Knocking noise on 01 sr5

[zmmcatee]

My 01 sr5 has developed a knokcing noise when it idles low, like when its in gear and stopped, about 600rpm. It only does it after it has warmed up, the noise is faint and you can feel it slightly in the shifter. I took to the toyota service center and was told that it might be caused by a biuld up in the timing cover area and that it was definitly coming from the lower timing cover area... I was worried that it may have something to do w/ the crank, with 57000 miles on it I need to get it taken care of if it is covered by the warranty. Any input would be great, Thanks, Miles