Mild whine from transmission/drive shaft/wheel bearing?

antiskeptic

Hi,

I've an Audi A4 2007 with 90K miles up. There's a road speed related whine coming from somewhere at the front end. Best I can describe it:

- turbine sound, high pitched
- mildly modulating/pulsating but at a high frequency so sounds almost continuous pitch

It doesn't sound too loud from inside but definitely there over the engine noise. When I open a window and am driving along say, a long wall, you can hear it reflecting back quite loudly.


Any ideas what components might be implicated. And how to go about isolating which one?

Cheers..

TomOnBoard

antiskeptic wrote: »

Hi,

I've an Audi A4 2007 with 90K miles up. There's a road speed related whine coming from somewhere at the front end. Best I can describe it:

- turbine sound, high pitched
- mildly modulating/pulsating but at a high frequency so sounds almost continuous pitch

It doesn't sound too loud from inside but definitely there over the engine noise. When I open a window and am driving along say, a long wall, you can hear it reflecting back quite loudly.


Any ideas what components might be implicated. And how to go about isolating which one?

Cheers..

Any recent work done?

antiskeptic

TomOnBoard wrote: »

Any recent work done?

No. I bought it last November and didn't notice it then. I only use the car for school runs and you wouldn't be building up speed such as to notice it much, but if your on a longer run, it's there alright (it's definitely noticeable from maybe 30mph but once you've noticed it, you can follow its presence down to 10mph or so)

TomOnBoard

You'll need quite precise hearing to determine whether it's coming from front or rear. Put some one in the back while you drive at varying speeds and open each window in turn to be as precise as possible about which corner of the car might be involved.

Check the centre of the wheel on each corner and assess whether any corner is hotter than the other corners after a trip. That's to see if a bearing/hub is at fault. Be careful!! They can get really hot.

If wheelhubs aren't getting unduly hot, it may be a brakes problem. Does the sound change when you press the brakes?

Has the car got aircon? Is it switched on? Turn it off and see if the sound changes.

antiskeptic

TomOnBoard wrote: »

You'll need quite precise hearing to determine whether it's coming from front or rear. Put some one in the back while you drive at varying speeds and open each window in turn to be as precise as possible about which corner of the car might be involved.

Check the centre of the wheel on each corner after a trip and assess whether any corner is hotter than the other corners after a trip. That's to see if a bearing/hub is at fault. Be careful!! They can get really hot.

If wheelhubs aren't getting unduly hot, it may be a brakes problem. Does the sound change when you press the brakes?

Has the car got aircon? Is it switched on? Turn it off and see if the sound changes.

Thanks.

Will do on the the locating. Good idea.

Understood on the hub.

The sound reminds me of the slightly ringing/brushing noise you hear when you spin the front wheel of a motorcycle

Doesn't alter with pressing the brakes, no. I do recall, now that you mention it, a service docket mention discs being replaced, which struck me as usual for a car that mileage. I'll check the temp of those carefully after a brake-lite run.

The the aircon/blower. Not it.

Peatys

I had the same in a 08 bmw e92 with 130k kms.. Was coming from gearbox. Replaced oil and filter, haven't heard it since.

Sam Quentin

Alternator pulley or wheel bearing?

antiskeptic

Sam Quentin wrote: »

Alternator pulley or wheel bearing?

Wouldn't pulley be engine speed related. Indeed, I had a go of turning off the engine and coasting in neutral and the noise continued.

(reminds me of the time my drivers window up button wasn't working. I forgot, pulled the window down to have a smoke and began to freeze - it was in the bleak midwinter. Got the not-so-bright idea of turning off the engine, coasting, removing the key, pressing the lock fob which would close the window. Just as I got the key back in, the steering locked. Muppet!)

Sam Quentin

Well then it's not the pulley so,.. Possibly a wheel bearing, are you getting any kind of wee 'gritty' feeling coming through the accelerator on to your foot? It's hard to distinguish, but if it's happening you'll feel it....

antiskeptic

Sam Quentin wrote: »

Well then it's not the pulley so,.. Possibly a wheel bearing, are you getting any kind of wee 'gritty' feeling coming through the accelerator on to your foot? It's hard to distinguish, but if it's happening you'll feel it....

I'd be fairly attunded mechanically and no, nothing like that. Car is smooth as can be - feels fresh and tight all round. Cept for this whine.

Sam Quentin

You might have a sticking/failing caliper,. Maybe the brake pad is rubbing very slightly on the disc?????
Am just throwing possibilities out there

blackbox

Wheel bearings usually make a hum rather than a whine.

It might be from the transmission / differential. Probably nothing to worry about - turn up the radio.

... or you could try changing the transmission oil; If it's transmission this will probably quieten it for a month or two.

MrCostington

blackbox wrote: »

It might be from the transmission / differential. Probably nothing to worry about - turn up the radio.

.

LMAO!


You could try jacking up each wheel and see if you notice anything turning them (in the forward direction)

9935452

MrCostington wrote: »

LMAO!


You could try jacking up each wheel and see if you notice anything turning them (in the forward direction)

And check for play in the bearings when its jacked up

standardg60

And check you haven't split a boot and have a cv joint running dry.