It could be anything from a loose external part vibrating to something wrong internally. Check under the hood physically for loose parts with the engine off. Listen and look under the hood with it at idle to see if it can be narrowed down to an area or component at idle.
June, 7, 2011 AT 2:01 PM
Sometimes when the lifter's become a bit loose from wear, it will make a light ticking or tapping noise that is drowned out when driving (from accelerated RPM's). If it is the lifter's and it is slight/light soundining, I wouldn't worry about it (in my case) but, If it drives you nuts (as it would my wife), I would just have them adjusted at the shop or on your own ONLY if you are mechanically inclined as you can do real damage if not done to specs. I hope this helps.
June, 7, 2011 AT 2:16 PM
Okay, There are no loose parts and the sound appears to be coming from the bottom of the motor not the top. I could be wrong. I will pull the cover off this weekend and check the lifters with a torque wrench.
June, 7, 2011 AT 6:16 PM
If you have a long-ish hose, ratchet extension or a piece of metal rod, start the engine and use it as to help you narrow down where the sound is coming from. Place one end against the valve cover and listen. Place it against the engine block and listen. And place it against the oil pan and listen. This will help you identify where the sound is coming from. Make sure you don't place it against any moving parts and that it is long enough to keep your head away from the engine.