My engine is making a scrapping noise at idle. THe sound is loudest if you put a stethoscope on the very front of the valve cover. I replaced my timing chain because i thought it was making the noise. But now im thinking it would be noise coming from where the distributor gear goes together with the cam gear. What do you guys think? Also my truck makes a rattling noise when i start it sometimes. Ive been using a toyota brand oil filter with a anti-drainback valve bc i thought it could be that the tc tensioner didnt have enough oil pressure to operate for a few seconds after starting it. Any help would be great.