I fitted a new water pump to my '96 300 tdi this afternoon after a bearing collapse a leak and a belt shred : also fitted a new serpentine belt but now it keeps edging off the WP pulley by about two mil, just enough to sit on the flange of the pulley where it make a hell of a noise and it's likely to get shredded. I've tried and tried to get it back in line but after re-starting the engine it waits about five seconds before going off-line again. Could this be a problem with the water pump pulley, power steering pully or the tensioner. The tensioner seemed really taut to move and it was a real tight fit to get the belt back. Prior to this the tensioner was not such a tight fit. Grateful for any advice thanks.