Originally Posted by
BigCol
I recognise that tensioner as being the one fitted to the PD engines and would say it is correct.
I've replaced two, one on my old Passat where the pulley had a bit of free play on it, it chattered and did cause a bit of squeal when cold. The other I had done on my current A6 when the cam belt was done as a precaution, however once removed, this to had play on the pulley although it didn't make any noise.
I'd say at 200k it would be wise to replace it. However it would seem that most problems on the aux belt front are caused by the alternator one way clutch. When you have the belt off, check the operation of the alternator pulley, it should run one way and free wheel the other.