97 eclipse spyder manual trans with 102k miles. Car runs fine but I have been noticed an unusual sound.

Basically, when I am in gear and take my foot off the gas peddle, there is a cyclical hum/whine that appears. At first I thought it was just something loose and rattling but when I put the shifter in neutral, the noise stops. The noise also isn't present when the clutch is depressed or I rev it in neutral.

Any ideas what is causing the noise and how to eliminate it?

Thanks

Could be a worn throw out bearing??

thanks but am confused by this article I found on 'throw out bearings':

http://www.carcarecouncil.org/Manual_Transmission/throw-out_bearing.shtml

According to it, "The classic symptom of a worn throw-out bearing is a whirring or growling sound when applying the clutch pedal, which goes away when releasing the pedal".

In my case, it makes a noise when taking my foot off the gas, and not when the clutch is depressed. I feel no difference in the clutch, shifting or when changing gears compared to before the noise started.

Any other thoughts?

Generally when any bearing is going bad, it will "Growl". The whining you are hearing is the wheels driving the gears in the tranny instead of the other way around. I hear it when I am doing about 15-20 and down-shift into 1st when stopping. If the noise is constant it is a different thing altogether. It sounds though that you are hearing something that is totally benign. Most every standard I have ever had I have heard the same nois. And believe me, if it was your throw out bearing you would know it. It can be the most God-awful sound but is ONLY apparent whaen the clutch pedal is depressed.
Ricky

thanks ricky. It's a noise i never heard before, but then again, perhaps i just wasn't looking for it.

Sounds like gear whine to me. There are two sides to a gear tooth, the drive side and the coast side. I'd say the coast side of your gears are worn.