Belt tensioner squeak
I have a 2001 SportTrak that has a chipmunk-like squeak worse from 1500 to 2500 rpm. The serpentine tensioner pulley has been replaced 3 times by the dealer, and the belt replaced once. Each time the squeak stopped for a few thousand miles.
Ford installed the same pulley twice, a 'newer style' tensioner pulley once, and claimed that a bad belt was causing problems once.
I know of one other sporttrak with this problem (that belongs to the service managers wife)
Anyone know what the real problem is and how to fix it?