Earlier this summer I bought a 2003 Hyundai Accent with 130k miles on it. Recently I have noticed a squeaking/squealing sound coming from underneath the hood. I first noticed it at traffic lights, but I have determined that it occurs whenever the clutch pedal is depressed, and continues until the clutch is released.
My first question is - is this serious? (Is it dangerous, or will it compound significantly if I do nothing?) The clutch still seems to work fine, and I can stop the noise at traffic lights etc… by putting the car into neutral and letting off the clutch.
My second question is, how did I cause this? Coasting with the clutch fully depressed, or too much downshifting?
Background: Recently, I bought a Scan Gauge to provide real-time fuel economy feedback, and began to experiment with different driving styles. I found that I could really boost my fuel economy by coasting down longer hills on the highway (when there were no other cars around). To do this I was pressing the clutch all the way to the floor, figuring it was the same as putting the car into neutral. When my speed began to decline after the hill I’d ease back into 5th. One hill in particular comes into town where there is a light. If the light turned red I would stop coasting and do some quick downshifting as well as breaking. I was pretty aggressive with the downshifting on a few occasions.
Did either the downshifting or the coasting likely contribute to my problem? If coasting was an issue, would coasting in neutral cause a similar problem?