:) just trying to help
on my pickup truck 1500 2008 4x4 chevy
so i started to hear a noise every once in a while sounding like bells ringing, very low hard to hear type sound.. well after couple months it's loud that a can hear it. but it was not their all the time, just every once in a while i would hear it. so i check everything in the front of engine. ie axle fluid , shafts for play, nothing seems out of wack ... so time for oil change . tell the mechanic about the noise.
it turned to be catalytic converter exhaust connector rings rusted and when the got hot would make the noise . sounded like muted wind chimes. I was worried it the the fly wheel because that was were it seemed to be coming from..
ps I never went under the truck when it was running or hot to check out the noise.
just sharing my experience with a strange vehicle noise .