Mechanic's Stethoscope
WARNING: This page is about a different car, the 2019 Ford F-550 Super Duty, 2019 Ford F-450 Super Duty, 2019 Ford F-350 Super Duty, and 2019 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
A mechanics stethoscope is an inexpensive tool for locating noises in motors and other moving parts. It can be used to help diagnose worn gears, faulty valves, coolant pump failure, damaged gaskets, defective bearings and body squeaks.