First thing, if your belt seems soft or sloppy when you push on it or if it bounces at an idle. When you start/drive you will get a slight knocking sound between 900-1200 RPM that's the internal spring on the tensioner. To fix this you have to go to a dealer and get the replacement supercharger tensioner. The main tensioner in the back near the firewall is easy to find at auto zone or o'reilly auto parts. The idler pulley is a lot easyer to check. Take your accessory belt off of the idler pulley and try to move it, if theres ANY slop it needs to be replaced.
the pulley is bad when it stops moving
Probably the idler pulley or the tensioner pulley on the serpentine belt. Carefully use a little squirt bottle and spray each one with a little water. When it gets quiet you know which one to change.
The only way to know which style tensioner you have is to remove the crank pulley and timing cover and look.
what's the question? how to do it? specific to corolla or just serpentine belt in general? release tension on belt by: -put a socket/breaker bar or ratched on the tensioner pulley bolt and use it to relieve tension on the belt -slide belt off tensioner pulley. replace with new belt in same pattern across all pulleys and again relieve tension on the tensioner puller to slide the new belt back on --you may need to remove the bolt on the tensioner closest to the pulley (i don't know just judging by the picture i found) ---if you don't know what the tensioner looks like look up the part on autozone's website for a picture you can match on your car
Remove belt and check to see that it rotates freely and smoothly
There is an available bypass kit, but the belt is the same. You remove the ac compressor and install an idler pulley.
Use a "straight edge" to make sure that the "valley" area (where the belt rides) is in alignment with the other pulleys
first you need to be sure you know how the old one is routed, either by the diagram near the radiator or by making your own. there is an "inside" and an "outside" to the belt. next locate the tensioner pulley. its usually attached to the alternator. its the only pulley that isn't attached to/drive anything. put a wrench on the tensioner and slack the belt. remove the old one. compare it to the new one to be certain its the correct replacement. rout the new belt around all the pulleys making sure to insert the belt onto the tensioner last because you will have to slack the tensioner to get the belt on. pay attention to the way the belt "faces" each pulley.
Take it to the dealer! It's not a job for the timid or any shop that doesn't know what they are doing. Make sure you get the idler pulleys and automatic tensioner replace along with the timing belt. If the bearings seize in those idler pulleys it will ruin the belt and in turn take out your engine.
there is not a specific torque for the idler pully. tighten it up with a ratchet and it will not loosen up
Need to know if you have a Detroit, Cat, or Cummins engine in order to answer this. As for the idler pulley itself, it's pretty simple to locate - it's the pulley which only spins, and doesn't actuate a pump, alternator, compressor, etc. Removing it is as simple as loosening the belt, unbolting it, and installing it in the opposite order.
The fan belt that you need will be determined by your make and model and can be had by going to a reputable parts store and just telling them what you are looking for. You probably won't find a belt at Walmart types of places. On this forum you will find information about the belt tensioner pulley and how to change out the belt.....its an easy job but you need a ratchet and a socket of the size that will fit the nut on the front of the tensioner pulley.....you use the ratchet to release the tension on the belt so that you can slip the belt over the tensioner pulley, the last step in the process. Sorry, I don't know what size that socket is but the parts store may. By the way, the tensioner pulley is the only pulley in that mess that doesnt actually drive an engine device (such as the AC, fan, alternator etc). It is spring loaded and keeps the serpentine belt under tension so that all the other things work correctly. This is a job that anyone can easily do but it does help to have someone there to help you: one to push on the ratchet and the other to slip the belt over the tensioner pulley. Good luck