so for the pastweek or two i've been hearing this low ice cube going through a blender/rattle sound that happens after 30 seconds of start up and only at idle. in a way it sound like the chain is hiting the valve cover but its not. i check the chain,tensioner,sparkplugs. end pull the valve cover off to see. everything seem to be intact. it drives me crazy cuz i cant seem to find out where and what it is. i physically check the tct i pulled it out and inspected it. and its fine. i did a valve clearance inspection and i found the exhaust side of cylinder 3 was off. instead of being with in the specs of 0.011-0.013 i could have slide a 0.015 or 0.016 in it. so i adjusted it to be with in corrected spec range. i double check every thing. put the cover back on and still the same thing but this time the sound is diffenetly comming from arround the passenger side mount area. if you place you ear near the mount area it sounlike the chain is rubbing against something off n on. when i raise the rpms to 1100 its consistant with the sound. i pop off the valve cover to check the teeth on the sprokets and theyre all fine. i switch out the tct for a fresh new one and still the same thing. i guess its either the chain has some slack in it or a guide has gone bad. any advice.
down time isnt really and option but if i have to its a must

 

did u check anything that is attached to the belt, like ps, ac, wp, check on k20a.org for more info