Air compressor/alternator belt for 1998 Toyota Sienna. There is a bolt in front of the alternator, size 12. Loosen this bolt until you can remove the old belt and replace with a new one. It takes about 15 minutes to do it. Since a new one only cost about $30; replace it with a new one. Once the belt being put in place, tighten the bolt and then you are done. Making sure the belt is not too tight.