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How-To: Tracking Down Engine Noises

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  • [All Models] How-To: Tracking Down Engine Noises

    A lot of people ask how what is causing a noise in their engine bay, and that is a big field as engines can make lots of different noises. So I might need to add to this bit by bit, but I'll begin with the most important bit of diagnostic kit in your toolbox - the stethoscope

    Available from (as I've pinched their picture) Sealey VS871 Technician's Stethoscope

    Using a stethoscope allows you to accurately pinpoint the source of noises safely and easily and they are not expensive. This will be one tool you'll use time and time again if you work on cars regularly.

    So why use a stethoscope?

    Firstly you are hearing the noise with both ears, and since both ears are blocked with the earpieces ambient noises are cut down.

    Secondly the tips of the stethoscope allow you to listen to noises without getting your hear, hair or clothing near moving parts. Obviously care is needed, don't go sticking your fingers into a moving belt.

    Thirdly, this particular version offers a metal probe which safely reaches awkward places, and a plastic trumpet which is helpful for tracking down air leaks. The trumpet will amplify localized noises which your ears cannot pick up.

    Different versions at varying prices are available Mechanics Stethoscopes but the one above does everything I usually need.

    Just one example of how it sounds - in this case on fuel injectors 7.3 IDI stethoscope on injectors and lines. - YouTube

    The use is simple. The most usual question asked seems to be valve gear noises - eg sticking lifters. In that case you place the tip of the metal probe to various places on the camshaft cover and you will hear the workings of the engine's internals. By moving the tip you will soon track down the source of the noise.

    This video (Engine noise How to locate and isolate the source - YouTube) has pretty awful sound quality but the first part of it shows the stethoscope in use, and also the alternative - which is a big screwdriver or metal bar. The screwdriver works, but it is less accurate and obviously less safe. It also cannot be used easily on hard to reach places. But for listening to valve gear it works pretty well.
    Last edited by Dave; 09-07-2013, 04:23 PM.
    Originally posted by Vegas
    When I hit boost me fuel runs out