Hello people. Long time lurker, rare poster, but my one thread has helped many people w/ flickering lights in the past so hopefully I'll get some answers here and continue to help people in the future.

As the title states, I have a 2012 Touring hatchback and it's easily the most fun car I've ever had. I am forever in the Mazda family now as a result.

About a month ago, I started noticing a very loud, annoying rattling coming from under my car. It is very apparent over any imperfection on the road. I have isolated the noise (or so I think) to this area of the car. The image is below. The circle was from a different attempt to show people the area in which the sound was coming from but I have since put my car on a ramp and I believe it's coming from where the arrow is pointing. If I'm not mistaken, the bulging area that is circled in the spare tire housing compartment, right? There is a metal bracket (for lack of a better term) that is going down the car and then it connects where the arrow is pointing. I believe this is where the noise is coming from. Here is the image from the passenger side of the car:

https://i.imgur.com/IvrO8Yo.png

The quality of my ride is not impacted at all by this nor does it seem like it's compromising the safety which is important to me as a have a 35 mile highway commute.

In order to get a better understanding of the annoying rattling sound, I took a very sloppy video b/c I feel the sound might give more detail as to what the issue is. Keep in mind, I am lightly tapping on the compartment and if I were to hit it harder, the sound is much louder.

Here is that video:


At first I thought it was the sway bar bushings needing to be replaced b/c I know Mazda has had problems w/ that w/ these cars. Those were replaced last week and I was so excited to get back in it and not hear the embarrassingly loud noise but nope, didn't fix it. I should have probably got under the ramp first before assuming to be honest but that's my mistake.

I am hoping someone here can say "yes, I've had that problem in the past and this and this needs replaced". Honestly, it sounds like a loose bracket but I'm not too much of a car person to say what it is and it isn't. Hoping this forum can help me out.

If you have any ideas, please let me know as well as if more info is needed. It doesn't seem like it's impacting my ride quality at all but it is noisy and embarrassing.

Thanks in advance!!

 

Do the noise vary depending on how much fuel you have in the tank?

 

Unfortunately not. In my research since posting, I'm hoping it's a loose fuel tank strap but I've realized that braking lessens the noise as well. It's driving me nuts lol. Hoping to get it figured out Monday

 

Did you ever find the cause of this noise?

My 2012 Mazda 3 2.0L Sedan is having the same issue and I cannot figure it out for sure.

I have bought a used fuel tank that's sitting in my trunk right now, and when I hit the tank it makes a similar noise. It sounds like this valve inside the fuel tank: https://www.tascaparts.com/oem-parts...alve-lc7742980

I was able to reach in and remove the bottom part of this on mine, and I discovered it has a bottom piece and a spring. I'm wondering if maybe this spring has gotten "limp" over the years and now it just allows the bottom plastic piece to rattle up and down?

Noise is driving me nuts!

EDIT: The Baffle (the large metal piece with holes in it inside of the fuel tank) seems to be just fine, only this valve makes me suspect. I have to stick my entire forearm into the tank (be careful, some parts are sharp) to reach it.