My Truck started to have a slight rattle from the front of the engine but would go away after i warmed it up, now it does the all the time. I have a new head and timing chain with about 8,000 miles on them and the block has about 30,000 miles.If i hold a screw diver to my ear it sounds the loudest when i touch it to the front of the valve cover. I can not pinpoint this noise and its driving me crazy. its a 1981 toyota with a 22R.