How to Remove an Idler Pulley

by Jody L. Campbell

Different engines use different drive belts routed along a pulley system to power the engine components. The main pulley is the crankshaft pulley; most often the lowest pulley in the center. From there, the belt routes the power steering, alternator, air conditioning compressor (if equipped), water pump, automatic belt tensioner (if applicable) and the idler pulley. To remove the idler pulley from a vehicle means the drive belt will need to be removed. Before starting, be sure to have a repair manual for the vehicle you're working on to learn the correct procedure on removing the idler pulley. Another aspect to determine is the location of the drive belt and whether there's enough room to access the idler pulley with the necessary tools to remove it. Some vehicles may require removing a wheel and fender splash guard to access the pulley system on the engine.

Open the hood of the vehicle and locate the drive belt. Look along the front frame rail, under the hood, or the fender rail near the drive belt for the drive belt routing diagram. If it's not present, refer to the repair manual to determine the location of the idler pulley in the pulley system. There's usually only one pulley that does not specifically empower a component for electrical options of the engine, and that's the idler pulley. Do not confuse the idler pulley with the belt tensioner pulley.

Remove the drive belt by relieving the tension on the belt tensioner (if applicable). In some vehicles, lifting it and removing a tire and a fender wheel well splash guard may be required. If a belt tensioner is not present, most likely the tension on the belt is created by the position of the alternator in a slotted bracket. Loosen the bolts on the slotted bracket and manipulate the alternator to release the tension on the belt to remove it. If a belt tensioner is present, it will require a specific-sized wrench, ratchet or tool to release the tension. In most cases, a wrench placed on the bolt at the center of the pulley or a ratchet (with no socket) inserted into a square drive located on the base of the tensioner pulley will be turned clockwise. This motion on the automatic tensioner will allow enough movement in the belt to pull it off of the easiest pulley to access, most often the alternator.

Do not remove the entire belt unless you're replacing the belt. In most cases, you can let the belt dangle from the existing pulleys as long as it is not in the way of accessing the idler pulley.

Locate the idler pulley in the pulley system.

Use a ratchet and a socket or a hand wrench to turn the bolt head located in the center of the idler pulley counterclockwise. Remove the bolt and then remove the pulley.

To replace the idler pulley, reverse the procedure. If a slotted alternator bracket was loosened to relieve tension on the belt, use a pry bar to apply pressure to the position of the alternator, and tighten the bracket bolts. To check the belt for proper tension, you should be able to flip the belt over with the thumb and a forefinger on one hand as it sits on the pulley system and get resistance from the tightness of the belt. If you cannot flip it, the belt is too tight. If you can flip it too easily, the belt is not tight enough.

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About the Author

Jody L. Campbell spent over 15 years as both a manager and an under-car specialist in the automotive repair industry. Prior to that, he managed two different restaurants for over 15 years. Campbell began his professional writing career in 2004 with the publication of his first book.