?wheel bearing noise
 

I have yet to put my caron the lift to look but having driven the car for the 1st time since last October, there is an added noise - rather like a loud humming. How can one tell it is the bearing, and how would you identify which one is the culprit w/o changing all 4?
Is it reasonable to do DIY?

Nothing magical about pressing out, pulling, or installing new bearings as long as the right tools (bearing press and/or puller) are available. (EBS tool)

http://p-car.com/diy/bearing/bearing.htm

Very straight forward job...Setting the play/tension on front wheel bearnings takes a knowledge and feel for what is "right"

can you rule out the tires?

I've never felt like describing a bad bearing as humming. I'm with mag, thinking tires could be funky from sitting.

I've had two wheel bearings die on me, both rear, different sides and different 993s.
sounds like driving over an old concrete slab highway, faint thump, thump, thump....
I heard no humming, so maybe tires, maybe bearing, or may be the parking brake.
could be a wheel well liner has dropped and is rubbing the inside of the tire.
once you get the car on a lift get a wheel spinning and listen to the wheel carrier with a stethoscope.
if there isn't any grinding noise you can rule out the bearing.

Wheel bearing
 

When driving freeway speed, steer like you are warming your tires up at the track. You will likely hear changes in the sound when the suspect side gets loaded. This is what was happened to mine. I changed the rear wheel bearing and the sound was gone.

Definitely can rule out tyres.

I kept the car slightly raised on lift so tyres not bearing the wt of the car.

Your description of driving on worn concrete is spot on but is louder.
I've not looked under the car so cannot tell if any other bits are loose but turning wheel by hand, all 4 wheels have a faint metal sliding on metal sound so how could I tell if bearing is bad. I could take it to a repair shop but would like to learn to deal with doable stuff myself even if it means buying a press.

The only way I've been able to diagnose wheel bearings -vs- tires is on flat ground, with the car off. Push it and listen. If it's a bearing, you will hear it, and you can pinpoint which one it is.

Good luck!

the faint metal sliding on metal sound is the parking brake or disk brake.
get a stethoscope from an auto parts store, car in the air wheel spinning.
even with the engine idling, tranny in 2nd gear and loud exhaust, stethoscope on
the wheel carrier, the crunching noise of a bad bearing will be obvious when you hear it.

It so happens I have a real stethoscope :D I'll find some time to do that :cheers:

In my case it was more of a constant "singing" from the back at ~30mph+ that varied purely with road speed and no relation to engine speed. Unlike the S4, I couldn't detect any difference by loading up one side vs. the other to distinguish which side. Once I'd decided it was a rear bearing and assuming one side was worse that the other (like with the S4) I jacked up the back and compared the noise from spinning each wheel by hand. Driver's side won by a nose... changed it out using EBS kit and bearing. "I chose wisely" (apologies to the Grail Knight :-).

Tony

If you determine its the rear wheel bearing(s), you might consider doing both sides at the same time.

My car just is in the shop to have a bearing addressed. When you turn, it sounds like driving on a washboard. Have a close look at your wheel hubs, they often need replacement too to get a long-term solution. I will replace mine. And because it is a DE car, I just do the bad side (but right) and wait for the other side coming due. No reason to make an early investment here as I am not saving anything "while I am in".