Squeaks, squeals, rattles, rumbles, and other sounds provide valuable clues about problems and maintenance needs.
Here are some common noises and what they mean:
Squeal — A shrill, sharp noise, usually related to engine speed:
Loose or worn power steering, fan or air conditioning belt.
Click — A slight sharp noise, related to either engine speed or vehicle speed:
Loose wheel cover.
Loose or bent fan blade.
Stuck valve lifter or low engine oil.
Screech — A high-pitched, piercing metallic sound; usually occurs while the vehicle is in motion:
Caused by brake wear indicators to let you know it’s time for maintenance.
Rumble — a low-pitched rhythmic sound.
Defective exhaust pipe, converter or muffler.
Worn universal joint or other drive-line component.
Ping — A high-pitched metallic tapping sound, related to engine speed:
Usually caused by using gas with a lower octane rating than recommended. Check your owner’s manual for the proper octane rating. If the problem persists, engine ignition timing could be at fault.
Heavy Knock — A rhythmic pounding sound:
Worn crankshaft or connecting rod bearings.
Loose transmission torque converter.
Clunk — A random thumping sound:
Loose shock absorber or other suspension component.
Loose exhaust pipe or muffler.
from http://www.consumer.ftc.gov/articles/0211-auto-repair-basics
The more you know about your vehicle, the more likely you’ll be able to head off repair problems. You can detect many common vehicle problems by using your senses: eyeballing the area around your vehicle, listening for strange noises, sensing a difference in the way your vehicle handles, or even noticing unusual odors.