Thats the A/C fan, and the same problem i had on my A4 a few years back.
A bad valvetrain in this particular car would make it sound like a ford diesel engine, definately not what you're experiencing. No CEL's would be tripped from bad valvetrain. You would get an oil pressure light before you ever heard any valve train problems. You can find those fans online for much cheaper at the dealer. Check
www.ecstuning.com
www.purems.com
www.germanpartsonline.com
www.jhmotorsports.com
www.blauparts.com
The last one is probably the best for the A8.

 

Excellent. Would I have to disassemble the front end to service this particular part? Is there any way to fix it by lubricating it instead of replacement? I guess my main question is -- what is causing it to make this sound? Maybe the plastic is simply contracting due to cold, causing the fan to touch the casing? Supposing I turn the A/C off, would this fan turn off?

http://stores.channeladvisor.com/Fre...itemid=3801780

Would this be the part? The compatibility chart says it will fit the 2000 model A8.

 

I tried lubricating mine with no avail. I broke down and spent the $200. You really only have to take off the bumper and unbolt the lock carrier, you can use the allan bolts taken from the bumper beam to support the carrier and pull it forwards without disconnecting anything. Its actually quite easy and usually takes less than an hour to do. Essential knowledge you should know how to do i might add if you plan on owning an older audi in the first place. The bearing inside the fan is causing the problem, so there isn't any fixing that besides replacing the fan.
Im not familiar with the link you provided but yes thats the fan that needs replacing. It says it "should" fit doesn't sit with me too well though....

 

I could always return it. I noticed that if I run the A/C in economy mode, the fan isn't used so I'm content with that until the spring/summer where I will need more powerful air conditioning.

I also noticed that upon putting the car in gear, the engine sounds different... probably due to the RPMs decreasing, but I wasn't quite sure... do you have any input on this?

Thanks again. I know I'm probably just suffering from an overly critical subconscious or something to that effect, but I just want to make sure the car is in good running condition.

 

Yes, if you hit the ECON button the A/C is completely turned off, so its gonna get hot when it hits 70 degrees above.

I can't really comment about the engine noise in gear, every engine sounds different under load. Unless there is a fault code in the ECM or TCM, there isn't anything i can do about it.

 

Ok, the car is running well. However, there is an odd sound from the front of the car when braking... perhaps the rotors need to be turned.

How can I remove the timing belt cover to inspect the belt's condition?

 

You have to unbolt one of the upper covers, usually has 10mm bolts or allan bolts holding them on. You can't turn audi rotors, the metal is too soft. I mean you CAN turn the rotors but the pads wouldn't last more than 10k because it would get so hot from taking so much material off the rotor surface. Sounds like you bought a basket case.

 

I wouldn't say that, everything works. I think it just needs some minor maintenance to bring it back up to snuff.

 

Heres to hoping. Cheers!