I've just noticed this rattle/clicking/ticking sound under the hood when I'm driving during a pull. There's nothing out of the ordinary when sitting at an idle. It's just when the motor is under a load. Today when I got home I put the car in park and held a steady 4500 rpm then 5500. No noise as described while in park. The car doesn't use oil nor does it smoke at all. It's not like an engine knock either. To me is sounds like aluminum foil being pecked on really fast. Yeah I know that's a sad analogy. I've heard it once before about 2 weeks ago. It went away until today. Could it be vibration of some sort? I don't know weather to be concerned or what. Please help
