The main purpose of the idler pulley is to create tension and guide the drive belt within the engine. Such belts wrap around engine parts including the alternator, the pump for power steering, and the water pump. If your vehicle’s idler pulley does not function properly, you will end up with quite a frustrating and costly repair unless you take timely action. Let’s take a look at the top signs of a bad idler pulley.

Visual Clues of a Worn Idler Pulley

Every idler pulley ages as time progresses simply because it spins along the belt, creating wear on each part. Such wear decreases tension that can cause significant belt slippage. If the pulley or bearing is noticeably damaged, cracking, breaking, seizing, or otherwise coming apart, it is an indication that it requires prompt replacement. Such damage will prove problematic if it is not addressed in a timely manner as it will prevent the belt from rotating as designed, leading to a slew of additional problems. The last thing you need is for your seized or otherwise broken pulley to cause a torn belt or possibly even lead to the belt completely falling off the engine.

Listen Closely

The idler pulley might make some noise when it starts to go bad. As an example, if you hear the idler pulley or the area of the engine belt squealing, it is an indication the idler pulley might not prove functional for much longer. It is quite possible the engine belt is generating the squealing noise as the idler pulley gradually wears. This noise is created as the engine belt rubs along the idler pulley’s surface. It is important to address this problem in a timely manner as it will only worsen as time progresses.

Observe the Pulley in Action

Take a close look at the belt as it moves across the pulleys. Close observation will help you determine if the pulley has gone bad. It is quite possible the hardware within the pulley has deteriorated. Perhaps there is a hole within the pulley that has expanded, leading to the pulley wobbling or failing to move as smoothly as it should. Furthermore, there is the potential that the pulley has worked itself loose during operation. When in doubt, err on the side of caution by replacing a loose, damaged, or otherwise problematic idler pulley with a brand new one.

A Frozen Idler Pulley Requires Replacement

Bearings within a pulley have the potential to cause it to freeze, making it difficult or even impossible to spin. You can determine if the pulley is stuck or even slightly impeded by manually spinning it. If you find it is difficult to spin the pulley by hand, replace it right away. Be careful when removing the belt from the pulley. The engine should be off and the key should not be in the ignition when you perform this DIY analysis.

Consider the Pulley Bracket

There is a chance the bracket that holds the pulley in position has loosened or become warped. If the supporting bracket is loose or otherwise flawed, the pulley will wobble or possibly even push the belt off the pulley’s path. The pulley is held in position by this mounting bracket that is also connected to the engine. Thankfully, replacing such a bracket is a fairly quick and easy DIY project you can easily do without professional guidance.