It is sounding more and more like a PS bearing, but it is still hard to be certain using a s/scope. Does anyone have experience with purchasing / replacing a PS pump on the 96 A6?

I'm trying to figure out what my engine speed/road speed noise is... and it's driving me crazy worrying about it! =)

If you are asking how to tell the difference between road noise and engine related noises, such as the whine I refered to: the whine of a bearing going bad in, say an belt idler, water pump, generator, or PS pump, is that you can hear the pitch increase with engine speed, either at idle, or in every gear as you increase from rest to 50 mph or so; road noise either appears at a particular speed, regardless of engine speed, or steadily increases as mph goes up, regardless of what gear you are in. So, shift out of OD, for example, and see if the pitch changes.

I'm trying to track down what my problem is... but I don't think I know where to start. here is my original post...

http://forums.audiworld.com/a6100/msgs/23502.phtml

my problem seems to be related to road speed... as I shift from 3rd to 4th gear on the freeway, the sound seems to not be related to the gears shifting (engine speed changing).

any thoughts? could it be a pump or pulley still? I changed my t-belt, t-belt idler roller, t-belt tensioner, v-belt and water pump about 5K miles ago... did the service myself... but this problem just popped up...

You have a different problem entirely, I think. My whine is linked to the engine RPM and sounds like a bearing: it gets louder and the pitch rises with RPM. I can hear it through a probe stethoscope, very loudly right by the PS pump. Unfortunately, it can be almost as loud elsewhere. Audibly, even with a funnel and pipe amplifier, the sound is hard to pinpoint.
You mentioned that your problem occurs more at or after the point your car shifts from 3rd to 4th, and seems related somewhat to road speed, at least until the wind noise drowns it out. Transmission doesn't seem very likely, but it would fir the picture. Are you sure that the same RPM in lower gears doesn't cause it?

listening for the sound when I'm sitting in a parking lot. From 0-35/40mph (gears 1-3) I can't really hear the extra noise. I'm going to pop the hood and have someone gas while I listen.

someone has suggested the fuel pump as a possibility... but I would imagine the whine/buzz would be audible throughout all speeds....

when I first heard the sound, it fooled me into making me think the car had not shifted into 4th gear and was still running on 3rd gear at higher speeds... but that is because the sound stays constant during the shift from 3->4... and sometimes is just as loud as the engine noise

and bring up the rpms with it on or off. if it makes noise with the ac off, then it is the AC clutch idle pulley. i had that problem last year. changed the clutch/bearing.

jim

very annoying, especially in first and second gear acceleration. Replaced the pump, and everything works great now.

Any tips you have regarding this job would be appreciated. Info on how not to drain 50 bucks worth of Mineral Oil on the driveway would be a good start; I just took a big hit on the bill from the mechanic who did the rack job!
Thanks.
Limey