F32 ?Trunk? rattle

sodixm · 11-03-2021, 12:09 AM

Maybe this is the wrong place to post this, if it is, I am sorry but here it goes. Two days ago this super loud rattling sound started coming from the rear of my car. This sound ONLY HAPPENS when I go over a decent sized bump (nothing damaging) well I thought it was the plate rattle at first, tightened that, no way that could be rattling this loud... then I thought it was possibly the plastic covers for the booster seat attachments, I taped those down, still I hear this sound. My brother sat in the back while driving over some bumps and we determined that the sound is coming from somewhere inside the trunk. I have nothing in my trunk, never have... What is interesting is that the car only makes this sound on and off, but mostly when the interior is warm, which makes me think its loose plastic but the sound has a metallic ring to it. After listening in the trunk area, my brother thinks its the plastic liner above the hood in the car, so the plastic behind the rear seats over the trunk area. He slapped it a few times and we were able to replicate a very similar sound, but then we weren't able to do it again. Odd... anyone have anything like this happen to them? This sound is loud, and I mean like something is in the trunk loud. If it helps, its a RWD 435i coupe, non-EDC suspension, brand new tires etc, only 50,000 miles on it. Please help me out, this is driving me absolutely mad. I couldn't replicate the sound this morning when I took it out for a spin for 20 mins, but after 30 mins of driving around tonight it started making the sound, all the way home until it stopped towards the end of my cruise.
Thank you! Hopefully this is an easy fix!

zhoushilun · 11-09-2021, 08:46 AM

there is a plastic piece (not sure what is it used for but it is under the rear windshield between the two seat pulls) on the top trunk, take a look at that. I had the same issue that I could not find the noise until I pressed that plastic piece.

sodixm · 02-14-2022, 06:52 PM

Quote:

Originally Posted by zhoushilun

there is a plastic piece (not sure what is it used for but it is under the rear windshield between the two seat pulls) on the top trunk, take a look at that. I had the same issue that I could not find the noise until I pressed that plastic piece.

Sorry this response is super late, but that turns out to be what it is! I think it is a cover or something for the rear breaklight, I am thinking it got disconnected when I had my windows tinted, any fix?

11-03-2021, 12:09 AM	#1
sodixm Enlisted Member 8 Rep 48 Posts Drives: BMW 335i, 435i Join Date: Jun 2020 Location: MI iTrader: (0)	F32 ?Trunk? rattle Maybe this is the wrong place to post this, if it is, I am sorry but here it goes. Two days ago this super loud rattling sound started coming from the rear of my car. This sound ONLY HAPPENS when I go over a decent sized bump (nothing damaging) well I thought it was the plate rattle at first, tightened that, no way that could be rattling this loud... then I thought it was possibly the plastic covers for the booster seat attachments, I taped those down, still I hear this sound. My brother sat in the back while driving over some bumps and we determined that the sound is coming from somewhere inside the trunk. I have nothing in my trunk, never have... What is interesting is that the car only makes this sound on and off, but mostly when the interior is warm, which makes me think its loose plastic but the sound has a metallic ring to it. After listening in the trunk area, my brother thinks its the plastic liner above the hood in the car, so the plastic behind the rear seats over the trunk area. He slapped it a few times and we were able to replicate a very similar sound, but then we weren't able to do it again. Odd... anyone have anything like this happen to them? This sound is loud, and I mean like something is in the trunk loud. If it helps, its a RWD 435i coupe, non-EDC suspension, brand new tires etc, only 50,000 miles on it. Please help me out, this is driving me absolutely mad. I couldn't replicate the sound this morning when I took it out for a spin for 20 mins, but after 30 mins of driving around tonight it started making the sound, all the way home until it stopped towards the end of my cruise. Thank you! Hopefully this is an easy fix!
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11-09-2021, 08:46 AM	#2
zhoushilun Private First Class 22 Rep 106 Posts Drives: BMW 428I Join Date: Oct 2019 Location: miami iTrader: (0)	there is a plastic piece (not sure what is it used for but it is under the rear windshield between the two seat pulls) on the top trunk, take a look at that. I had the same issue that I could not find the noise until I pressed that plastic piece.
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