I had a new timing belt installed and now it makes noise at between 1000 and 1500 rpm. i had him also install a new water pump. The original serpentine belt was fine even at 78k miles. The tensioner was also fine. this is a 2007 hyundai elantra lim. auto 2 liter. my mechanic previously installed only a belt on my 2001 sonata 2.4 liter auto and it did not make this whrrring sound. It does not happen within the first few minutes then "comes into being" you really don't hear itonce your in the 1600 plus range on rpm's. Car runs and idles fine. I have only 300 miles on the new belt and my mechanic who checked it out said maybe to put another 300-500 miles on the belt and we'll check it again. I have had good work from this guy over the years.