[Bob Kontak]

Just get a long 1/2" extension and stick one end in your ear and move the other end around on the engine to isolate the noise. Extra long screwdriver works too. The Freight has cheap stethescopes. Well worth the $6.

Ran into a partially collapsed chain tensioner on a fresh 3.2 rebuild not long ago. It was a strange sound and definitely not correct. Not a ticking like a sloppy valve lash. Not a knock like a rod bearing. Kind/sorta in between. At higher rpm oil pressure would hold the piston up and keep it from damaging the engine. Idle was when the noise would occur.

That said, ear on a socket extension isolated it to the chain box.