Noise in front of engine 2.6 A6 Avant 1997

[Johan Slump]

There is a noise at the front of the engine which I thought might be a idler/tensioner pully. The car also has a sometimes unstable idling characteristics.When I stopped at a dealer they informed that the noise comes from some control system inside the intake manifold that causes the noise and idling problems. The quote to repair this is also extremely expensive. Anyone with any suggestions to determine the 'real':confused: cause.

[Crasher]

It could be an intake manifold flap, auxiliary belt tensioner, timing belt tensioner (scary) or (with it possibly affecting the idle), a seizing air con compressor. Put the A/C into ECON and see if the problem goes away. I had a 2.5 TDI A4 in a few weeks back where the A/C compressor seized and stopped the engine dead.

[s6sputnik]

It could be an intake manifold flap, auxiliary belt tensioner, timing belt tensioner (scary) or (with it possibly affecting the idle), a seizing air con compressor. Put the A/C into ECON and see if the problem goes away. I had a 2.5 TDI A4 in a few weeks back where the A/C compressor seized and stopped the engine dead.
X2 ...

You better listen very carefully and pinpoint the location of the BAD sound..Rule the above out one by one!