[Rob_G77]

This 'rattle' sound comes from the pulley area of my 2021 M340I. For reference, my 2020 Z4 has never made this noise. Does anyone know what this is?

Rob

[bimmerMytlas]

Mine is kind of doing the same... I think that just normal, to be honest you should try to stop trying to hear something from the engine bay. I once was like 2 hours in front of my car hearing all kind of sounds and centra coming from my car and I was like "its broken".
Those are brand new cars, just drive them and enjoy them. If there is a problem just go to dealer to fix it

[Cabrio Luv]

Originally Posted by Rob_G77

This 'rattle' sound comes from the pulley area of my 2021 M340I. For reference, my 2020 Z4 has never made this noise. Does anyone know what this is?

Rob

Heh Rob
2 months ago, my 2021 G22 was only a month old with 1000km on the odo, when I experienced a Check Control - Power Supply warning while out on a drive. iDrive message asked that I stop and do not continue driving. Since I was on a busy 2 lane highway, I continued on until I could find a safe location to do so. Throughout the remaining 20 minutes of drive, the warning cycled on and off while I switched between Drive Modes. On Eco Pro, it would stay off. After I've stopped, I powered down completely, locked the car and re-started 10 minutes later. No more warning appeared and I drove home an hour away with no further incident.
Sent the shop foreman an email detailing the above and he asked that I bring the car by the next day to have them check it our thoroughly.

To make a long story short, the car ended up in their shop for a week and half. After much back and forth between the dealership and BMW Canada and BMWNA, they ended up changing the following components, one of which was because the foreman insisted due to a noise that he detected coming from the pulley and/or alternator:
- ribbed Vee Belt
- charge air induction
- mechanical belt tensioner
- RP alternator
- vibration damper
- another ribber Vee belt
- shaft seal

Go figure, Rob!

[AZHusky]

I too am hearing this noise. It goes away when I put my hand on the tensioner. Did anything come of your sound or you just ignored it?

Video of my engine making similar sound.

https://pixeldrain.com/u/XVLmyTaA

[M340I///M]

I had a similar experience when I bought a brand new 2017 Type R , 100 miles on the odo. And the turbo malfunction, the sensor that is connected to the engine was short ( a flawed design) when the engine shifted it pulled the wires right out the plug. Causing the turbo malfunction. The car advertised me to pull over , I did. Had I not my engine would have suffered.

If your under warranty and even if your not , take it to get checked doesn’t hurt. I rather spend 120 bucks on a diagnostic than getting hit with a huge repair bill because I decided to try and out smart the cars ecu warnings.


New cars fail all the time. It’s more common then you think.

[drwankel]

I had this same rattle, and it was a belt tensioner. Replaced at the dealer under warranty.

[AZHusky]

Originally Posted by drwankel

I had this same rattle, and it was a belt tensioner. Replaced at the dealer under warranty.

Did you replace right away? Was it something that was more of a nuisance or actual signs of failure?

[drwankel]

Originally Posted by AZHusky

Did you replace right away? Was it something that was more of a nuisance or actual signs of failure?

Slight backstory. Car is new to me, I am the second owner. A couple of weeks after getting the car, I compiled a list of warranty items that needed to be addressed and sent the car off to the dealer. Tensioner noise was one of the items.

No idea how long the tensioner was making that noise before I got the car.

As far as it being a nuance or sign of failure, you can look at it two ways. The tensioner shouldn't be making noise at all, so it's technically already failed. Alternatively, it's entirely possible it's the start of something that eventually leads up to catastrophic failure of the part.

With the car under warranty, there's absolutely no reason to not just go get it immediately fixed.