this is from a different thread that i think i posted in the wrong place. i am working on a 97 riviera vin 1 that has a noise coming from the timing cover/block area. i used chassis ear to pinpoint it to the lim bolts under the sc snout. i have changed the chain and gear set, taken the rocker covers off and inspected. nothing was found. the noise is from something internal in engine. when belts are taken off the noise is still there. noise is always there at all temps and rpms but doesn't get worse with mileage. sounds like a metal chirp. wondering if anyone has had a noise from balance shaft. when chain and gears were done spun shaft and checked end play on cam and shaft. also replaced chain tensoiner. i am at a loss at what to do. this is a customers car and has 159000 miles. please help soon. thanks in advance.

Is there any chance of getting a video of this? Might help.

Hmm, both belts off and noise still there. That leaves cam, crank. How does the oil look?

Harmonic Balancer maybe

That could be, I seem to remember there being a rubber spacer between the two parts and it brakes down and rattles.