CLK 270CDI 2004 Whoosing or Sucking sound?

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New Member
Jul 3, 2017
2004 CLK C270 CDI W209
Hi all

New kid on the block so bear with me.

Noticed last night that when I power on above 2500rpm I can hear a loud whooshing or sucking noise coming from what sounds like behind the glove box.

It doesn't make the noise when static and revved only when driving.

Could this be a leaky hose/pipe or could it be a poorly turbo??

Car still drives normal with no management lights on or loss of power.

Only 3 things changed in last week but doubt any of these are related.

1. I've just replaced drop links, track rod ends and upper and lower front arms
2. Replaced cabin filter, this does sound like the area where the noise it but surely unrelated?
3. Had new stainless exhaust and back box fitted from CAT back.

Car very tidy and only done 80k FSH with less than 10k in last couple of years

A bit peeved if Im honest as felt like Ivwas sat on a gem........still might be if hopefully it's something simple.

Thats where you guys, the real experts come in as my first Merc and only had it 3mths.


Sounds like a split or leaking turbo boost hose Steve.
Do you get black smoke when you put your foot down?

Check the cabin filter is seated properly too.
Check the cabin filter, seems the most likely culprit, is it correctly fitted and was it an original MB or a cheap copy, might be thinner and sound coming through when driving. Try checking that out first then if everything looks / sounds ok then look elsewhere . Am sure you will get more experienced owners giving you more info regarding possible culprits.
Hey guys thanks to all thats responded thus far, all opinions are valued and much appreciated.
I checked the cabin filter earlier and seemed ok, it was Wix one from my local Bullseye and was very similar to the one I took out.
I'm hoping it is that as easy fix and at least nothing to lose sleep over.
That said I cant understand why it only happens when I bang my foot down. If I build speed up gradually it doesn't do it even if I get up to 50-60+.
Haven't noticably seen any smoke when giving it some pasty although I have noticed sooty deposits in my new tail pipes??

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It sounds very much like a boost leak. As when giving it the beans the turbo will be on full boost and pumping max pressure through the pipework. If possible check over the rubber hoses in and out of the intercooler for splits. You will have to run your hand around the pipes and hopefully with a bit of pushing and squeezing, the hole will be apparent. (ooo err). It normally gives you black smoke and a possible lack of pwer, but if the hole is only small, it will just make a lot of noise and not a lot else!
Thanks mate guess Im treasure hunting this weekend then......oh joy.
You watch it'll in the worst possible place...I'm lucky like that!!
Thanks again will update when I know more.

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Hi Guys the time has come....or at least a cheeky hour whilst the wifes nipped out.
Right, if I'm honest Im not entirely sure which pipes I should zone in on.
I've whipped the covers off and started top RH to the left of the cabin filter box where the actual noise seems most apparent. Theres approx 5 small hoses that look to go in and around what looks like a diesel filter, problem is they all have braided covers so cant see squat. Checked what I can see all round and bent, wiggled whilst my lad revved her but no noise and no sucking sound, but then not under load so didnt expect to hear much that way.
Had air box off and oil breather pipe down near turbo and all looks ok there, is the fat lower pipe that goes groundwards the fabled intercooler pipe? It looks like it goes behind front bumper, could this be a culprit and am I right in guessing its a bumper off jobby to get to check it right??
Tempted to just bob to local garage before do that. HELP!


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PS anyone with any pics of what to check would be top drawer....wink wink

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Pic 1 is where the noise seems to be coming from.
Pics 2/3 are of the fatter hose and it does feel ever so slightly moist on the underside. Nothing to shout about and could just be crap build up but hey may just trigger something for all ye yodaz out there.

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I have w211 e270 cdi and have that same noose coming from the turbo .Like a whistle just when you start to rev .Later when revs over 3 k rpm no whistle.Car goes as it should.Maybe is the turbo orange seal.
Your noise seems to be in egr part or intake manifold has a leak.From photos.
Mines more a sucking or whooshing, to be honest first time I heard it I thought it was a box I had in the boot sliding around on the carpet.
Mine kicks in around 2-2500rpm and isn't constant.
Fingers crossed something and nothing!!

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Can say with 90% certainty it's definately coming from beind the glove box area. Had it up and down a straight road today leaning right over each time to where noise is coming from.

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Sorry for delay guys but at last good news.
Only a split boost hose!
£40 new from MD and job done.
Worth taking time to check in depth.
Hope this helps, pic of culprit attached.

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