I have a 53 Buick with a 76 Buick 455 engine. I know the basics of engines, but am not a mechanic. I had a leaky gasket on oil filter bracket and took it in to a shop for them to replace it. Long story short, they didn't prime the oil pump after replacing the gasket. I picked the car up and was down the road a quarter mile or so when I noticed it knocking and had no oil pressure. I immediately turned around and went back to the shop. They started it several times trying to figure out the problem. A experience mechanic later figured out that the lessor experience mechanic had forgot to prime the pump after replacing the gasket. They primed the pump and it now has good oil pressure. I went to pick it up and it had a "knocking" sound coming from, what seems to be the front of the engine and was idling semi-rough. I told them I wanted a more experienced mechanic check the car out for damage before I would except it back. My question is: What could have been damaged when engine had no oil pumping for that 1/4 mile? What could the sound most likely be? I don't want them to try to blow smoke up my butt when I go talk to them on Monday. Any advice or information you all could give me would be appreciated.