strange drumming noise?

[ss]

the car is 2010 audi a4 2.0 tdise technik.with with 40k on the clock
i noticed this strnage drumming noise coming from the engine while it is idling.
is this normal or is it some sort of pump ?
i tried locating the source of thse drumming with a stethoscope but could not hear it where it was coming from.

 

[benjie]

I'm not familiar with this engine, but the older diesels had problems with the bearings in the alternator pulley.

 

[ss]

did alternator bearings cause a drumming sound in the older diesel audis?

(i do know from personal experience that in the older vw 1.9tdis it caused a different sort of sound-(high pitched) when the bearing failed)

 

[benjie]

When mine was on its way out, it was a low rumbling sound when driving and on idle it drummed a little bit, I expect that would have happened more if I didn't replace it as quickly as I did.

 

[Stonefish]

Could be worth using a mobile phone to record the sound and post a short mp3 attachment. There are apps that can record sound or shoot a video and then use software like Microsoft's free Windows Movie Maker to extract the sound file. When my water pump bearing went I posted a sound file and I got some good feedback.