How to Inspect a Toyota Idler Arm
The idler arm on your Toyota is responsible for maintaining tension on your engine's serpentine belt. The idler arm connects to a spring located directly below the arm. The serpentine belt rides on the idler pulley located on the end of the idler arm. As the belt pulls up on the pulley, the spring pulls down on the idler arm, keeping the belt from slipping. If you have noticed your belt squealing but the belt is new, inspect the idler arm, spring and idler pulley for defect.
- Moderately Easy
- Socket set
Place a 3/8-inch socket driver into the square hole on the idler pulley. Pull up on the ratchet handle to loosen the belt and then pull the belt off the idler pulley.
Let go of the ratchet handle and watch to see if the idler arm pulls downward with any force. If the idler arm does not move downward, inspect the spring below the idler arm. If the idler spring broke loose from the idler arm, the spring is defective. If the spring is still attached and the idler arm moves down with force, move to the next troubleshooting step.
Grab the idler arm with your hand and attempt to pull the arm away from the engine block. If you feel any play, use a socket and ratchet to tighten the bolts that secure the idler arm to the engine block.
Grasp the idler pulley with your hand and see if the bearing is bad inside the idler pulley. Flex the pulley from side to side. If the pulley flexes, the bearing inside the idler pulley is defective. If the pulley does not flex, rotate the pulley and feel if the pulley catches when you rotate it. This indicates a defective bearing. If the pulley spins freely, inspect the pulleys on the other engine accessories for defect as your idler arm, spring and idler pulley function normally.