[Krisp97]

***RESOLVED as of 3/18/24: Here is a video of the noise at cold start. In my case, the culprit was the Deflection Pulley aka Idler Pulley: https://www.youtube.com/shorts/7L_otqh_Bxk

I have found little information regarding this sound with my G80 M3 on cold start in low temperatures. I noticed when in the low 30 degree F and below, the car squeals/whistles for a few moments, sometimes a few minutes if very cold.

Initially thought its probably a belt or pulley, took my car to BMW and they said it was due to aftermarket intakes. I knew this wasnt the case, reverted back to stock: same sound persisted. Not related to intakes at all.

Car is back at BMW a second time now since 01/10/2023. They have replicated and identified the sound, thinking it was a pulley or belt sound. They replaced the belt, retested, and today said the noise persists. I miss my car!

They are opening a case with BMW NA and going to record audio clips to submit with the claim. I am frustrated I haven't had the car long and now this happens, but my dealership has been very determined and eager to sort this out.

I will continue to post updates as I get them. I also posted some in the older thread about G82 M4 Cold Start Noises. I started a new thread in light of helping others that seem to have this mysterious noise that is not documented hardly anywhere.

[Info@mad-us.com]

Could be a pulley bearing or belt. Does it increase with engine rpm?

[2022m3x]

Hope this gets sorted out! Thanks for the update. I’ve been experiencing the same but just didn’t bring it in..

[Krisp97]

Originally Posted by Info@mad-us.com

Could be a pulley bearing or belt. Does it increase with engine rpm?

Yes, when the sound occurs for more than a couple seconds, it will do it relative with RPM up to about 1800 or so then stops until RPM's drop lower. I have said all along I believe it is a pulley or bearing of some nature based on this. Belt was replaced which I figured would not fix anything, but understand they have to go through the process. I work in the car business too so I get it! Will see next week if we get any updates.

[Krisp97]

Originally Posted by 2022m3x

Hope this gets sorted out! Thanks for the update. I’ve been experiencing the same but just didn’t bring it in..

Definitely bring it in ASAP to see if they can replicate it and get it diag'd. Sounds like I am one of the first (atleast on here) that has taken it in to get sorted.

Could be something that results in a TSB if enough issues are reported

[Info@mad-us.com]

Originally Posted by Krisp97

Yes, when the sound occurs for more than a couple seconds, it will do it relative with RPM up to about 1800 or so then stops until RPM's drop lower. I have said all along I believe it is a pulley or bearing of some nature based on this. Belt was replaced which I figured would not fix anything, but understand they have to go through the process. I work in the car business too so I get it! Will see next week if we get any updates.

I won't say it's easy to find the noise but it's fairly easy to rule out a noise on a pulley with the right tool.

Without a video or sound clip it's tough to guess where it's coming from. Valve covers make a whistle or high pitch hiss and a belt or bearing can be a grind to a constant chirp with time between.

[Krisp97]

Originally Posted by Info@mad-us.com

I won't say it's easy to find the noise but it's fairly easy to rule out a noise on a pulley with the right tool.

Without a video or sound clip it's tough to guess where it's coming from. Valve covers make a whistle or high pitch hiss and a belt or bearing can be a grind to a constant chirp with time between.

I provided them a video of the sound and they replicated it as well. Their team lead is on it now, case being opened for warranty, I would be surprised if they didn’t test the pulleys while they had the belt off, but who knows.

[Ximian]

My car is parked outside and on very cold days that are somewhat humid, I get a squeal on a cold start. I assumed it was somewhat normal and it's not easily reproducible for the rest of the day. Mine only lasts <15 seconds never in the summer. Do you have an example with sound?

Mine is -

[stalintc]

I have the same issue since new, assumed it was normal. How's away after about 10 seconds, when it occurs. Also parked outside in Michigan so not exactly warm all the time.

[Krisp97]

Originally Posted by stalintc

I have the same issue since new, assumed it was normal. How's away after about 10 seconds, when it occurs. Also parked outside in Michigan so not exactly warm all the time.

Exactly whats been going on for me. The sound would go away before they could pinpoint exactly what it is. When we had a really low cold snap few weeks ago, this noise lasted for a few minutes. Hasn't been lasting that long since, only really starts doing the noise in the mid-low thirties Farenheit and under.

[Krisp97]

Originally Posted by Ximian

My car is parked outside and on very cold days that are somewhat humid, I get a squeal on a cold start. I assumed it was somewhat normal and it's not easily reproducible for the rest of the day. Mine only lasts <15 seconds never in the summer. Do you have an example with sound?

Mine is -

It is essentially that exact sound. I have a video on my iphone but cant figure out how to post here lol. But that is it. Not normal -- I suggest taking it in! Something is not right with these

[Ximian]

Originally Posted by Krisp97

It is essentially that exact sound. I have a video on my iphone but cant figure out how to post here lol. But that is it. Not normal -- I suggest taking it in! Something is not right with these

Mine isn't easily reproducible. It would have to sit at the dealer overnight when it's very cold and even if it does happen, it lasts a few seconds.

If it's happening for you more easily and frequently, then we're all relying on your dealer and car to figure out the cause.

[Krisp97]

Originally Posted by Ximian

Mine isn't easily reproducible. It would have to sit at the dealer overnight when it's very cold and even if it does happen, it lasts a few seconds.

If it's happening for you more easily and frequently, then we're all relying on your dealer and car to figure out the cause.

Yes mine has to sit overnight too, my dealer was going out once per morning around 7:30am when cold out to try to replicate it. Finally got it a few times. I will definitely post up the results of the case with BMW NA. They are going to snag a audio clip of it this week to see how to proceed with the claim.

[stalintc]

Here is a video of mine from Jan 2022. I think it happens 5-10 times per year.

https://youtube.com/shorts/6F6X5FP10Y4?feature=share

[Krisp97]

Originally Posted by stalintc

Here is a video of mine from Jan 2022. I think it happens 5-10 times per year.

https://youtube.com/shorts/6F6X5FP10Y4?feature=share

That is the sound I am experiencing as well. Not sure what is causing this but eager to find out. I really don't know of anyone else that has taken their car in to have this diagnosed other than myself. Seems like most are pawning it off as "normal" but it is definitely not

[Krisp97]

They have submitted over audio recording to engineering, hoping to get a bit longer of a recording in the next few days. My advisor said it will be a slow process and that he will keep me updated. Missing that car more than ever!

[Krisp97]

Update: BMW Engineering has asked them to remove the belt, identify the "index number" on the belt tensioner, and start the vehicle when cold to see if noise persists. I am guessing this is to verify if it is actually a pulley as opposed to something with the motor, which I am almost certain its the tensioner.

They said they are parking my car inside for the pending bad snowstorm coming tomorrow, I appreciate them looking out for me

Hoping to hear something by the end of the week!

[Krisp97]

Car was started a few times in the cold without the belt on, no noise. This pretty much narrows it down to something within the pulley system. Waiting to hear back from the dealership at this time, they are awaiting further instruction from BMW Engineering on what to do next. We are getting closer!

I am hoping to have my car back within a week or so if that doesn't seem too unreasonable

[Krisp97]

***UPDATE: This did not fix it. I am in contact with my dealership again as of 3/2/24, I am thinking a different pulley is to blame. They ended up replacing the Idler/Deflection pulley which remedied the issue!***

Original post: I would like to excitedly report that I have just got the car back after 3 and a half weeks. After alot of "test-and-wait, then test again", it is now fixed.

After first replacing the drive belt itself to no avail, BMW Engineering instructed them to remove and replace the belt tensioner and re-test. Luckily the weather has been cold enough for testing. They tested it over the span of three days and it no longer is making the sound.

It was the belt tensioner all along like I had anticipated! Anyone with this sound, I encourage you to take it in -- its NOT normal like some have thought. They mentioned there is currently no service bulletin for this issue. Get your cars fixed up and this issue more known!

Part number used was 11-28-8-580-360 for the Belt Tensioner. A $150 part.

[J_Supplanter]

Thank you for the detailed journey of fixing this issue! A model contribution to the community. And congrats on the success!

[Krisp97]

Drove it today aaaand heard the sound when I went out to start it Not sure what to do at this point. I may reach out to the dealership again. Only issue currently is that it's currently a bit warmer out and harder to replicate.

I feel stuck and really thought they got it this time. I am sure they would love to hear from me again

Anyone else taken theirs in yet?

[BIGW0RM]

I dont hear that squeel sound. But I hear a distinct "ratchet" like sound when mine cold starts. Its like a gear sound for a split second. Closest sounding thing I can think of would be a ratchet cranking sound.