C250 cdi turbo whistle

Simon_sen

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Hi all I have 2014 c250 cdi and I have following issue. Under load I have a turbo whistle it sounds like a siren it's not a nice sound. It comes from around 1800 revs till around 4k. Am I correct in my assumption that it has to be high boost small turbo which is causing this? I don't want to spend fortune on two new units when only one is buggered. This is second turbo which is doing then and when I was fitting it there was no play i shafts and it looked mint. Any help greatly appreciated
 

Gazwould

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As above could be alot of things , a mate had this on another car and found his compressor wheel front part of blades mullered.

2020-06-22 07.46.06.png
 
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Simon_sen

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Thanks guys, one thing which doesn't make sense is it's second turbo which makes same noise although both looked OK both had no shafts play etc. But when I went to local garage they said its turbo straight away. As that sound comes from around turbo area.
 

LostKiwi

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As suggested, check the turbo exhaust mounting flange.
 

ajlsl600

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Leading edge of impellor looks like some heavy duty dust/rubbish has been thru it. And is that a water stain or what on 3 o'clock position.
 

bembo449

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Thanks guys, one thing which doesn't make sense is it's second turbo which makes same noise although both looked OK both had no shafts play etc. But when I went to local garage they said its turbo straight away. As that sound comes from around turbo area.
Id steer clear of them then , you cant diagnose a turbo issue just by listening, all turbos whistle but how loud is down to more than just the charger itself
 
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Simon_sen

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Well what they ( garage) said is " it sounds like a turbo issue go to turbo specialists and they will tell you more" if I will now send turbo unit to them for health check its obvious they will say both turbines are buggered and will charge £600 for rebuilt. Lets be fair I am not expecting trouble shooting over web forum lol. I just thought someone experienced same issue. It's a high pitched whine from 1600 to 3000 revs
 
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Simon_sen

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£300 that would be for single turbo not two units.
Also I forgot to mention quite important info which is that whining starts after few miles. Initially everything is OK, so if Boost pipe would be damaged I bet it would whistle all the time, same thing with manifold leak but it's consistent with turbo whine.
 

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£300 that would be for single turbo not two units.
Also I forgot to mention quite important info which is that whining starts after few miles. Initially everything is OK, so if Boost pipe would be damaged I bet it would whistle all the time, same thing with manifold leak but it's consistent with turbo whine.

Manifolds and exhausts expand and change shape with heat so don't assume it would be consistent hot/cold.
 
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Simon_sen

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Absolutely, but it expands so if anything it should seal it even better also I would thing that it should leave carbon residue in leak spot? . Safe to say we can eliminate boost leak.
 

ajlsl600

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Do you have reduced power? I had a volvo A40 dump truck haunt me for a week, with a whistle and reduced power. Was an inlet manifold crack that opened up enough when warm and under manifold where there was No Access. Can't remember how many things I tried first!!
 

Kev555

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Do you have reduced power? I had a volvo A40 dump truck haunt me for a week, with a whistle and reduced power. Was an inlet manifold crack that opened up enough when warm and under manifold where there was No Access. Can't remember how many things I tried first!!
Good one to remember:D
 
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Simon_sen

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Power is there pulls very well. I will be checking for exhaust gases leaks but if it is turbo will it be the little one?
 

ajlsl600

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I believe one turbo deals with the low press side and the other the high press side so I guess? At what power do you hear the "whisleling? The sound is" under load"right.
That turbo you pictured has had some rubbish thru it. From?
 
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Simon_sen

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That picture is not a picture of my unit. That's very good question I can't wrap my head around it as you have small and large turbo. My assumption is that high press one will be small turbo and low press is the big one. So if I have a whine / whistle from 1500 revs to about 3000 then the high press small turbo must be defective as the large one would add boost at higher rpm. And yes when car is driven slowly you can't hear anything but when I put my foot down I can hear that whine. What do we think
 

Dean Fletcher

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£300 that would be for single turbo not two units.
Also I forgot to mention quite important info which is that whining starts after few miles. Initially everything is OK, so if Boost pipe would be damaged I bet it would whistle all the time, same thing with manifold leak but it's consistent with turbo whine.
My manifold had a whistle but only got worse when up to temp. Roughly 11.3 minutes after setting off :D
 
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Simon_sen

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11.3 minutes that's quite precise lol. But the whine i have is definitely on turbo side. When stationary with my foot down I can hear it there.
 

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