Mechanics stethoscopes are exactly what they look and sound like – stethoscopes that are used to track down automotive, mechanical, and other types of machine issues.
Although this sounds vague, many types of mechanical, vacuum, air, other types of problems give rise to a particular noise. Maybe it’s a frictional rubbing, or the hissing as air enters or escapes from a length of tubing. Unusual noises and sounds can sometimes be used to diagnose and locate a problem.
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But here’s the thing – complicated and ordinarily noisy systems, such as an engine bay, can make it difficult to pinpoint where an unusual sound might be coming from. A mechanics stethoscope is one tool that could potentially make troubleshooting easier.
Such stethoscopes typically come with the main earpiece, pre-attached tubing, a horn for amplifying sounds over a broad area, and a longer rod-shaped probe for reaching into tight spaces.
You MUST be cautious when using something like this when there are moving parts.
Stethoscopes won’t always be effective. Other times, they might save you hours of diagnostic work as you work by process of elimination to track down an issue.
Although these are popularly called mechanics stethoscopes, they could be useful beyond automotive and engine diagnostics. Maybe you have a piece of machinery or equipment that emits a squeal or squeak that you cannot locate. Or the sound of friction when all bearings should be buttery-smooth.
I bought a Proto stethoscope a year or two ago, and it has definitely paid for itself by now. I haven’t used it for any automotive work yet, but it has come in very handy in tracking down issues with a failing DC fan, a rubbing shaft in a DC motor application, a linear slide bearing that needed grease in a very tight mechanical assembly, a tiny leak in a 10-foot air hose, and the source of lost vacuum in a small custom-made container.
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Like I said, it’s very useful even beyond automotive applications. If there’s a noise-creating issue, a mechanics stethoscope can help you track it down.
User reviews on Amazon and elsewhere are full of examples of how they can be used in automotive applications.
You can find them for about $20, sometimes less. I would recommend that you buy one that has a funnel-shaped horn and a long probe rod, as both attachments are very useful and complement each other. If I had to buy one again, I’d go with OTC (which looks identical to my Proto set), or Lisle, with Lisle being a more likely first choice.
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If you have used a mechanics stethoscope before, what kind of issues has it helped you troubleshoot or track down?
Hang Fire
I have an old one, so cheap it is not graced with a brand name, picked it up at an auto parts store years ago. Used it to diagnose a bad alternator bearing a few years back, and many times to rule out other issues.
Mine looks exactly like Amazon’s URREA (Mexican Proto) 2342, at $8.23 that’s a good bargain.
Stuart
$8 and change (Amazon LINK) is a low-risk price, but it doesn’t look like there’s a horn attachment.
I can’t really comment on automotive applications, but I’ve used the horn as often as the probe rod, if not more, for other mechanical diagnostic tasks.
fred
I have an old KD Tools 835 that’s probably 45 years old – and may still be sold under the Gearwrench brand. I used it to track down a noise that turned out to be a bad alternator bearing.
Anyway – I’ve seen mechanics use an electronic version – not sure of the brand – but see these on Amazon from Steelman (J.S. Industries) who was the OEM for some Kobalt tools.
http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Dtools&field-keywords=steelman+stethescope
Jimmie
I once used an old nurse’s stethoscope to locate a loose wire nut connection in what turned out to be a hidden junction box behind a bathroom wall. A stethoscope is definitely something worthwhile to have on hand.
Greg
I’ve never known any loose wire nuts make a noise in a junction box unless your specifically pulling on the wire.
Hang Fire
Loose connections can sputter and/or buzz. I’ve corrected a few from a builder’s hurried electrician’s “work”.
Dave L.
In a pinch, you can use a large screwdriver to listen to things like valve trains: Put the tip on the area you want to listen to, then put the end of the handle to your ear. Not quite the same, of course, but if you have nothing else on you…
Stuart
Definitely, DEFINITELY don’t do this around moving components.
Now that you mention it, I’ve heard about this trick before. Never tried it myself.
Brandon
The components probably won’t make ANY noise if they aren’t moving.
Grady
Used a screwdriver to diagnose a dry bearing on a large gear driven vertical boring mill (you could park a small car on the table) back in the late 70s. People called me all kind of names, none of them flattering until the trick proved true and the names changed greatly. Very grateful to the man who taught me the technique.
george
I have one from the 70″s. I used it often and it worked perfectly. eventually I got a fancy electronic one. but I found it limiting and basically went back to the original.
very few noises that it could not find and for sure it was operator error in those instances.
Nathan
mentioned above
valve train issues – IE which lifter was sticking in my neighbor’s 07 chevy 5.3
interior rattles – is it the left front door panel or the left rear door panel – or nope neither it’s the center B pillar panels and seat belt holder.
T
Cheap scopes are the way to go in a pro environment, imo. These types of tools are almost sacrificial at times. It is a simple device that needs little improving if used by a seasoned, well exoerienced individual. I recommend users be less worried about being around moving parts – usually when the offending compnent is making noise thus needing scoped, than blowing an ear drum when the probe shaft gets nicked by a spinning sprocket face or belt – very loud. Ive used electronic ears, wired and wireless, they have their place but a good old $5 generic setho is used 10/1 over the expensive doodads, thus much better return on tool investment. Screwdrivers and long ratches or 1/4 extentions work but are alot less accurate and much more iffy in the safety catagory.
Brian14
My father used one of these a month ago to identify the source of a strange grrrrrrr-ing noise under the hood of my truck. It was the water pump bearing.