Name this sound

[Dug Nichols]

Also here’s an alt video that captures the sound better 

[Schnellvintage]

I would also check your air cleaner brackets.  I have heard that noise when they crack and or break.

 

[2O=00=O2]

Quote

• occurs in any gear, between 3k - 4k RPM's, but only when not accelerating hard and in cruise/sustain mode

 

I hear it right at 3800 - 4000 RPM sometimes on the way down from say 4500 RPM you can hear it starting again at 4200 - 3800 RPM. Watch the second video and watch the tach right at 3800 RPM.

Edited April 21, 2022 by 2O=00=O2

[Chris_B]

The typical noise analysis includes whether the noise is RPM, gear or speed dependent, occurs only on rough roads, etc. Any of these apply? Couldn't hear anything on your last vid.

Edited April 21, 2022 by Chris_B

['76mintgrün'02]

I've seen a lot of posts about rattles coming from the IE stainless exhaust.  Some of them discussed something coming loose inside the resonator and making noise at certain rpms.

 

https://www.bmw2002faq.com/search/?q=ie resonator rattle&quick=1 

 

Tom

[gracer]

OK,  I heard it this time.  I always look at what I worked on last as the problem area.  

I would say that the noise is exhaust related.  G

[TobyB]

I had a distributor with worn stops once that made an ABSURDLY loud noise for what it was...

 

But I agree- I'd be looking at the exhaust pretty carefully,

and also trying the same thing in 3rd to see if I could get the noise

to repeat.  

 

t

 

[Mikesmalaga72]

It sounds like the exhaust bracket assembly. The Rube Goldberg set up that requires affixing without tension. It appears to be an area that requires frequent visits since BMW does not specify lock nuts and due to the NVH are subject to loosening. As per the BMW blue book. Let us know thanks!

[Dug Nichols]

So I inspected the heat shield and it is on solid. Same noise happens in every gear, at the same RPM range around 3700 - 4000. Doesn’t appear when passing through that range quickly, only when moving through slowly or sitting at. Driving 65 in 4th it’s super noticeable. Accelerate to 74 and it’s gone.

 

Yep exhaust inspection makes sense. It’s just super weird how it’s so rpm specific..

[Dudeland]

My first thought was exhaust related, like something that came loose in the resonator or muffler. 

It from the "PSST" sound it is a turbo, so perhaps check for loose nuts or cracks around the collector going into the turbo, they like to crack there if the turbo is not properly supported.  Heat shields, and expansion couplers like to break as they get heat cycled and fatigued. 

 

It sounds like it is in your cabin, so check things like your linkage to your throttle, and brake lever. Check the tension on your parking brake cable, the crossover bar may rattle against the parking brake handle if there isn't enough tension. 

[stone02]

if the car has the original exhaust bracket at the back of the trans then I would check the "U"

clamp that holds the pipe to the long arm and then check the long arm to small bracket

rubber bushings. sounds like the pipe "U" clamp to me.

stone