Weird Squeaking/Scraping Noise

I have an 05 Silverado with the 5.3 (260K Miles) that has developed a weird noise. You hear it most at idle------I think there at higher RPMs but the other sounds mask it.
It sounds like a squeaky fan belt or belt or pulley, but I started it with all the belts off, and its still there. Crawling underneath, it seems to be coming from near the flywheel?? Noise is the same in park or in gear. Noise is there at start up and when hot. Noise went away for about 1000 miles after changing the oil, but them came back.
Truck runs, shifts, and drives great, with no other issues.
Anyone have an idea of what this might be??

I have an 05 Silverado with the 5.3 (260K Miles) that has developed a weird noise. You hear it most at idle------I think there at higher RPMs but the other sounds mask it.
It sounds like a squeaky fan belt or belt or pulley, but I started it with all the belts off, and its still there. Crawling underneath, it seems to be coming from near the flywheel?? Noise is the same in park or in gear. Noise is there at start up and when hot. Noise went away for about 1000 miles after changing the oil, but them came back.
Truck runs, shifts, and drives great, with no other issues.
Anyone have an idea of what this might be??

remove the flywheel cover/starter. inspect for any debris/rocks starter gear/flywheel teeth wear/metal scrap marks etc.

I had a problem with noise here and it was the flywheel cover . had to position it correctly.

Thanks for the ideas, J Cat. I have taken the starter and little inspection cover off, and did not see anything abnormal. No debris. No chips or shavings, and the starter bendix and teeth looked great. The biggest pc pf the puzzle for me is why it went away when I changed oil, and then came back a few miles later??
I am going to try a cheap experiment ----- am going to change oil again and this time put in Synthetic. Let's see if it goes away this time, and for how long??

Thanks for the ideas, J Cat. I have taken the starter and little inspection cover off, and did not see anything abnormal. No debris. No chips or shavings, and the starter bendix and teeth looked great. The biggest pc pf the puzzle for me is why it went away when I changed oil, and then came back a few miles later??
I am going to try a cheap experiment ----- am going to change oil again and this time put in Synthetic. Let's see if it goes away this time, and for how long??

I have been using mobil synthetic 5-30wt. purolator pure one oil filters. so far on all my vehicles all is good. been using this since 1998.

my 5.3L does have the piston slap when its cold out for a few seconds. 2000 silverado. well over 100,ooomi still no oil issues.slap is minimal with synthetic.

the noise could be also the pcv. my PCV did make noises . on later vehicles it is inside the valve cover.

stick a small hose in your ear and probe with the open end for location of noise.

Just a quick update, in case anyone is still listening.
I did change oil and filter, and went with Synthetic. No change---noise was still there after about 1000 miles. So I decided to put in some Justice Bros Oil Additive. Once again, no change in the noise.
Have been poking around on the Internet and found a few posts about bad lifters. Apparently the roller can wear out and/or get pitted and cause a squeak. One guy even posted a uTube Video on the subject --- and the sound in that video is very similar to mine. So I am leaning in that direction, since my engine has 260K on it. Not sure I am going to tear it apart to find-----may just let it squeak and see how long it holds together. It will either get worse, or get better

Just a quick update, in case anyone is still listening.
I did change oil and filter, and went with Synthetic. No change---noise was still there after about 1000 miles. So I decided to put in some Justice Bros Oil Additive. Once again, no change in the noise.
Have been poking around on the Internet and found a few posts about bad lifters. Apparently the roller can wear out and/or get pitted and cause a squeak. One guy even posted a uTube Video on the subject --- and the sound in that video is very similar to mine. So I am leaning in that direction, since my engine has 260K on it. Not sure I am going to tear it apart to find-----may just let it squeak and see how long it holds together. It will either get worse, or get better

I do know that some have had bad valve springs. get a better idea on the source of the sound. use a hose and stick one end in your ear the other probe for noise location.