I have a 1994 pontiac sunbird whose timing belt keeps slipping. I had it replaced once, drove it three times, and it wouldn't start. Checked the timing belt which was lose. Turned out the tensioner was worn out. Replaced the timing belt tensioner and timing belt again. Started the car about 4-5 times, got in to take it to be inspected and it wouldn't start. Checked the timing belt. It had been striped. Thought maybe it was just a bad belt. Replaced it a third time. Started great the first 20 times or so and now the same thing is happening. Any suggestions as to why the belt keeps getting damaged?