If you want to be a real car doctor, you've got to use the right tools. An automotive stethoscope can be the most effective diagnostic tool in your toolbox. It works just like the ones doctors use, allowing you to “hear inside” a mechanical component. The stethoscope we chose comes with two attachments—a metal probe and a sound amplifier (first photo). Use the amplifier to narrow down the source of the noise. Then switch to the metal probe (second photo) to locate the exact source of the problem.
Connect the amplifier attachment to the hose and move it around the engine compartment. That will narrow your search to a smaller area.