AWSX1686
AWSX1686 UltraDork
12/3/19 8:06 p.m.

2001 Miata. 

Hey all, this noise started today and I'm a bit stumped at the moment on what it is. 

It happens some/sometimes in 1st when accelerating heavily, but is most prominent right after shifting into 2nd and accelerating heavily. When I just leisurely drive, I don't get the sound.

I can tell it's something behind me. It almost sounds like something is resonating just right to rattle around, but I haven't found anything loose. I cleared everything out of the trunk and parcel shelf. 

I kinda doubt that it's the rear, because I feel like I would hear something from that pretty much all the time, not just under heavy acceleration.

 

I did notice that one of the PPF bolts in the diff is missing. Not sure if that's related or not, but by the looks of it, it's been missing a while, so I kinda doubt it. 

 

Link to video with the sound: https://photos.app.goo.gl/R4xBUydfaoPS6xKF7

Floating Doc
Floating Doc SuperDork
12/3/19 9:51 p.m.

Weird sound. Anything loose in the exhaust, brakes, etc.?

Keith Tanner
Keith Tanner MegaDork
12/3/19 10:42 p.m.

Hard to tell from the video, but a cracked heatshield maybe? Like on the cat in the midpipe?

AWSX1686
AWSX1686 UltraDork
12/4/19 5:26 a.m.

I didn’t notice anything when I looked, but I’ll have to double check. 

Foxworx
Foxworx Reader
12/4/19 6:31 a.m.

I got a weird noise in an Integra when part of the Catalytic matrix broke loose inside the housing.

 

 

Keith Tanner
Keith Tanner MegaDork
12/4/19 8:20 a.m.
AWSX1686 said:

I didn’t notice anything when I looked, but I’ll have to double check. 

You’ll want to,tap,or,bang on it. 

Floating Doc
Floating Doc SuperDork
12/4/19 8:26 a.m.
Keith Tanner said:

Hard to tell from the video, but a cracked heatshield maybe? Like on the cat in the midpipe?

I agree, it sounds like a sheet metal harmonic. Heat shield is likely.

Also, do backing plates rattle like that?

AWSX1686
AWSX1686 UltraDork
12/4/19 1:51 p.m.
Keith Tanner said:
AWSX1686 said:

I didn’t notice anything when I looked, but I’ll have to double check. 

You’ll want to,tap,or,bang on it. 

For sure. When I looked last night I was mostly looking at the hose clamps holding on an additional heatshield, but they were all good and tight.

It's mostly just re-assuring that the general consensus agrees that is sounds like a sheet metal harmonic, as I thought. I looked over the general driveline and running gear of the car and didn't notice anything out of place, but naturally my mind goes to that as worst case scenario. Probably not going to have major issues driving with a loose heatshield, something in the drivetrain or suspension though, not so much... 

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