My wife's 2002 Subaru Outback (the Legacy body) has approximately 100K miles on the odometer. Under acceleration, I'm hearing a sound like a possible failing belt tensioner. It's a very distinct cyclic high-pitched squeak that isn't apparent under idle.
My intent is to try fine-tuning the tension to see if it's just a hair off but, if that doesn't reduce the squeak, I may have to replace it. What is the procedure for replacing the tensioner pulley?
EDIT: some time later - see the comment on Larry's answer - it was a dying belt, not a bad pulley.