I have a 2002 4WD Blazer with 120,000 miles on it. I'm the second owner and it has gotten excellent maintenance.

The problem that I can't solve is: After driving for about 15 minutes it begins a loud chirping from the area of the bellhousing. It's a constant harminic wheather i'm driving or stopped. wheather I increase RPM or idle, in fwd-neut-or reverse, in 4WD or 2WD. I've changed fluids and filters. I've had it on a lift and verified that the sound is coming from the lower end of the drive train.

Any ideas would be greatly appreciated, it's driving me nuts.

 

while it was on the hoist, did anybody drop the torque converter cover, and inspect all of the flex-plate? i came across a very similar situation on my best friend's Dad Astro van.

turned out to be a cracked flex-plate.

you'll probably need to unbolt the TC, and slide it back, so you can properly inspect the flex-plate.