Mechanic's Stethoscope
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
A mechanic's stethoscope is an inexpensive tool for locating noises in engines and other moving parts. It can be used to help diagnose piston slap, worn gears, faulty valves, coolant pump failure, damaged gaskets, defective bearings and body squeaks.