My son has an 02 A6 2.7t. He bought the car with some problems and I fixed everything needed to get it inspected and legal. Right before heading back to college it sprung a leak which turned out to be a cracked thermostat housing. While it was that far apart I we did a water pump and tb. My son watched me take it apart and "helped" by putting things back together to the point of installing the tb. Once it was back together we started the car and it ran fine but a belt was making a terrible racket. I thought it was the serpentine belt but it turned out to be the tb had walked forward and started to shread on the outside edge. The passenger side cam jumped time about a quarter turn. I took it apart again and found the tb idler pulley on backwards and cross threaded. After tapping the block to install the idler properly and reassembling I tried to turn the engine over by hand. It turns almost a quarter turn of the cam and stops. Feels like metal against metal. Is this a bent or broken valve?