Oldsmobile/Buick Repair: serpentine belt, crank pulley, crank shaft

Question
i have a 2000 oldsmobile interuige the serpentine belt came offf. i replaced tensour pully and the betl. but the belt keeps coming off

Answer
HI LORENZO,,IF THE BELT IS STILL OFF I WOULD LIKE YOU TO SPIN ALL THE PULLEYS BY HAND,THEY SHOULD SPIN FREELY, THE POWER STEERING WILL HAVE A LITTLE RESISTANCE THIS IS NORMAL...IF ALL OF THIS IS OK,PUT THE BELT ON MAKING SURE THE BELT IS THE CORRECT SIZE,THE WAY TO TELL IS WHEN YOU MOVE THE BELT TENSIONER BACK ALL THE WAY TO GET THE BELT ON THE BELT SHOULD JUST FIT OVER THE LAST PULLEY. IF THE BELT IS REAL LOOSE AND GOES ON THE LAST PULLEY REAL EASY LIKE, THE BELT IS MORE THEN LIKELY TO BIG CAUSING IT TO NOT HAVE ENOUGH TENSION ON IT WHEN GETTING ON THE THROTTLE REAL FAST AND THE BELT MAY COME OFF LIKE THIS..BUT LETS SAY ALL OF THE ABOVE IS GOOD AND THE BELT IS GOOD AND TIGHT..NOW WITH THE BELT ON ALL OF THE PULLEYS I WANT YOU TO STAND IN FRONT OF THE PULLEYS [FRONT OF CAR] AND WITH YOUR EYE LINE THE BELT UP WITH ALL OF THE PULLEYS, MAKING SURE THE BELT IS IN 100% TRUE ALIGNMENT OF ALL THE PULLEYS..USUALLY BELTS COME OF FROM 4 REASONS OUT OF LINE PULLEY,WATER GETS ON THE PULLEYS, A PULLEY LOCKING UP OR BELT IS TO BIG..ON THIS CAR I WANT YOU TO ALSO CK THE CRANK SHAFT PULLEY WHEN IT IS RUNNING AND SEE IF IT IS WOBBLING,IF SO THE RUBBER INSULATOR IS COMING APART. IF SO YOU WILL NEED TO REPLACE THE CRANK PULLEY. IF THE CRANK PULLEY LOOKS IN GOOD SHAPE CK ALL THE OTHER PULLEYS WHILE IT IS RUNNING AS WELL. MAKE SURE THEY SPIN TRUE...NOTE:A SMALL WOBBLE IN A PULLEY IS NOT A PROBLEM..LET ME KNOW HOW THIS GOES AND GOOD LUCK TO YOU,,,TOM..