Wastegate rattle

[RM666]

What do you guys think of this rattle?

https://dl.dropboxusercontent.com/u/..._BMW_M6_01.mp3


My 2014 M6 F13 started doing this rattle recently.

To recreate it easily I just have to accelerate to reach 2000RPM and then let the accelerator.
That's what I'm doing on the recorded sound.
I recorded it with an iPhone on top of a box (50cm high) pointing at the passenger door at a distance of about 1 meter.

The rattle happens when the car engine is either cold or hot.

BMW first diagnose is that this rattle comes from the turbo(s) wastegate(s) and it is normal.

Doesn't sound normal to me.

[F12M6MD]

http://blog.perrinperformance.com/wp...rnalwgopen.jpg

The sound you are hearing is coming from the wastegate armature (green arrows in the pic/link above). That 90 degree attachment has a bolt/screw that if you wiggle with your fingers allows some play. I have held my own M6 turbo in hand and recreated the sound with my SA/tech.

Therefore, the sound is normal (although not pleasant to hear). It can get louder with various aftermarket downpipes, as well.

Mark

p.s. Do some searches in the forum for the long drawn out investigation into this problem by many M5/6 owners.

[N.S.A]

Do you hAve non stock Down pipe ?

[RM666]

Thanks you both the info.

After some research I got to the conclusion that the 2015 models don't have this behavior (at least so loud) since they changed something on the wastegate, but on previous year models this rattle would happen, some more than others.

Originally Posted by N.S.A

Do you hAve non stock Down pipe ?

Yes, I have an Akrapovic exhaust system.
I know it exaggerates this rattle, but I have installed the stock exhaust system to test it too, and the rattle is the same.

[aznkuja328]

Originally Posted by RM666

Thanks you both the info.

After some research I got to the conclusion that the 2015 models don't have this behavior (at least so loud) since they changed something on the wastegate, but on previous year models this rattle would happen, some more than others.



Yes, I have an Akrapovic exhaust system.
I know it exaggerates this rattle, but I have installed the stock exhaust system to test it too, and the rattle is the same.

akrapovic doesn't make downpipes for the m6.