means all my pulleys and belt are good. Also the secondary air pump is good.

I was thinking it could be the transmission, torque converter or transmission oil pump failure. Fluid is full when we checked. and no leaks. And the car shifts smooth and fine, no jerks, no slips. And it shifts on point.

IF the issue is transmission, the car should not shift as normal am i right? after reading all the topics, all of them has issue with shifting and delays and jerking. But mine doesn't have any of those. I don't wanna spend $3k for a transmission rebuild and ended up the issue not solved. Could this be something else? Thanks for all the inputs!

Here is the youtube link to the same sound i'm having. Except the video is s63, and mine is s550? But it the exact same sound.
https://youtu.be/vhACDRbSjiw
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Senecat

The uploader of that video stated in the comments that the sound was resolved with new engine mounts, so I'd start there.

Senecat

Well looky there, he even stated it in the video description. I just noticed.

Looks like it's time for mounts. Let us know how it goes.

star221

yea i've read that comment too. but how could an engine mount make that whining sound? that's pretty weird. and i checked all my mounts and my mechanic they are all thight and no play at all. i went to 2 independent mechanic already and first one said it's the cam lobes. but the engine runs fine, no misfires, no check engine light and runs smooth. and they are really not 100% sure. second mechanic said it's coming from the transmission but it runs and shift perfect. i'm so confused... don't wanna keep throwing money at it and problem hasn't been resolved.

on a side note: anyone from toronto here that could help me diagnose this issue? i'm willing to pay the diagnostic fee. or any mercedes mechanic recommendation in toronto? thanks

BOTUS

if you hear a whine inside the car that seems to be the gearbox and it changes when using the S or C switch, turn off the AC if it stops the condenser has probably rotted through and its low on AC gas

normal failure mode on modern cars - Porsche intercoolers and air condensers are lucky to reach 3 years, Mercs of this vintage do 9 years

Senecat

I would think there would be AC related faults if the system charge was that low. These cars use clutchless, variable-displacement compressors that are always circulating. If the leak was that bad, AC wouldn't blow cold at all and DTC's would trip.

BOTUS

no just the noise