Nightmare screeching sound

I have had alot of problems with my isuzu rodeo 1994 3.2 6 cylinder. I've had the timing belt , and tenisor , and water pump changed. I've gone through two alternator, and replaced all of my belts. I am getting a loud screeching sound, second time I had the mechanic put the second alternator on ,the altenator belt came off. My rodeo seems to be loosing power has anyone else ever experience this problem is it possible the belt is to loose again, how tight should it actually be. Please help i am at a stand still. Any suggestions would be appreciated

Thanks.

I just had the water pump, timing belt, tensioner, and all belts and hoses replaced on mine. I had to take it back 4 times to get them to keep tightening the belts because of startup squealing.

does it only happen at start up. does it just happen when it is cold outside?

check the pullys for any grease opr grime that might let the belt slip but not bit down on the pullys

The alternator belt needs to be pretty tight to keep it from slipping. Take it back and have them tighten it.

The problem seems to occur first thing in the morning, or presist when I slow down and idle. I am going to try some of the suggestions here, and if there are anymore please let me know and, I will give and update as soon as possible.

I want to applaud everyone for there help, I find this site to be a very useful tool, and definitely worth the time to do the research to try to resolve problems. Tightning the alternator belt has silienced the humming of birds.

Thanks for everyone help.

By the way stay away from the cheap belts definitely buy the better brand belts it will save you alot of money and time, and heartache.

Thanks again ...