Even if you cannot diagnose the rattle in your car, it is a good idea to have an idea of what the problem is or to know what you can eliminate as a problem before taking your car into an auto mechanic. If you have a friend who works on his car and has some knowledge, you may want to ask him to listen to the rattle, too.
Eliminate a loose item rattling around your car first such as a pen, small tool or glasses that have fallen out of their case. The rattling sound may be coming from the car trunk or the glove box. If something is loose especially in the glove box or a car compartment, you will hear a rattling sound when you give the car gas or step on the breaks quickly.
Determine if the rattling sound is coming from the front, back or side of your car. Make a note if the rattling sound increases or decreases with the engine RPMs.
Listen closely to figure out if the rattling sound is coming from way up front by the engine or if it is coming from the side of the car where the belts are.
Fix a broken timing chain immediately if you suspect this may be the problem. Not addressing this immediately can lead to serious engine damage.
Figure out what the rattling noise is in your car by using a troubleshooting guide. You can find a number of free troubleshooting guides online, which sometimes prove to be helpful.