After my A6 gets warmed up, I get a noise coming from the engine. It SOUNDS like a diesel (kinda drastic description, but the best I can do), but it seems like it's coming from the front of the engine, not within the engine. Could this be a fan noise? Serpentine tensioner? If so, why would the noise start only after the car has warmed up a bit?

 

I have the same issue on my 2.8- here is what "Auditech79" thought it could be-
[ul][*]"If it sounds like a diesel at idle i would first have your oil pressure checked to make sure that is up to par. If thats ok its probably your hydraulic cam adjuster on the passenger's side."[/ul]
After having two shops take a look at both oil pressure and hydraulic cam adjusted they were fine- that lead them to my timing belt pullys which were replaced 20K ago-so I gave them the green light to change timing belt (h20 pum, and all pulls, belt) $1200 later and no change. The pullys for the drive belt (serpentine) tested fine and I replaced my alternator which failed- noise still there. The shop used an electronic stethoscope and they feel it is coming from my values- they want about $900 to replace all 30 on my car- I did not do this as I can't keep dumping $ into at this point. My gas milage is fine, infact everthing runs well except for the noise after the car warms up- they also recommended a thicker oil (Mobil syn 15-50)- so I switchedtemporarily and nothing-

So, if anyone has had this issue with the 4.2 or 2.8 your help is appreciated. Also is there any long term concerns I should be aware of?

 

what about noisy injectors?

 

The shop ruled that out too-the noise appearsafter the engine is warmed up-