A mechanic's stethoscope is very much like a doctor's stethoscope. Instead of being used to examine a patient's internal noises or breathing, a mechanic's stethoscope is used to listen to and track noises found within an engine. Typically made out of chrome-plated steel, with PVC, or polyvinyl chloride, hoses and rubber ear pieces, it can come in handy for both the professional mechanic as well as the tinkering hobbyist.
Being able to hear engine parts in need of adjustment or replacement, such as grinding ball bearings or a knocking lifter, can help a mechanic isolate problems and repair a vehicle much more efficiently. The interior noises of a motor can be quite difficult to hear using just the human ear alone. The mechanic's stethoscope has sensitive ear pieces that pick up the slightest valve vibration.
Mechanic's stethoscopes can aid in inspecting various car parts, including the transmission, transfer case, valve train, rear axle, and the engine itself. Even problems within the dashboard may be located through utilizing this tool. Worn gears or a water pump failure that may otherwise be challenging to identify can often be located quickly using a stethoscope, making troubleshooting a machine a much easier task.
Tracking down hard-to-find leaks is another function of the mechanic's stethoscope. The tool can actually help a mechanic hear a leak without seeing it, such as in the case of a damaged head gasket. By following the sound of steam, gas, water flow, or oil, problems can be easily isolated, allowing the mechanic to make a timely diagnosis and commence repairs. In this light, the mechanic's stethoscope also proves useful in checking the vacuum and pressure flow of a vehicle — as well as synchronizing multiple carburetors for optimal power and function.
An array of different special ends may be used for various automotive functions. A needle probe, for example, may be utilized to isolate noises that may be difficult to find, as well as seek out smaller, confined areas; while a rubber trumpet can amplify the sound and make it easier to hear. Shorter adapters may be used to inspect broader vehicle areas.
A small tool that takes up little space, a mechanic's stethoscope can disassembled for easy storage and ready use. The handle is typically shock-resistant. Generally an inexpensive tool, there are more expensive varieties that are typically used for teaching purposes.