Weird Metal Popping Noise

[SS32]

So here's the situation. I parked my car for 5 days. I came back and started it up, let it idle for a minute, and pull out. As I pull out I thought I heard something weird, and the car felt a little off, so I pulled over to check if something was wrong. I walk around the car, check the tires, everything seems fine, no weird noises from the engine. I drive 5 minutes home and while going up the driveway I hear it again. What it sounded like was a tin can bouncing on concrete or someone thumping a tin can. I got out, grabbed my flashlight, and looked under the car. I couldn't see anything hanging or hear anything. I pulled the car forward a little and heard it again, and it sounded like it was coming from the rear driver's wheel area. So I got out, checked again, and still nothing. I back the car up and it does it again, pull forward, and it does it again, but this time it sounds like a can dragging the ground, then it pops. I turned the car off and gave it a thorough look over again and still didn't see anything. I tapped the muffler with the rubber handle on a screwdriver to see if anything was in it and couldn't hear anything. I let it sit for 20 minutes or so and when I left to get dinner, I filmed myself backing up. You can hear it pop once, and it hasn't done it since; this was Friday night. I'll get the video up in a minute, but does anyone have any clue what it could have been?


I repeated the noise a few times so you could hear it.

[McLuVan]

sounds like you could have gotten a rock stuck in the barrel of one of your wheels
wait..no nvm
it's dragging on the ground

[dizman7]

Originally Posted by cowmoo32

So here's the situation. I parked my car for 5 days. I came back and started it up, let it idle for a minute, and pull out. As I pull out I thought I heard something weird, and the car felt a little off, so I pulled over to check if something was wrong. I walk around the car, check the tires, everything seems fine, no weird noises from the engine. I drive 5 minutes home and while going up the driveway I hear it again. What it sounded like was a tin can bouncing on concrete or someone thumping a tin can. I got out, grabbed my flashlight, and looked under the car. I couldn't see anything hanging or hear anything. I pulled the car forward a little and heard it again, and it sounded like it was coming from the rear driver's wheel area. So I got out, checked again, and still nothing. I back the car up and it does it again, pull forward, and it does it again, but this time it sounds like a can dragging the ground, then it pops. I turned the car off and gave it a thorough look over again and still didn't see anything. I tapped the muffler with the rubber handle on a screwdriver to see if anything was in it and couldn't hear anything. I let it sit for 20 minutes or so and when I left to get dinner, I filmed myself backing up. You can hear it pop once, and it hasn't done it since; this was Friday night. I'll get the video up in a minute, but does anyone have any clue what it could have been?

Yup, I'm still trying to figure this one out too. I didn't notice it till after the 1200 mile service, but mine was a demo with 900 miles on it, so I didn't have to drive it far to get there.

Anyway, I just dropped it off at the dealer today for that very same issue and I got the answer I was expecting. "We couldn't reproduce the issue, so we couldn't find anything wrong with it"

I have no idea what it is, but some times it's EXTREMELY loud, but the funny part is it doesn't do it all the time, infact I've gone weeks without it doing it (I've had the car for a month and half).

For me here's when I notice it

1) Usually moving less than 10mph, mostly in reverse than forward
2) Usually when it has been sitting in below 30degree temps for a while, or in the garage all night when it's that cold outside (but not in the garage).
3) Usually after it's been sitting off for a while
4) Doesn't do it EVERY time under each of the above conditions, pretty random
5) Stops doing it once the car is moving over 10mph

I've even had it where it'll do it every time I start to move from a stop all day, then not doing again for a week after that day!

UGH, gets me frustrated when I think about it now, cause it'll go away just enough for me to forget about it, then I hear that little ping/ding tin can noise that sends a shiver down my spine.

Dealer guy said it might be the break pads rubbing against the disc but I dunno the pads aren't metal and this is defiantly a metal sound. I wonder if it's something to do with always using the parking brake when the car is off or something.

Enough of my rant, but you are not alone and if you figure it out let me know!

Dealer guy also suggested I try leaving it over night with them, which I'll probably do after I hear it again.

LOL I don't know why I say "dealer guy", he visits this site and knows who I am, ha ha

[FStop7]

I used to have a Mitsubishi Evo that did this. I was out of town for a few days and left the car parked in the airport garage. When I got back I immediately heard a metal on metal sound as I drove out onto the street. I started to slow down so I could pull over and see what was wrong, when I hear a sound like "Ping!" and something bounced off the ground. I never found what it was and the car never had a problem. I think I picked up a small piece of metal or a stone that got stuck around the brakes or something.

[Manny212]

I noticed this for the first time on Sunday. I was backing out of my driveway and heard what sounded to be as the OP described, a tin can bouncing around. It sounded like it was from the passenger side and it only did it while i was backing out and when i started to drive for about a minute or 2. Hasn't done it since then. Might be the cold or the car might just have a mind of its own.

[McLuVan]

oh okay...cold+reverse+brakes could mean that your brakes may be stuck onto your rotors
I hear that happens..when it "pings" that is when the pads bresk free
I also hear it happens after car washes too

[SenorFunkyPants]

Its a stone caught up that is pinging your rear anti (rain) spray guard for a rear disc.

[gr8000]

I think its a small rock / debris moving freely between the back of the rotor and the protective metal shield (protecting the rotor from water splashes). Debris / small rocks get captured in there occasionally and the sound is like you are dragging cans arround! I got it once and it drove me nuts. I was checking the car again and again and couldn't find anything. Eventually the rock / debris was out and the sound stoped by itself. Reason you dont hear it at higher speeds is because of the centrifugal force causing the rock / debris to stop moving freely, or because of the louder ambient noise at these speeds making it more difficult to hear.

[VanM3Lover]

I heard this exact same noise while backing out of the garage a few times when the car was new, haven't heard it since. I figured it's most likely a stone caught near the spray guard as SenorFunkyPants says so I didn't start a thread on this.

Now this might be a little OT, you can skip this if you don't want to read. After turning off the car, there are very light taping noise coming off from the front wheel wells, sounds like tap the rotor with screw driver. But what really gets me worried is that every time after about 30mins, there is a very big popping noise from the right side, sounds like hitting the plastic fender from the inside, anybody know what this might be?

[SS32]

Ok, good to know it's nothing serious.

[J08M3]

I had the same thing happen a few times. Once a few months back then it went away, and again just a couple of days ago. Only at slow speed like when backing into my driveway.

[jaihind]

I HAVE THE SAME PROBLEM....I took it to the service center, they said it was normal for the e92s.

[mabobe]

Originally Posted by gr8000

I think its a small rock / debris moving freely between the back of the rotor and the protective metal shield (protecting the rotor from water splashes). Debris / small rocks get captured in there occasionally and the sound is like you are dragging cans arround! I got it once and it drove me nuts. I was checking the car again and again and couldn't find anything. Eventually the rock / debris was out and the sound stoped by itself. Reason you dont hear it at higher speeds is because of the centrifugal force causing the rock / debris to stop moving freely, or because of the louder ambient noise at these speeds making it more difficult to hear.

I agree with this.
Same issue here too. I brought it in to dealer and had them remove the rear wheel. They could not reproduce the sound, but repositioned the rotor shield. It has been almost a month and no noise to date.

[footie]

This is the exact same noise I took my M3 into the dealers with. I take it the sound seems to be coming from the rear, possibly the rear right hand side?

They had mine in for almost 6 hours sorting this and doing what I reckon with an upgrade on the gearbox.

[dizman7]

Anyone have a picture or diagram to help me visualize where this is at. I've had it make the noise VERY loud sometimes about a month ago, I could here it over the engine with the windows up it was so loud. But it still seems to do it randomly though.

I find it hard to believe it's just rocks, but enough people seem to think so that I'm open to the idea. Anyway that I, myself, could flush these out of there?

[J08M3]

Happened to me again last night while cruising around a parking lot looking for a space. It's weird sounding, doesn't quite sound like a rock. Almost sounds like it's in the exhaust system. Sorta embarrassing while while driving past pedestrians in your $70k car. I hope it's just a rock, otherwise it sounds like something that wants to break.

[gr8000]

Originally Posted by J08M3

Happened to me again last night while cruising around a parking lot looking for a space. It's weird sounding, doesn't quite sound like a rock. Almost sounds like it's in the exhaust system. Sorta embarrassing while while driving past pedestrians in your $70k car. I hope it's just a rock, otherwise it sounds like something that wants to break.

I also thought it was the exhause contracting when cooling off but was wrong. Simple test: does the sound stop when you stop the car? if it does then it is likely it is the rock issue.

[J08M3]

It's definitely not the exhaust and it's only while moving at slow speed. So I'm guessing it's the rock issue. Anyone have a pic of where I can find this rock?

[SenorFunkyPants]

Reversing a few times seems to dislodge it. I had it on mine for a couple of days then it must have fallen out.

[MatthewDavid]

Relatively confident I get the clanging cowbell sound when not moving, just putting it in gear. Both times I've heard this nifty sound I have driven the car, let is sit, then gone back out to drive it. Put it in gear, such as reverse, don't move, hear it. I heard it in the forward gears too, but not sure how this could POSSIBLY be a rock. It of course goes away, but guess that could be a rock dislodging or metal heating back up and eliminating the popping. Shit, hell if I know... scared me the first time. Thought I ran over someone's pet cow.

[dizman7]

I had this act up again a week ago. Took a business partner out to lunch and it made it really loud the whole time, very embarrassing, then by the time I got off work and took it to the dealer it completely stopped! I was pissed! Had the guy there look at it with me for about 20mins and not a peep.

Not sure if it's rocks but I was looking in the wheel/wheel well today (thought I heard it but it was actually the super gusty winds making weird noises going around and under the car) and I did notice if you flick the black metal pan (for lack of better words) that is right behind the disc brake, it'll make the exact same noise. So the idea of something caught in between that and the brake disc does seem more valid to me now.

I can sort of reproduce the noise. maybe next time I just throw rocks in there myself so the dealer will take the wheel off and look!

[gr8000]

Originally Posted by TraydenBellean

Relatively confident I get the clanging cowbell sound when not moving, just putting it in gear. Both times I've heard this nifty sound I have driven the car, let is sit, then gone back out to drive it. Put it in gear, such as reverse, don't move, hear it. I heard it in the forward gears too, but not sure how this could POSSIBLY be a rock. It of course goes away, but guess that could be a rock dislodging or metal heating back up and eliminating the popping. Shit, hell if I know... scared me the first time. Thought I ran over someone's pet cow.

Since your car is stationary when this happens probably makes it highly unlikely that in your case it is a rock / debris between the back of the brake rotor and the protective metal shield. Must be something else... VERY strange. When you find out what this is please keep us posted.