recently got cold weird engine noise need help

it recently got cold here, and i'm hearing a weird clicky clank sound coming out of my value cover on idle.... any ideas?

just started as it got cold, like 30's... tons and tons of rain. I just had a headgasket replaced by the dealership 2k miles ago. so they ripped the valve cover off and it looked fine then.

might maybe a belt not sure its dark. can only hear on idle, barly hear when hood is closed, louder when opend.

sounds like a computer hard drive clicking only louder.

any advice?

update. its light outside now

the circled area is where sound is coming from, NOT the head/vaule cover its the itake manifold, coming from the drivers end of it

i can hear it under car( could be from down there some where)

can't hear when hood is shut, unless you put head under car

car starts (its cold here) 1200 warm up rmps, no sound

car warms up, idles JUST above 500pms, and sound starts

http://img.photobucket.com/albums/v254/treefrog1112/749331_63_full.jpg

Your idle is a bit low when warmed up. Should be around 750-800 rpm. I would guess and say it has something to do with idle if it is idling that low.