Have a 1998 sunfire wont
if it won't hald a charge, a couple of things may be the cause, 1. make sure that the battery is fully charged, have a LOAD test done on it,, just because you get a reading of `12 volts doesn't mean its fully charged in the starting sense,, you need a required amount of amps to actually start a motor, doing a load check on the battery will tell you if you have one or more bad cells in the battery itself, which will make you think that its a charging problem, once you have a known GOOD battery with the correct amps to start the vehicle,, go ahead and start it up,, with a meter, check the battery posts,, ( make sure all connections to the battery are clean and tight ) with the meter in place and the car running you should get a reading of between 13.5-14.5 volts, if you do then the alternator is doing its job, and you should have no more problems, if its not, again, then you have an alternator issue, or as your asking, maybe a belt problem, to address your question, a belt should have just under 1/2 inch of play at the widest section of no contact,,by that I mean,, if the distance between the power steering pump and the alternator has the biggest gap of no pulley contact,, thats where you would check for the 1/2 inch of play , On most newer cars you have an idler arm and a idler pulley that takes up the tension, so if you find that the belt is extremely loose, your problem may be in the idler adjustment, or it could just have a weak or bad return spring