[infrastructure]

Hello everyone! First time posting anything here. Got really desperate with a new sound which 'appeared' on my 2012 320d just few days ago, so I'm turning to my favorite forum for help in diagnosing this problem. I have made two short videos and posted them to YT to aid you guys in diagnosing this as much as I could (links at the bottom)

Few days ago I turned on to a steep uphill road, I was in a slight gearing disadvantage at around 1400rpm, and as I had a phone in my right hand, I decided not to downshift but rather lug the engine few meters till I get into the high power/torque zone (something I do very rarely). This is when I heard it for the first time: A short clattering noise coming from the engine bay(seems so to me at least), lasting for not longer than 150 to 250 rpms. If I had to describe the sound/frequency I would compare it with a small coin/penny sitting inside a vibrating metal container (made from some thin alu. alloy, much like those generic kitchen bowls everyone has sitting around).

I was trying to reproduce the sound for the next 2 days, and could only hear it in the following scenario(video 1): Putting the engine under medium load (30-60% opened throttle) at ~1500 RPM (car is on the move ofc). Turbo starts to spool up, the revs start going up slowly and at about 1750rpm the sound starts and lasts for about 150rpms give or take. It seemed I could not reproduce it by opening the throttle much less or much more than that, and I also couldn't hear it when revving the car stationary. Really seemed to only happen in the above mentioned throttle opening range. Also worth mentioning is that the sound doesn't happen in the rpm range above ~2100rpms, no matter the load I put the engine under!

This morning I was going to work, I start the engine in my garage and that is when I heard the sound for the first time while the car was not on the move! In this scenario(Video 2) I would pat the gas pedal with my toes, touching it very gently, just enough to see the movement of the tacho-needle. I was also able to get it to rattle consistently at certain RPMs, just above idle!

My first thoughts were maybe a loose heat shield or something in the exhaust, however I couldn't suppress the sound by putting pressure with my hands on anything within my reach in the engine bay. Sounds like its coming from under the engine... Any educated guess would be of an immense help to me right now, as it is really starting to bother me, especially since I feel the sound is becoming more and more frequent. Thank You all in advance!

Video1:

Video2:

Update: Was testing the turbo again today, driving on a steep hill in a high gear, throttle wide open, haven't heard any concerning noise coming from the charger itself (no blows, whistles, howls...)

[andreigbs]

I'd hate to say turbo, but it's quite possible.

[Enabled]

It almost sounds like something loose under the car. If you haven't visually inspected underneath, I'd start there.

[infrastructure]

Originally Posted by andreigbs

I'd hate to say turbo, but it's quite possible.

I really think its not the turbo. I dont hear it when lifting off the gas pedal, also I cannot reproduce the sound through the whole rev range, occuring only at very specific vibration frequency/ rpms. Also my turbo never gave me any other signs of damage: no smoke, no weird noises... Only thing it could be on the turbo is the wastegate actuator, but then again, I should hear it while cruising and then lifting the pedal shouldnt I?

[infrastructure]

Originally Posted by Enabled

It almost sounds like something loose under the car. If you haven't visually inspected underneath, I'd start there.

Hmmm, what would you look for?