I replaced the serpentine belt on my van due to normal wear- but the next belt I put on started to seperate long ways and slap under the hood. It didn't do this until 2 weeks after I replaced it- with no noises at all before it happened. I figured it was a bad part- got another one from the same store- put it on- started the engine- made sure it was all in the belt tracks- and 2 weeks later - tap,tap ,tap- the 2nd belt did the same thing- started tearing apart long ways- along the length of the belt. Is there a part that fails and causes this. The original old belt was fine and intact when I changed it- why are the new belts tearing apart ?