2011 W204 C220 CDI - Whine (Turbo?!)

[Ktayl10]

Hi all,

My beloved MB with 68k miles on the clock from new is whining (sounds like a cat whining and is more prominent the harder I push the car).

I have removed the missus from the car and the whining is still there before anyone asks :-

Two MB indy’s have looked at it and can’t pinpoint the problem but can hear the noise.

They have confirmed noise is still there with serpentine belt removed, there are no boost leaks, exhaust manifold gasket is fine, no visible turbo leaks or smoking, disabling the turbo boost stops the noise, which can otherwise can be heard from hot or cold, at about 1800rpm. One indy said they think it’s the turbo but couldn’t confirm, my other indy (my go to and highly respected indy, both in mine and many others books) said they were able to stop the noise when disabling the boost but don’t honestly believe its a turbo issue.

I’ve had her since her first MOT and she’s had full service history (MB and MB indy), auto gearbox service at 46k miles.

Anyone come across something similar or maybe know a turbo specialist I could take the car to, preferably south.

Thank you kindly for any advice or suggestions.

 

[Ktayl10]

Can anyone help with the above query?
Thank you

 

[oigle]

My 2003 ML270 diesel used to whistle a bit when cold under light acceleration but went silent when warmed up. Never caused any issues. Not sure if oil viscosity was the determining factor. Unless too annoying, I'd ignore it. If it gets worse, be more easily found. Good if better or stays same.

 

[mersum1es]

yep, mine W210 was like oigle's, It leaked from intake manifold. In addition fact that OP's OM651 intake manifld bolts are prone to loose, I would suggest doublecheck that again. Did your indy smoke test for boost leak?

 

[Ktayl10]

I’ve no idea what the test was for boost leak. Was hoping to accumulate some ideas on the forum and take those back for further investigation. I’m hoping to buy a C300 coupe but the whining on mine would put anyone off of buying/PX’ing it no doubt

 

[oigle]

Sounds like it must be bad. Wonder if turbo has accumulated some buildup on vanes or could vanes be damaged? Think I would take it off and have it inspected if it is as annoying as you say.

 

[Ktayl10]

Yes that whine gets to you, really does sound like a cat crying under the bonnet.
Worst case maybe I’ll soundproof the car!