Quote Originally Posted by oj88 View Post
The main symptom of a bad release bearing is if the noise is heard while the clutch pedal is released (clutch plate is engaged). I think the OP experienced the opposite problem, in that, the noise only happens when the clutch pedal is depressed (clutch plate is disengaged).

While the clutch pedal is depressed, the release bearing is not rotating with the engine, so I think it's unlikely that the release bearing is causing the noise.
When you depress the clutch, the bearing should actually spin together with the center of the pressure plate. If it is worn out and does not spin properly, it wears out the diaphragm spring in the center of the pressure plate.

Here's a description from "How Stuff Works":

"Another problem associated with clutches is a worn throw-out bearing, sometimes called a clutch release bearing. This bearing applies force to the fingers of the spinning pressure plate to release the clutch. If you hear a rumbling sound when the clutch engages, you might have a problem with the throw-out.


[SIZE=+1]Clutch Diagnostic Test[/SIZE]
[SIZE=-1]If you find that your clutch has failed, here is an at-home diagnostic test that anyone can perform:[/SIZE]
  1. [SIZE=2]Start your car, set the parking break, and put the car in neutral. [/SIZE]
  2. [SIZE=2]With your car idling, listen for a growling noise without pushing the clutch in. If you hear something, it's most likely a problem with the transmission. If you don't hear a noise, proceed to step three.[/SIZE]
  3. [SIZE=2]With the car still in neutral, begin to push the clutch and listen for noise. If you hear a chirping noise as you press, it's most likely the clutch release, or throw-out bearing. If you don't hear a noise, proceed to step four.[/SIZE]
  4. [SIZE=2]Push the clutch all the way to the floor. If you hear a squealing noise, it's probably the pilot bearing or bushing.[/SIZE]
[SIZE=2]If you don't hear any noise during these four steps, then your problem is probably not the clutch. If you hear the noise at idle and it goes away when the clutch is pressed, it may be an issue in the contact point between the fork and pivot ball.[/SIZE]