The best way for me to hear this sound is when I pull into my driveway which has a wall on one side and the sound resonates. The best way I can describe it is a pressure cooker like sound. I tried pinpointing it, however, I was only able to make a generalization of where the sound was coming from. Sound comes from the alternator/timing area. Only heard during idle.

Youtube

very vague video. proping the hood wud help