[Burnside81]

Hello all,

I’ve got a new M2c and when accelerating from low revs I get a rattle at around 1800rpm that stops by 2000rpm. It sounds exhaust heat shield like to me.
It will obviously go back as a warranty thing but just wondered if anyone else has experienced similar? I’d rather point the dealer in the right direction than have them poking around my car for too long!

My car is a UK, RHD manual. Currently on 296 miles.

TIA!

[MR RIZK]

Yeah I think I hear it also. Faint but it is there somewhere. Also RHD MT

Keep us in the loop

[j23]

Is the car stock? 2021?

[NISFAN]

The exhausts are super tightly packaged. I bet a heat shield screw or something is touching the exhaust as it vibrates in that frequency zone.

[Burnside81]

Originally Posted by j23

Is the car stock? 2021?

Yes it is. Fully stock.

[Burnside81]

Originally Posted by MR RIZK

Yeah I think I hear it also. Faint but it is there somewhere. Also RHD MT

Keep us in the loop

I’ve had no luck tracking down this noise. Have you found anything?

[MR RIZK]

Originally Posted by Burnside81

I've had no luck tracking down this noise. Have you found anything?

Haven't tried to be honest. I suspect it is either the exhaust valves or a little bit of waste gate rattle. Hard to pin point the source location.

[m2cWW]

Originally Posted by MR RIZK

Haven't tried to be honest. I suspect it is either the exhaust valves or a little bit of waste gate rattle. Hard to pin point the source location.

Might be a stretch, but that noise got louder for me when I changed my exhaust. Turned out it was the rear view mirror housing rattling. When you get to around 1800, try to squeeze the housing right behind the rear view mirror (big black piece split down the center) and see if that helps. Sorry if it was just on mine, and good luck!!

[Burnside81]

Originally Posted by m2cWW

Might be a stretch, but that noise got louder for me when I changed my exhaust. Turned out it was the rear view mirror housing rattling. When you get to around 1800, try to squeeze the housing right behind the rear view mirror (big black piece split down the center) and see if that helps. Sorry if it was just on mine, and good luck!!

Thanks for that. I'll check it out. Although I can only hear it with the window down so it's doubtful but you never know!

[m2comp_sb]

Resurrecting this post! Did anyone discover what was causing the 1800 rattle?
Mine has exactly the same, and I assumed my aftermarket Milltek exhaust was the cause, but having spent a lot of time with an exhaust fabricator last week, inspecting and testing, we can see nothing obvious relating to the exhaust. Seeing as people report hearing this noise on a stock car, assume it's something else. Can anyone shed light?

[maxcbrdriver]

I've got a completely stock 21 and I do hear a slight rattle just below 2k rpm on acceleration. I haven't and likely never will investigate it as it's not that big of annoyance.

[rogeroger]

I had this while driving at lower rpm but also at cold start. My car is stock, under 3000 miles. I took it into the dealership and they determined that it was the exhaust muffler. They've ordered a new for replacement 👍

[fanofbmwe46]

Could be the wastegate rattle if it's around 1600-1800 rpm

[Maynard]

I get this noise - 2021 DCT w/ no mods. Mostly is is during city driving, moderate throttle. I'm not keen to have the dealer start pulling stuff in a random attempt at a fix, more worried that it was s/t working its way loose. Knowing it is more common helps reassure on that.

[m2comp_sb]

As Maynard says above, it's kind or reassuring to know many are experiencing this with un-modified cars, although I am still curious as to whether it is exhaust valve or turbo waste gate related as would be nice to see if a fix is possible.

[Bad Noodle]

New here and am having the same issue. Very subtle rattle between 1500 and 2000 rpm on light throttle. Sounds like a heat shield but I’ve tapped and checked every piece. Tapped all over the exhaust and just can’t replicate it. Took off the belly pan and oil cooler plate and found nothing. Running out of ideas. Anyone figure this out?

Stock DCT

Thanks
-BN

[Bad Noodle]

Update: Got a steelman rattle finder of amazon and found the noise is coming from the exhaust. Not sure where exactly, but placing a clamp on the down pipe connection reproduced the rattle in the microphone. Placing the clamp on heat shields and other components did not.

image for reference:

[Bad Noodle]

Another update: found a similar post -

https://f80.bimmerpost.com/forums/sh...1657374&page=4

Was able to hit the up/midpipe connection with the palm of my hand and reproduce the rattle. Had to hit it much harder than I thought. Bought the outline parts to replace at the connection and will report back.

[Bad Noodle]

Started working on the fix and found the following:



The driver's side pipe was about 6mm longer than the passenger's and looked like it could be knocking the inside of the midpipe. So I got out the dremel.







Looked great. I put everything together and .... the rattle go louder...

[Bad Noodle]

After much cursing, some beer, then more cursing, I finally found the problem:



For some reason one of the mesh washers on my downpipe hanger was missing causing the bolt to jiggle and rattle. Threw some washers in to fill the space and done. Rattle is gone. Victory. Only took 2 months to track this down.