Mystery noise (audio)

[SoCalZman]

Mystery noise time. Listen carefully to the whole thing (headphones maybe?). My phone is recording audio under my passenger floor mat up against the front firewall. I am stopping and starting the car leaving a parking lot, and making a turn at some point before accelerating up to speed to another stop. Noise happens in all instances (don't think its related to brakes).

https://soundcloud.com/socalzman/car-noise

[SoCalZman]

Solved. mechanic sourced the noise to the subframe. He said the bolts were not loose so I am not sure how it was making all that noise but they reset the subframe and its bolts and the noise stopped. Car is totally quiet and solid. All I had to pay was an hour of labor. I am happy.

[alexandre]

I have a similar noise and was suspecting the same as my entire suspension is brand new. Glad to know it was a simple fix. I'll have mine looked at stat!

[slater]

front or rear subframe?

[SoCalZman]

I have a similar noise and was suspecting the same as my entire suspension is brand new. Glad to know it was a simple fix. I'll have mine looked at stat!

Yeah? I have googled front subframe noise and it is VERY common on Volvos and VWs but yours is the only other e46 I have seen. I am kind of glad I am not the only e46 with this issue, haha. Mechanic said he has had to do this on some X SUVs but not a e46. They found the source by putting the car on a lift that was under the wheels (not jackpoints) and turning the wheels left and right and followed the creaking. Then the supported everything underneath, loosened some of the bolts, and retightened everything to spec. Noise gone. only had to pay one hour labor. Take a look and report back, please.


front or rear subframe?

Front subframe.

[SoCalZman]

looks like this issue might be more widespread on e46s. http://forum.e46fanatics.com/showthread.php?t=1052922

If you have any groaning or popping coming from your front end you might want to get this checked out.

[derbo]

Solved. mechanic sourced the noise to the subframe. He said the bolts were not loose so I am not sure how it was making all that noise but they reset the subframe and its bolts and the noise stopped. Car is totally quiet and solid. All I had to pay was an hour of labor. I am happy.

Glad you found it Antone!

[alexandre]

So I've been reading about this and most people with this mystery sound traced it to the front subframe or the chassis reinforcement plate. Turns out the latter's 8 bolts are single use. I must have removed and reinstalled them 3-4 times since I've been driving this car...

I just ordered the 4 front subframe bolts and 8 reinforcement plates bolts for $35.04 at FCP. I'm gonna replace all of them and torque them to spec - I'm really hoping that this makes the sound go away. I'll post an update in this thread when I do the job!

[SoCalZman]

keep us updated. Are you going to do one at a time (subframe first then plate) to find out which is making the noise or just replace both?


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[alexandre]

It'd be better to isolate the problem... But then I don't fancy jacking the car twice, it's enough of a PITA as it is in my inclined driveway! I'll see what I'm down for when I do it.

[alexandre]

A little update on this:

Went under the car tonight. Replaced sway bar bushings (the rubber ones, not endlinks). Supported front subframe and replaced all 4 bolts on there, torqued to 110Nm spec.

Where things get more complicated is that the last bolt of the reinforcement brace snapped in the frame. I decided to not waste any time on it, buttoned up everything except the brace and will drop the car off at the shop first thing tomorrow.

The good thing is that over the 2 miles I drove without the brace, the car was dead smooth and no pirate ship noise. Pending removal of the broken bolt and reinstallation of the brace I'm confident this will be the final resolution.

[mLuMaN83]

Nice!

[slater]

So I've been reading about this and most people with this mystery sound traced it to the front subframe or the chassis reinforcement plate. Turns out the latter's 8 bolts are single use. I must have removed and reinstalled them 3-4 times since I've been driving this car...

wow, those are stretch bolts, huh? hmmm. it makes sense that a subframe bolt would be, but not the brace. oh well. ya, i've removed mine a few times, too...



A little update on this:

Went under the car tonight. Replaced sway bar bushings (the rubber ones, not endlinks). Supported front subframe and replaced all 4 bolts on there, torqued to 110Nm spec.

Where things get more complicated is that the last bolt of the reinforcement brace snapped in the frame. I decided to not waste any time on it, buttoned up everything except the brace and will drop the car off at the shop first thing tomorrow.

The good thing is that over the 2 miles I drove without the brace, the car was dead smooth and no pirate ship noise. Pending removal of the broken bolt and reinstallation of the brace I'm confident this will be the final resolution.


nice. so do you think it was the subframe bolts (seems unlikely) or the reinforcement brace bolts that had stretched too much? i can't imagine they would creak if torqued properly, even if they are stretch bolts... but, then again, stranger things have happened.

peter

[UdubBadger]

nice was gonna say i had a similar noise, turned out to be loose strut that needed to be tightened down

[alexandre]

nice. so do you think it was the subframe bolts (seems unlikely) or the reinforcement brace bolts that had stretched too much? i can't imagine they would creak if torqued properly, even if they are stretch bolts... but, then again, stranger things have happened.

peter

There were 3 that were finger tight. That's probably where the creaking is coming from. They were a mess of rust though, so I'm not regretting replacing them.

At the shop right now to get that stud outta there.

[alexandre]

Bolt was drilled out and replaced. Everything put back together, reinforcement plates torqued to spec. Problem is finally solved - car rides smooth as butter now. Been looking forward to this day forever!

:happyspidey

[SoCalZman]

wo ho. glad it was fixed! Hopefully neither of us will have to retighten the subframe bolts again in our ownership!

[slater]

There were 3 that were finger tight. That's probably where the creaking is coming from. They were a mess of rust though, so I'm not regretting replacing them.

At the shop right now to get that stud outta there.

which 3 were finger tight - on the subframe or the reinforcement plate?

glad you got it sorted!

peter

[alexandre]

On the plate. While I think Zman's loose ones were on the subframe.