This thread aims at explaining through photographs and a video of how to change the drive belts on the 3.4 L 5VZ-FE engine. It is easy and I did it with the help of my brother in about 45 minutes. Although I did not replace mine when I took these photos, they should be sufficient to explain how to do it. I will explain in words and you can click on the link to see my video. I have done this 3 times. I am not a master mechanic but I have done some pretty labor intensive repairs including transmissions and timing belts.
Tools you will need:
1) 10 mm, 14 mm and 12 mm wrenches or Gear Wrenches - you don't have to have the geared ones but they are a great help
2) Ratchet and 10 mm, 12 mm and 14 mm sockets with a 3" extension
3) Belts (obviously) Gates or Mitsumi (Toyota Belts) are the best.
4) Coolant (Optional and you will see why)
First I removed the skid plate(s). Since mine is an 02' Sport I had 2 of them. I know that the older models only have one. There are 5 12 mm bolts in the front and if you have the rear, there are 4 12 mm bolts. Next I only loosened the 3 belts:
1) Alternator - I like to undo the alternator belt from the top and below. You can do it from the top but you can't see the adjustment bolt at all underneath. From the top it looks like this:
You loosen the bolt circled in red. It is a 14 mm and allows the alternator to swivel. Now from below (looking up):
You loosen the 12 mm bolt circled in red and loosen the 12 mm adjusting bolt circled in blue. This will swivel your alternator toward the bottom of the truck. Once loose you can now do the A/C belt from below. Hence why you removed your skid plate(s):
You loosen the 14 mm bolt in red and loosen the adjusting bolt in blue (above the front cross member). This is where the gear wrenches are nice. I was not able to get a good area for a ratchet. A gear wrench worked perfectly and I was able to do it quickly. The A/C should be loose now.
Now the PITA: Power Steering. This is the hardest one. Here you can now drain 1/2 gallon or so of coolant or you can choose not to remove the coolant at all. The upper radiator hose will just be in the way if you don't. I didn't remove it the 2nd time I did it and I was glad because I didn't have to refill the radiator. Saved about 15 minutes of time:
Loosen the 14 mm bolts circled in red with a wrench. You can't get a socket in there, if you do you are better than I am because I wasn't able to. The adjustment bolt is underneath to your right of the power steering return line (soft hose higher on the fluid reservoir). I couldn't get a picture of it and you can't see it. If you don't have gear wrenches and only a ratchet it will save you time to remove the air box. You can then use a ratchet. The gear wrench makes it nice because you can get it in there and ratchet the sucker until it comes nice and loose to get the belt off.
Next you will need to unbolt the fan with 4 nuts 10 mm in size with a wrench (again the gear wrenches come in handy here):
Loosen the nuts circled in red. The fan with the silver shaft should separate from the pulleys behind it. Looks can be deceiving here because there are actually 2 pulleys and the fan separated like this:
1 (in red) is the inner pulley with studs that go through the outer pulley (2 in red) and hold the fan on with the shaft for just the fan (3 in red). The blue lines show how they are going to separate.
Now, you can if you wish remove the 4 bolts (2 above and 2 below which are 10 mm) holding the fan shroud on. This allows for movement of the fan so you can slip the belts out between 2 (in red above) and 3 (in red above).
Remove all 3 belts and put new ones on. Installation order: 1: alternator, 2: A/C and 3: Power Steering. The Alternator and power steering belts are similar in length, so make sure you get the right one where it should go or you will end up taking off the belts and putting them on again (like me and my brother). The best thing to do is to put the fan (4 10 mm nuts) and shroud on (if you removed the 4 10 mm bolts) and then tighten the belts, if not you will fight those 2 pulleys that turn the fan.
Rest of installation is reverse order of removal.
Rules of deflection (how much movement up and down in a belt):
If pulley centers are > 6 inches apart: 1/4" to 1/2" deflection between the pulleys
If pulley centers are < 6 inches apart 1/4" deflection between the pulleys
The power steering needs to be about 1/4" deflection, if you don't, then it will squeal when you turn sharply in a parking lot. The alternator needs to be about 1/2" deflection. The A/C needs to be 1/4" deflection.
Video Link (Through YouTube): http://www.youtube.com/watch?v=Y8yF_gD-Mx0