Well,
It would depend on what condition they are in. There is not much to them that can go bad, other than the bearings and the dust seals. If you get them out and find that they spin free, the bearings are not notchy, and that the seals look to be in good condition, then you can most likely re-use them.
There are kits that include the belt, idler pulley, and tensioner all together. About $125 for the set. I'm going to sound like a broken record here, but RockAuto has a Gates kit for that price. They even painted the cast iron housing on the idler pulley assembly, made me smile.
What to watch out for:
The tensioner spring on my engine was out of spec. There is a maximum length spec on that spring, mine was elongated. Dealer has them for $5. This sets the initial tension on the belt, seemed important that it have the factory spec tension before tightening the tensioner bolt.
I just posted a reply in regards to the upper idler assembly, you may need to pull the plenum/throttle body to get that idler assembly off the intake manifold.
If you do remove the plenum, DO NOT DISTURB THE KNOCK SENSOR PIGTAIL. That wire is prone to failure if you monkey with it, just leave the harness assembly on the driver's side alone. Don't look at it, say anything bad about it, treat it with respect. Otherwise, you are going back in and yanking the intake manifold.
Other posts on this site have indicated that it is best to use a factory thermostat. I took that advice, no problems with cooling, small insurance policy.
Do not force the crankshaft timing belt gear back onto the crankshaft, if you take it off. Gently align it to the key to ensure you have correct engagement. If you beat it on, then you probably are not properly engaged on the key and are damaging the gear, key, and crank.
Make sure the washer that goes in front of the crankshaft gear is oriented with the "cupped" face pointing out. The FSM shows this clearly.
Again, do not force the balancer back on, engage it with the key carefully to ensure proper alignment.
And, when torqueing the crank bolt make sure you torque to the specified torque (185 ft-lbs?). On YotaTech.com there are a bunch of posts about this bolt coming loose and then the crank getting destroyed. I put locktite on mine and used the factory 185 ft-lb spec. The 5zfe's have a spec of 217 ft-lbs for the same bolt P/N..... Some uncertainty if that applies to the 3VZE. You will need a special wrench to hold the balancer, or just make one out of a piece of 1/4" thick, x 6" wide x 20" long steel. Hole saw a clearance hole for a socket to get to the crank bolt, drill four holes to bolt it to the balancer. Let it rest on the d-side frame rail when torqueing.
Wow, I write too damn much. I had better get back to work. They are not paying me to post on the internet.
