If the sound is actually the water pump rather than the tensioner (hard to tell the difference) it would make sort of a buzzing sound.
After R&R belt, pump and tensioner on my '91 100Q 5cyl last December it took to making a whining noise at idle when cold but quit when warmed a bit.
The belt tension is checked like you say with the 90 degree twist but even the it is a mater of how hard it is to twist. Another way I test it to look for about 3/8 to 1/2 inch of flex in the belt between the water pump and the cam pulley.
The bearings in the tenwioner are sealed and do not need greasing.
T>
I just finished replacing a water pump, timing belt and tensioner
> roller on a 4 cylinder 1990 Audi 80. All went well but after less than
> 100 miles the tensioner roller is making a rubbing noise. It is quiet
> when first started but once its warm it makes noise. Do I need to
> lubricate the roller? I paid $50.00 for it from NAPA auto parts so it
> was not a cheap one. Should the roller be lubed with heavy 90 wt oil
> or grease? The belt is not to tight I can turn it 90 degrees no
> problem. I hope I don't have to tear this ?> Thanks for any reply!