i had the timing belt changed on my car, i had 55k on it when done, 3 weeks and 1k miles later, aka monday night, i start the car up and hear a knocking under the hood, so i check it out, it was a slow knock and it was coming from under the timing cover, so i call the dealer the next morning and get them to check it out since they just replaced it, well apparently the new belt had a defect in it and it had split and a piece of it was slapping the timing cover as it made its rounds....
so in short they warrantied it all, so it cost me nothing and 0 damage was done to the car, but man was i close to a complete fail, but GM would be replacing the motor had it gone bad...
thought i would just share my story with you guys...