Does a bad idler pully get louder the faster you drive?

Yes, a failing idler pulley can become louder as you drive faster. The increased speed causes the pulley to spin more rapidly, which can amplify any noise resulting from wear or damage, such as grinding or squeaking. Additionally, the vibration and stress on the pulley at higher speeds can exacerbate these sounds, making them more noticeable. It's essential to address any unusual noises to prevent further damage to the engine's belt system.