When this idler wears out it makes a growling noise that changes with engine RPM.
A Bad Idler Pulley May Wobble & Wear Out Your Serpentine Belt Prematurely.
Get Rid Of That Horrible Noise & Change.
Remove the serpentine belt by using a breakover bar, ratcher or serpentine belt removal tool with the correct size socket for the pulley mounting bolt. Rotate tensioner arm to release tension. Remove the bel. Using the proper size socket, remove the tensiones mounting bolt and remove tensioner.
Before installing the new tensioner, make sure the mounting surface for the tensiones is clean and free rust or other obstructions. Find the locator pin hole and rotate the replacement tensiones until the locator pin and the hole line uo. Insert the pin into the hole. Reinstall the mounting bilt and torque down to tight fit.
Rotate the tensioner arm to install the serpentine belt. Make sure the belt is correctly fitted to all pulley in the drive system. Start the engine to check for any problems. Extreme care should be taken when reinstalling the serpentine belt because some of the pulleys are located in remote positions ans it is very hard to see that belt is seated properly in all of the grooves. If the belt isn't seated properly, the belt can "ride out" of the grooves and the belt can be damaged.
Also must review the ZJ Repair Manual Secc-7-Cooling-System
for graphics references.
Hope helped with this. Remember rated this help. Good luck.