jazzvette

I bought a 2000 coupe about three weeks ago,it had 34,000 miles on it from the original owner with all the records.The car was dealer maintained from day one.I love the car but I have one small problem with it.The harmonic balancer is wobbling slightly and the belts I guess is making that chirping noise .I had the main belt taken off and the pullies pressure washed.The owner took the car in to the dealer just before I bought it and had the tensioners and belts replaced.When I left Miami it was quiet but by the time I got to Jacksonville the noise returned.
It kind of sounds like the water pump to me.As far as the harmonic balancer goes it was replaced in 2003.I've read on the forum that the GM units sometimes wobble on the C5.Need help with this issue.

Threed

Most likely it is the balancer. It shouldn't be wobbeling. It is a common problem.

Bob25thTA

Check the Air Cond idler pulley and tensioner pulley. My idler pulley bearing was worn and causing a squeak, it was rubbing against the inner spacer/washer. About $15 replacement cost and easy to do.

LoneStarFRC

Despite the fact that you say the pulleys were pressure washed, if there is any dirt and/or sand particles lodged in the grooves, they need to be wire brushed out. Wire brush them all the way around.
The idler pulleys can be a source of noise on some vehicles too. BTW, they are much less expensive than the tensioners. One last thing; dump the OEM belts and go with Goodyear Gatorbacks.