The results from a bad idler pulley from my 1997 Ford Ranger V6 4.0L 4wd / 4x4. One day I went to go start my truck as normal and then all of a sudden I hear this loud squealing sound coming from the engine. So after a close look I realized it was the idler because of the metal shavings coming from the bearings being dry. After a while the pulley seized up and didn't turn at all. Which means the belt was just rubbing against it instead of turning freely. With my truck being 16 years old things like this is expected. The replacement cost of another idler pulley is around $20 - $30. But I went the easy route and just went to my local junk yard and pulled one for $2 bucks.
Signs of a bad Idler Pulley:
- Squealing noise / sound
- Belt breaks (due to pulley seizing up)
- If not the Idler Pulley, Check others.