A few minutes ago, I dropped off a movie at Blockbuster and left my truck running (it was just across the street from where I parked). When I came back i was listening to the engine and i heard intermittent valve tapping. (tap, tap, tap, tap.............tap, tap, tap, etc). this was the first time i have really stopped to listen to the engine, but this worries me. Especially after that horror story i read that happened to one of the board members here.
Any ideas? Is this normal?