2002 Kia Rio alternator belt constantly squeales.

I would replace the belt, especially if it has been slipping this much. Old belts not only stretch but they get too narrow to contact the pulley correctly so they can get a grip. They also get hot, dry out, harden, and get slippery. Be sure you are installing it with the right tension...not too much or too little. And adjuster bolts have to be tight but don't strip them. I like the cogged belts that can turn sharper on the smaller alternator pulley. There used to be a spray ("belt dressing") that quieted noisy belts. Don't use oil but I once used a tiny, tiny bit of candle wax. It worked. Don't do it with engine running....ouch!

Thanks Hornet, but this is definitely not an old belt issue. The belt that's being used is new (less than 2 months old) and this has been a reoccurring issue for nearly a year now. Originally I would put more tension on the belt and it would stop for about two weeks, only to start squealing again. I checked the engine compartment around the belt and there's belt dust all over the place. Sometimes the belt will get so hot that it starts to smoke. I think I'm going to start with replacing the belt tensioner assembly (keep in mind that this model doesn't have an automatic belt tensioner) and if that doesn't work, then I'll look at replacing pullies until it stops. Other than that, I'm getting rid of this car as soon as I can. If I can fix the problem before I sell it, I'll rest easy that I didn't pass this problem on to the next person.

And of course I will replace the current belt as well.

Thank you tennisshoes. I'm not quite sure what you mean by "full field", but it's certainly worth having the battery checked out. This seems to be a common problem with this particular model from what I've seen from searching the internet, but so far I've yet to have seen a definitive answer, so any suggestion at this point is welcome.

Tennisshoes; I did a little research and I'm posting what I found below: Your question is difficult to answer without you knowing the inner workings of an alternator. The basics. If you move a magnetic field near a coil of wire the electrons in the wire get excited and electricity will be made. The amount of electricity made depends on the size of the magnetic field and its speed. The bigger the field and the faster it's moving the more electricity is made. Also if you have a coil of wire and you pass a current through it it will create a magnetic field. An alternator has 4 basic components; rotor, stator, voltage regulator and bridge rectifier. The rotor is the part that spins. On the rotor there is a coil of wire. By sending a current down that wire a magnetic field is created. Then by spinning the rotor a moving magnetic field is created. Because the rotor is spinning, devices known as slip rings are needed to send uninterrupted current to the rotor. The slip rings are solid brass or copper rings that have stationary spring-loaded carbon brushes riding on them. The voltage regulator controls the system voltage. The voltage regulator sends current to the rotor through the carbon brushes and slip rings. They work in tandem. If the system voltage is low the voltage regulator will send more current to the rotor. If the system voltage is too high the voltage regulator will send less current to the rotor. The stator is the stationary coil of wire that is excited by the spinning magnetic field of the rotor. In reality there are 3 separate coils of wire in the stator separated by 120 degrees. The output of the stator is alternating current (AC). The bridge rectifier then converts the AC into direct current (DC) that the car can use. The whole system is designed to do two things. First, refill the battery after it cranks the engine. Second, supply power to the rest of the car. The way the whole thing works together is that the voltage regulator senses the voltage of the system and adjust the rotor current accordingly. When for example the head lights are flipped on this presents a greater load and lowers the system voltage. The voltage regulator senses this and adjust the rotor current accordingly. Then you go to pass someone on the highway and mash down the gas pedal. This speeds up the engine and the system voltage will go up. The voltage regulator lowers the rotor current to bring the system voltage down. This cat-and-mouse game constantly goes on in the charging system. When an alternator is rated for a particular current output, lets say 100 amps, that rating is at 2000 RPM. The alternator can comfortably make 100A at 2000 RPM. It is designed that way because typical cruise is around 2000 RPM. At idle, the rotor is spinning slower and the alternator is incapable of making it's full rated current. At idle, is when a charging system can get into trouble. A battery is a pig. A battery will take all the current it wants and no less. The current it want is proportional to its state of charge. A discharged or weak battery is very hungry for current. To bring it all together, when a car has a weak battery that battery will want lots of current. The current demand of the battery lowers the system voltage so the voltage regulator compensates by sending more current through the rotor. At idle, the alternator is incapable of making the needed current. Because of this the system voltage drops even more and the voltage regulator sends the maximum current through the rotor. This maximum-load, minimum-speed condition is where the wear happens. At the minimum speed the minimum amount of cooling is available from the built-in fan. At the maximum load the voltage regulator will push the maximum amount of current through the rotor and through the brushes and slip rings. The brushes and slip rings get hot and with no additional cooling available from the fan they will wear faster. If the RPM is increased to above 2000 the situation gets better because more cooling is available and the current through the rotor decreases. This will unfortunately move the wear point from the brushes to the bridge rectifier because now it has to rectify the maximum current. This is preferable, however, as the bridge rectifier is a solid state component and is much less subject to wear.