red_wings05

The last week or so I have started to hear a strange sound when driving.
It sounds a bit like when two plastic parts are grinding against each other.
It doesn't start immedatly but rather a 5-6min into the ride. When applying presure to the throttle the sound doesn't increase in loudness but it the "grinding" becomes quicker if you get what I mean.

First I thought it was just something loose in the glovecompartment but it wasn't. Does anyone have any idea on what it can be? There is no power loss and I don't feel any vibrations.

I have done a recording to day of the sound and you can hear it on the link below.

MVI_0494.flv - Video - Photobucket - Video and Image Hosting

Thanks in advance.

marckula

what work have you had performed recently? that sounds like loose suspension mounts or perhaps your seats? good idea recording it though.

red_wings05

Only work done recently was installing an X-pipe, but I have driven about 3000km since then.

I have had a "swoshing" sound from, most likley, the suspension when driving over speedbumps for a long time. But that mostly occure when the car or the weather is really hot and not always. I just assumed that they were starting to wear down. What is the expected lifespan of the suspension? My car has about 117000km (73000miles) on it.

nerio02

suspension mounts was the first thingthat came up to me too...but the OP said it occures after 5 min. so that could not be then

strange sound ..

maybe exhaust thats loose or your guibo thats alsost shot.. try to have a look underneath it.

__________________
with kind regardes

nerio02/dominique

red_wings05

nerio02: Maybe it doesn't take 5min to occure but I don't hear it immediatley when I take off. Can the suspension "mounting sound" graduatly increase until one hear it or should you hear it from the start?

Is it just to tighten the mounts or does anything need replacing if this is the issue?

What is guibo?

Thanks for quick response from both of you.

marckula

if you had the exhaust worked on that would be the first place I'd look - check the mounts and make sure the bolts are on tight.

with regard to the suspension - from what i've read around this board and others is that a stock suspension begins to wear around 50000 - 75000 miles - particularly thrust arm bushings and rear ball joints. shocks are said to be good until they begin leaking.

but, those issues wouldn't necessarily be causing the sound you recorded. i had a similar thunking sound when i upgraded the front springs on my old e34 540i - the strut mounting bolts weren't on tight enough which caused the metal mount to bang against the chassis. re-torqueing the strut mount bolts solved that immediately.

if the sound becomes more frequent when you're driving over bumps then something is probably loose.

red_wings05

Will try to have a look at it this weekend. Thanks again for your help.

nerio02

well the suspension mounting top is like a rubber with on both sides a metal plate,sometimes after some years ,cars that driven on bad roads can have the rubber torn by age and "road abuse" . the rubber tears and eventually can break up and the two plates knock on eachother,what gets amplified by the body off the car...
most off the time you only hear it on bad roads.. on a perfect road without bumps it can be harder to notice it.iff you drive can you feel like the car sometimes want to tilt a bit instead of being smooth and flat in corners? that is also a indication something has space to move around like it shouldent.
iff you press on your car , you can hear the sound also sometimes iff a top mount is gone. just be carefull not to overpress and dent the car

the guibo is the rubber donut between te engine and the drive line to the rear diff.. that can produce also a knocking sound because it has some space to move around.. i doubt that its that because yo can feel it in the shifter, but i wanted to mention it anyway.


if you had your x pipe installed, they had to remove a exhaust hanger plate right after the cats and afterwards they installed it back. maybe its the x-pipe thats hitting that exhaustplate when its warm and a bit expanded.normally between the x-pipe and the exhaustplate there are rubber bushings also maybe the forgot those and thats why the plate is closer to the x pipe , with ratteling noise as result when driving.

a worn thrust arm bushing or rear ball joint or a wheelbearing thats going could cause this sound also like marckula suggested .

just some thoughts though..worth to check it out.

__________________
with kind regardes

nerio02/dominique