I recently purchased a 2000 A6 2.7 biturbo I now notice a noise coming from the engine bay when the car is idling and warmed up( not present at first whencar is cold)it almost sounds like a diesel rattle when I rev it up it goes away as soon as the car idles down it comes back..any ideas? Ihave a 30 day warranty (power train)that runs out in three days so if this is critical ie; timing belt, water pump, or turbo i need to know so I can pursue getting it taken care of by used car dealer, what I don't need is a huge repair bill since I just shelled out 2,500.00 on down payment and a car loan to boot since I am disabled with MS. and on a fixed income I am desparate for some advice

 

serpentine belt tensioner maybe?

 

Might be shot bearings on around the pulleys?? Check to see if you fan is hitting anything in the engine bay, see if its hitting the pipes at all

 

Thanks for your response as I look it appears that the fan is NOT hitting any pipes to clarify noise a little better ....it has that dull sound of shaking marbles in your hands.... in other words I noticed NO noise nice and quiet as it idled and a few days ago this dull rattle(louder with hood open) started (only when idling) which when revved up a little it tends to go away ...probably as rpm's go up pully's move faster? again I am new to Audi's (but not ignorant to auto mechanics)and I am hoping someone can clue me in as to what it might be .... before I lose 30 day warranty and lose a timing belt or a turbo?

Does the Auditurbo have bearings or a oil receptical?
I know in my old1990 buickPark Ave. supercharged 3.8 it had a tensioner pully and a lube port (really small)that turbo eventually went@ 206,600 mi.and it too sounded like marbles I know a diagnosis is next to impossible without looking at the car but .........suggestions are a jumping off point to protect myself from a huge bill as long as I cantalk to dealer andbe somewhat intelligent as to what I think it might be and not get an argument from him