7 Listen again and complete the conversation. Mechanic 1: I'm still 1 what caused the engine to fail. Mechanic 2: I'm pretty certain that it was an 2 Mechanic 1: Really? I was thinking 3 Mechanic 2: It couldn't be that. The spark plugs are old, but they aren't 4 Mechanic 1: So the sump is cracked? Mechanic 2: The sump 5 Mechanic 1: It isn't? But then 6 an oil leak? Mechanic 2: Look inside the cylinder and tell me what you see. Mechanic 1: The walls are discolored and damaged. It looks really dirty too. Mechanic 2: Exactly. Do you have any idea what caused that? Mechanic 1: My guess is that oil got in there. Ah, so it was the piston rings. Mechanic 2: Exactly. They wore out and oil leaked into the chamber.