Audi A3 buzz/resonate at 2.8-3k rpm

[Mihkel]

Hello

Car I’m taling about is from year 1997, 2 door Audi A3 with 1.6l engine. I had exhaust checked yesterday – mechanic told me that exhaust is fine.
There is a video of a sound also:
https://www.youtube.com/watch?v=6eeD1dy-7FA
(video itself is black). It starts from 2.8k and ends at 3k rpm. If I hold rpms in that area, the buzzing wont go anywhere. It is there on all gears. But not on neutral. It does vibrate also a bit as I cannot put my house keys to center console anymore.

Any help would be appreciated.

Topic

[Ben]

hi
I couldn’t hear the sound on your recording very good.

where would you say the sound is coming from? does it sound like an engine noise or is it more vibrating plastic within the car? does it make the noise when in gear at 2.8-3k rpm but stationary.

Some more info would be good, If it makes a noise when stationary at the suggested rpm could you record the noise and have someone keep the rpm’s up while you record and walk around the car to try and figure out where roughly its coming from, It would help a lot if you know where roughly its coming from.

[Mihkel]

Thanks for the reply.

I recorded a way better videos, windows opened, windows closed, stationary, camera outside while driving etc. It does not make that noise stationary so it is hard to trace the buzzing component. When i’m driving it feels like it is coming right from the bottom. Near the flex and downpipe.

Video:
https://youtu.be/sbThadP1lVk

[Ben]

Hi
its a strange one that, But it sounds like something is vibrating and for it to vibrate at 2.8rpms and no other rpm’s.

to me its sounds like the heat protection cover which is just above the front down pipe is rubbing against the exhaust, its flexable and easy to maneuver. Do you feel any vibration in the steering wheel or any of the pedals?

Here is a good way to figure out where its coming from, Take your car to a garage that has a rolling road put the car on the rolling road and get the car to rev to the 2.8k rpm’s then scout around the car for the sound. The garage wont charge you for this and it means you can walk around the car while its moving which would make it more easy to diagnose where the sound is coming from.

To me tho it just sounds like the exhaust heat cover rattling on the exhaust.

[Mihkel]

Yes. I can feel vibration. The keys in video also show that.
Do you mean the flex pipe, on the left side of image?
http://www.vyfuky-tyll.cz/e-shop/obrazky_sys/C020187.gif

[Ben]

No, its not on the pipe its above the pipe and made of aluminum, look just after where the O2 sensor is on the exhaust, then look above the pipe, Its a heat plate that protects the car from the heat of the exhaust, its not actually attached to the exhaust it looks like its attached to the floor but underneath the car.

But if you can feel it through the steering wheel then its more than likely a wheel bearing on its way out.

the heat plate looks like this

[Mihkel]

Thank you. I will check this tomorrow. It is not wheel bearings because I changed them all like 4 weeks ago. Bought accidentally rear ones but wanted to change front ones. You mean next to exhaust manifold, am I right? O2 sensor on my car is connected to catalytic converter but I know that some cars have it connected to manifold.

[Ben]

Take your car to the nearest garage (most have a rolling road) and ask them if you can put your car on the rolling road. you’ll be able to pin point the noise more easily. (the garage wont charge for this).

A rolling road is where they test the brakes and look like 2 giant rollers that your wheels can go on. you can then take the car to the required rpm’s and will be able to find more or less exactly where the sound is coming from.

[Mihkel]

I think I found the reason for the noise:

I was unable to take it off. Is it possible to fix it or does it need replacement? After I bent the plate the sound went a bit different.

[Ben]

Hi

You can just bend it so its not rubbing on anything, Check the very front of it as well, to make sure when your driving the wind does catch it which could cause it to vibrate. I had mine vibrate after i had the exhaust changed and it wasn’t put back correctly. So what i did was to take a hammer and a piece of wood and knock it into place so it was all snug against the undercarriage.

[Author]

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