Pontiac Repair: Alternator belt, correct tension, allignment


Question
NO.  The belt goes around the alternator pully and the waterpump pully. there are seperate belts for the others. thers like 3-4 total belts i cant remember this belt that keeps fallin off is only on the waterpump and alternator and both pump/pully and alternator & pully are replaced and brand new and in correct allignment and correct tension. Its stummped many to as why it keeps throwing the belt off.

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OMG! Im sorry I though I put that its the 2.5l engine!
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There is no tensioner pully in this car. The tension in the belt is created when u set the alternator in place and bolt it down and the belt has the correct tension but is still squeeling we have tried it ALL over and over again! Let me know if u have any other ideas ! Unless we did move the alignment to PERFECT where as it was 1/16" off allignment i think and put the old belt (worn) one on tiill i could get a new one. It fell off and today we put a newone on again! We'll see how it goes maybe it was the allignment! If not ill get back with u or if u knwo anyone else who knows cars that can help! THanks
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OK the ac is fine and its not froze up if you are sepaking of the ac belt! I know its the alternator this means theres nothing else that could be wrong with it huh? Do u think it could be the quality of belt? I keep buying the inexpensive one for the fact it keeps *rolling off* i can tell that because the belt has a *crookedness* to it as if it were runnig on uneven pullys. but its not. should i dish out the $ for the more expensive one? Also its got another problem its over heating while idle. what causes that ? thanks so much!
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I have a 1990 pontiac grand am with almost 50k miles on it. We have a alternator belt that is being *eaten* there is dust all over the inside of the car, It squeels all the time till it decides to *pop* or *slide off* the pullys. I Have replaced the alternator and the pully and the water pump and the pully. The tension on the belt is correct and i have even tried belt conditioner to stop the squeek. The pullys are in perfect allignment so thats no the problem. My dad does the work on my car and its driving him nuts so he sent me to the net for help! Please let me knwo if u can help me!
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Hi, check the A/C make sure that it's not frozed up.
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Hi, have you check the belt tensioner pulley. it can cause this  
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what size is the engine? im guessing here.
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This belt is going around the crank pulley the water pump pulley and the alternator and the power steering?  

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Linda the alternator has a serpentine belt. it gose around the water, now you have the belt that gose around the water pump and power steering pump and crankpulley. this belt will have to be tighting at the power steering pump. put all the belts back on, start the engine let it run for 30sc trun the engine off, look at the belt and see if it is rubbing to the out side or the in side edge of the of the belt. this will tell you if it's out of line or not.