Strange whistle/whine

[Lpitt]

Hi thanks for the add, I have a 2014 cla45 amd have this strange noise. Anybody else had this or know what it could be? Its only quiet but it's annoying!!

 

[Lpitt]

Still struggling to locate this noise if anyone can help at all?

 

[AMGeed]

Do you have a local MB specialist who could take a look?
Main dealers will want an arm and leg to diagnose.

I always suspect hoses being the source of whistles/whines on a turbocharged car.

 

[Srdl]

I’m not technical at all but it sounds like a turbo whistle to me. Perhaps some “experts” will be along to confirm or suggest an alternative.

Where do you live, someone may know a decent Mercedes Indie near you.

 

[John Laidlaw]

Boost valve possibly? Sounds like the whine you hear from inside a BTCC car or rally car when the compressor is spoiling up- as others it needs a specialist to have a look see- although depending on how loud it is it might be normal- has it always been like this?

 

[Lpitt]

Thank you for the replies everyone. I have taken it to a German car specialist to have the crank shaft seal replaced due to the chirping sound it was making, he had a look and couldn't find the source of this whistling sound, I've got it booked in to go stage 2 on Friday, they said they will take a look as well. I've seen the same noise on other forums but annoyingly there isn't a definitive conclusion at all. They shall check for boost leaks etc on the day of tuning so hopefully it will get found then and be something simple!! I'll post an update if it gets sorted just incase anyone else has this noise in the future.

 

[John Laidlaw]

Thank you for the replies everyone. I have taken it to a German car specialist to have the crank shaft seal replaced due to the chirping sound it was making, he had a look and couldn't find the source of this whistling sound, I've got it booked in to go stage 2 on Friday, they said they will take a look as well. I've seen the same noise on other forums but annoyingly there isn't a definitive conclusion at all. They shall check for boost leaks etc on the day of tuning so hopefully it will get found then and be something simple!! I'll post an update if it gets sorted just incase anyone else has this noise in the future.

Has it had a stage 1 already ?

 

[Lpitt]

Has it had a stage 1 already ?

No stock at the moment, all bar an induction kit.

 

[John Laidlaw]

Bet your induction kit has added to the sound track...
Any tangible benefit or just placebo?

 

[Lpitt]

I can honestly say it actually made a difference, it was noticeably quicker. I've never had it before on any other car I've had but for some reason I could definitely feel a difference. I'm not talking night and day difference but definitely noticeable. Sounds great too.

 

[Petrol-Head]

Bet your induction kit has added to the sound track...
Any tangible benefit or just placebo?

I think John might be right about the sound track.

 

[Lpitt]

The noise was there before I fit the induction. Its not loud, I can't hear it with the windows up, it could be normal maybe I hope!!

 

[John Laidlaw]

The noise was there before I fit the induction. Its not loud, I can't hear it with the windows up, it could be normal maybe I hope!!

I'm tending to think it's just normal turbo spooling, but your tuning guy will know when he hears it 'in the flesh'

 

[Lpitt]

As promised an update after today, the tuner had a good look and couldn't find anything alarming causing the noise and said it could be something silly but its not affecting the car in any way. They ram a health check and stock dyno and everything was running very well and said I had a very healthy car. Stage 2 has completely transformed the car beyond my usually high and hard to please expectations. The car goes like a rocket now and I'm extremely pleased with the work est has done to it!!!

 

[Blobcat]

As promised an update after today, the tuner had a good look and couldn't find anything alarming causing the noise and said it could be something silly but its not affecting the car in any way. They ram a health check and stock dyno and everything was running very well and said I had a very healthy car. Stage 2 has completely transformed the car beyond my usually high and hard to please expectations. The car goes like a rocket now and I'm extremely pleased with the work est has done to it!!!

Any dyno graphs?

 

[Janchee]

Hi thanks for the add, I have a 2014 cla45 amd have this strange noise. Anybody else had this or know what it could be? Its only quiet but it's annoying!!

The only way you’d be able to find out what the noise is by acoustic diagnostics. I did my thesis in utilising acoustics and machine learning to predict faulty bearings way before they happened. There’s a huge market for software to diagnose faulty sounds ie replicate a 30 year experienced engineer that listens and says yeah it’s this haha.

You can download many apps that do the Discrete Fourier Transformation (DFT) on a recording device which will give you the frequency you’re hearing. Note you will have to record with the engine at constant revs

Once you do the DFT on the sound, it will give you an amplitude. Basically use hot/cold method to find the largest audio amplitude and you might be able to find the fault.

Out of interest, it was these Products that I’ve used. They’re video acoustic diagnostics by Siemens and most of the major car companies use them in testing (to find rattles etc.) Its an amazing bit of kit.

Using acoustic diagnostics, I could tell you what blade set was faulty in a gas turbine with over 400 blades. It is amazing how far its come with the power of computing. Technology has been important as you have to record at double the frequency you diagnose, so for example a normal CD rate is 44.1kHz. That is 44100 data points per second ... a LOT of data...

 

[SL63 Mark]

It made my cat freak out when I played the video.

Your ears work in stereo, and are very good at direction finding. So if you put your head under the bonnet and listen as you rev the engine, then turn your head slightly as you listen, you should be able to pinpoint the area the sound is coming from, and home in from there by process of elimination. Worth a try, and it doesn't cost anything.