[edgarchieng]

Originally Posted by Max Well

Quite a mystery, edgarchieng, and can understand your frustration over this perplexing noise issue. Just a few questions and thoughts as your recent videos were quite illustrative-

1. by saying they used an 8 channel mic, does that mean one that localizes the sound in space? If so, was that not able to refine the potential source area any better, which could certainly provide a more focused analysis of possible causes?

2. and was the mic able to record waveform and frequency for further analysis or just dB and attempt at localizing?

Performing a GoogleSearch there appears to be rather inexpensive waveform audio software out there (one example was at https://www.nch.com.au/wavepad/fft.html , WavePad FFT Sound Analyzer (Powerful Audio Analysis Software) ), but I have zero background in this area so have no idea if it would be able to assist you in characterizing the sound, or whether that would even help to narrow down causes.

Another thought might be to see if someone at Univ Adelaide's Mechanical Engineering Dept would be curious enough to solve the mystery of at least what type of sound it might be. There appears to be an Emeritus Professor in their Department who has written extensively on sound analysis, and perhaps he (or his office) could at least point you and your Svc team in the right direction as to how to pinpoint and analyze it? https://www.who.int/occupational_hea...ons/noise1.pdf Emeritus Professor Colin H Hanson, Dept of Mechanical Engineering, Univ Adelaide

It sounds to me like the sound of an intermittent pressure-valve type release of air or gas, almost as if one had an air-filled balloon held closed with both hands using your index fingers and thumbs, and if you quickly pulled your hands apart briefly you could produce a similar impulse of sound? I just don't have enough automotive engineering knowledge to even guess what type of pressured air/gas systems would even be able to produce such a sound, if indeed that hypothesis is correct.

Certainly an interesting issue and hope you will keep us posted.

Thanks for the referral will definitely try and reach out to them.

As for the "chassis ear" they've used, yes it does exactly as what you've described, the aim to try and localised where the noise is coming from.

But it's been quite challenging for them obviously as there are a variety of other noise such as mechanical and road noise around but they have traced it to the rear of the car on passenger side (or driver side for America) but my experience and gut tells me it's coming from the front.

However it's definitely not coming from any parts within sights or easy reach, it's coming from deeper inside the parts.

And yes it does sound like a gas or compressed air leaking sound but what baffles me is how controlled the sound is in terms of length of the sound at whatever speed I'm driving (the noise volume is variable though)

All I can say right now is this is definitely isolated to the M40i Australian delivered variant only.

[shinyred]

my 40i has this "glonk"-kind of sound coming from the rear section of the car while the same driving conditions, very often when braking while slow speeds in the carpark. I suspect its likely the transmission change (low gear to stopping) and exhaust, or possibly brakes, suspension. Sounds like that from since i collected the car in Dec, driven 1000 mi so far.

[edgarchieng]

Originally Posted by shinyred

my 40i has this "glonk"-kind of sound coming from the rear section of the car while the same driving conditions, very often when braking while slow speeds in the carpark. I suspect its likely the transmission change (low gear to stopping) and exhaust, or possibly brakes, suspension. Sounds like that from since i collected the car in Dec, driven 1000 mi so far.

Does it sound the same like my video? Otherwise the glonk or clank sound might come from the ABS system which is quite normal

[shinyred]

Originally Posted by edgarchieng

Does it sound the same like my video? Otherwise the glonk or clank sound might come from the ABS system which is quite normal

i never heard that little squawk whine/squeak as your m40i. mine's most likely the abs "glonk"

[Makila2a]

Hey Edgar

I've got the same sound occurring as you do, not as often at the moment, but it's the same sound. I've only done a few thousand miles in UK M40i, and I started noticing it when the weather here got colder (below zero celsius). There doesn't appear to be a pattern to it at the moment, it happens every so often, usually on straight bits of road, bumpy or smooth, it doesn't go in time with suspension movements.

It's definitely coming from the rear of the car for me.

I just put it down to the cold, until I stumbled on your thread. I'll need to give it some more attention.

Are you any closer to a fix?

[edgarchieng]

Originally Posted by Makila2a

Hey Edgar

I've got the same sound occurring as you do, not as often at the moment, but it's the same sound. I've only done a few thousand miles in UK M40i, and I started noticing it when the weather here got colder (below zero celsius). There doesn't appear to be a pattern to it at the moment, it happens every so often, usually on straight bits of road, bumpy or smooth, it doesn't go in time with suspension movements.

It's definitely coming from the rear of the car for me.

I just put it down to the cold, until I stumbled on your thread. I'll need to give it some more attention.

Are you any closer to a fix?

No fix yet as I'm waiting for the car to be sent back to BMW.

Well now at least we know it's not just limited to Australian delivered M40i but clearly this is happening on RHD.

Mine is not limited to just cold temp or cold start, I could be driving for well over an hour and still get it and in my case when the weather gets warmer it's more frequent

[eraxy]

I have exactly the same noise. Mostly 2 or 3 minutes after cold start and driving on the road.

Did you find out what the issue is?

[fernandohdl]

Seems to many strange noises for such an expensive car.

Mine is a little different when I change gears and also only happens in specific situations:

And also dealer cannot find a real solution

[spangle1980]

Originally Posted by edgarchieng

Here's two better sound quality video to show you guys the noise, which until now has not been fixed nor has the source able to be identified.

The car has spent almost a third of its time in my ownership in the hands of BMW Adelaide service centre, I've escalated through to BMW Australia HQ and they just sent me back to the dealership for further investigation. This has been ongoing now for over 5 months, so if anyone has any idea what is the issue it would be really appreciated

That's pretty freaky. I had that exact same noise on my outgoing 3.5d Msport. Only difference being it happened on average once per two weeks, typically on acceleration. I initially thought it was something, upon acceleration, the kids had left in the rear storage bucket. But it was so infrequent I didn't check for a few months until I ruled that out.

To be honest, due to frequency, I couldn't be arsed to go to the pain of having a dealer take it and say they couldn't find anything so lived with.

I wish you all the best!

[edit - I am talking about the thing that sounds like a weird bird chirp]

[edgarchieng]

Originally Posted by fernandohdl

Seems to many strange noises for such an expensive car.

Mine is a little different when I change gears and also only happens in specific situations:

And also dealer cannot find a real solution

The sound is identical if not similar to mine, but I'm surprised it only happens on gear changes.

[edgarchieng]

Originally Posted by spangle1980

That's pretty freaky. I had that exact same noise on my outgoing 3.5d Msport. Only difference being it happened on average once per two weeks, typically on acceleration. I initially thought it was something, upon acceleration, the kids had left in the rear storage bucket. But it was so infrequent I didn't check for a few months until I ruled that out.

To be honest, due to frequency, I couldn't be arsed to go to the pain of having a dealer take it and say they couldn't find anything so lived with.

I wish you all the best!

[edit - I am talking about the thing that sounds like a weird bird chirp]

Yeah I'm just about given up myself. My wife doesn't know what it sounds like yet cause I haven't told her to specifically hear it out.

But once you've heard it and picked up what noise it is you can't unhear it and it becomes annoying.

[edgarchieng]

Originally Posted by eraxy

I have exactly the same noise. Mostly 2 or 3 minutes after cold start and driving on the road.

Did you find out what the issue is?

Not yet, I haven't had the chance to return the car to the dealership, we couldn't coordinate the availability since I'm constantly travelling for work

[fernandohdl]

Originally Posted by edgarchieng

The sound is identical if not similar to mine, but I'm surprised it only happens on gear changes.

Yes, only on gear changes and only if I push harder and also not everytime, and when happens, only 2-3 times per initial ride. After this, I can kick down and will not happen again.

Very very annoying and no clue to solve it.

[edgarchieng]

Latest update: BMW Adelaide apparently said it was the dust cover on the steering rack (or steering pump, one of the other) that was causing the weird noise and have since rectified it.

I don't know how and what they did but so far in the last 2 days since I've picked the car back it hasn't made the noise

[edgarchieng]

Ok so the service manager at BMW kindly rang me this morning to check if the noise was still coming up over the weekend.

I said it seems to have been gone because we've had extreme hot weather and then cooled down the following days and I have not heard the screeching/squawking noise in neither of the condition.

I asked for what exactly was the problem and they told me it was apparently a "dust cover on the front diff seal" which spins every now and then causing the noise, so what they did was to fix (or glue) it in place so it doesn't spin anymore

So for any of you out there who has this problem, this could be the answer.

[Louda0801]

Turbo waste gate or blow off valve?

[MechX3M40i]

Originally Posted by edgarchieng

Ok so the service manager at BMW kindly rang me this morning to check if the noise was still coming up over the weekend.

I said it seems to have been gone because we've had extreme hot weather and then cooled down the following days and I have not heard the screeching/squawking noise in neither of the condition.

I asked for what exactly was the problem and they told me it was apparently a "dust cover on the front diff seal" which spins every now and then causing the noise, so what they did was to fix (or glue) it in place so it doesn't spin anymore

So for any of you out there who has this problem, this could be the answer.

Great to hear that it's now resolved! it's been a long while but it's finally over

if you can post a copy of the dealer write up, that would be helpful for others whom may experience the same!

[edgarchieng]

Originally Posted by Louda0801

Turbo waste gate or blow off valve?

Nope

[eraxy]

Still fixed for you?

[eraxy]

?

[dtuohy1]

Also have 2018 X3 M40i (just hit 12 months and 15,000 kms).
Squawking noise has been there for probably 6 months - perhaps more as we just thought it was a resident bird ! I wish I could narrow the circumstances, but it seems to be not confined to hold/cold, smooth/rough, straight/turning - but every time I think I have it sorted, it again baffles me.

Reported to BMW Sydney at first service. They heard and acknowledge the problem. They checked oil in transfer case and was dirty, so replaced it and could not get it to make noise. Returned car and asked me to drive for 300kms. After a few days, the noise was back.

I then did a drive on freeway (80km/hr) in Sport mode and unlike previous single spurts of squawking, this was continuous for 10-15 seconds. And since I was driving alongside a concrete barrier, the noise was bouncing back and very annoying and embarrassing. So returned the car to BMW Sydney.

It has been at BMW Sydney for 2 weeks with this 2nd visit. They continue to acknowledge sound with technician taking car home at night. They checked the dust covers mentioned on these posts (I showed posts to to them). They also spoke with BMW Adelaide where another on this or similar post had same issue and reported as solved. They h ave tried the microphones attached to car (under BMW Tech Support). Did not point to anything conclusive. Today they swapped over the drive shaft including dust covers from a donor BMW in stock (again under advice from BMW Tech Support). Still making noise. So now back to the microphone setup and hopefully more time allocated to the vehicle.

Will keep folks updated - but no closer to solution.

[X3M40i_Nev]

Originally Posted by dtuohy1

Also have 2018 X3 M40i (just hit 12 months and 15,000 kms).
Squawking noise has been there for probably 6 months - perhaps more as we just thought it was a resident bird ! I wish I could narrow the circumstances, but it seems to be not confined to hold/cold, smooth/rough, straight/turning - but every time I think I have it sorted, it again baffles me.

Reported to BMW Sydney at first service. They heard and acknowledge the problem. They checked oil in transfer case and was dirty, so replaced it and could not get it to make noise. Returned car and asked me to drive for 300kms. After a few days, the noise was back.

I then did a drive on freeway (80km/hr) in Sport mode and unlike previous single spurts of squawking, this was continuous for 10-15 seconds. And since I was driving alongside a concrete barrier, the noise was bouncing back and very annoying and embarrassing. So returned the car to BMW Sydney.

It has been at BMW Sydney for 2 weeks with this 2nd visit. They continue to acknowledge sound with technician taking car home at night. They checked the dust covers mentioned on these posts (I showed posts to to them). They also spoke with BMW Adelaide where another on this or similar post had same issue and reported as solved. They h ave tried the microphones attached to car (under BMW Tech Support). Did not point to anything conclusive. Today they swapped over the drive shaft including dust covers from a donor BMW in stock (again under advice from BMW Tech Support). Still making noise. So now back to the microphone setup and hopefully more time allocated to the vehicle.

Will keep folks updated - but no closer to solution.

Oh no :-( My car is due to go in for a week on the 22nd, and based on what you are saying, won't be holding out that they will fix this. Ironically I have not heard it now for a few weeks, but the weather has been very warm in the UK where I live. For me, it does appear to be 1st thing on a cooler morning for a few mins until car is "warm"

I too will feedback and update