Greetings helpful internet folks,
I've been googling my ass off about my new-to-me 2018 M3 LR RWD at 85k, and am admittedly stumped.
There is a strange clunking or knocking sound emitted from the front passenger area that increases with more acceleration, i.e. undetected under calm/casual, somewhat apparent with moderate acceleration, and very noticeable under full pedal.
I manipulated a recording from my phone to reduce low-freq to suppress road noise, and make it sound more similar to what I hear with my ears. This made the sound easier to hear, but keep in mind the concerning clunking/knocking sound is much deeper and booming in real life:
Knocking.mp3
I do NOT believe this is interior panel vibration.
As this is RWD, there's no halfshaft/CV or anything like that present, so I'm puzzled about what could be making this sound.
Maybe the antisway bar? I tried to wiggle it, and the other elements of the suspension/linkages, and they all seemed solid to me, but maybe I need to learn how to examine this better.
I'm unsure if this is related, but given the area of concern is the same, I'm inclined to believe it is.
The car made a mystery discharge of some brown fluid which hardened into a shellac-like substance after a bit as pictured:
The under-frunk area seems to be clean:
There is an unusual streaking portion, about where the mysterious brown fluid came from in the seam between the undercarriage panels:
Under the rear motor, there seems to be some staining:
Wheel wells appear to have some droplet stains:
I've been googling my ass off about my new-to-me 2018 M3 LR RWD at 85k, and am admittedly stumped.
There is a strange clunking or knocking sound emitted from the front passenger area that increases with more acceleration, i.e. undetected under calm/casual, somewhat apparent with moderate acceleration, and very noticeable under full pedal.
I manipulated a recording from my phone to reduce low-freq to suppress road noise, and make it sound more similar to what I hear with my ears. This made the sound easier to hear, but keep in mind the concerning clunking/knocking sound is much deeper and booming in real life:
Knocking.mp3
I do NOT believe this is interior panel vibration.
As this is RWD, there's no halfshaft/CV or anything like that present, so I'm puzzled about what could be making this sound.
Maybe the antisway bar? I tried to wiggle it, and the other elements of the suspension/linkages, and they all seemed solid to me, but maybe I need to learn how to examine this better.
I'm unsure if this is related, but given the area of concern is the same, I'm inclined to believe it is.
The car made a mystery discharge of some brown fluid which hardened into a shellac-like substance after a bit as pictured:
The under-frunk area seems to be clean:
There is an unusual streaking portion, about where the mysterious brown fluid came from in the seam between the undercarriage panels:
Under the rear motor, there seems to be some staining:
Wheel wells appear to have some droplet stains:
