Has anyone used the Harbor Freight stethoscope for finding vacuum leaks? According to the reviews, many people said it worked for that, but from the photo and seeing it in person at the store, it looks like it just has two solid metal probes (one connects to the other) to detect vibration sounds. Not sure if the black bulb in the middle comes apart and the top half of that could be used to hear air sounds ... anyone know?
Does Harbor Freight stethoscope work for finding vacuum leaks?
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rlitman
Well-known member
It does not come apart. You just probe with the metal rod. I own a couple. They're better for detecting mechanical noises than using a screwdriver, but I don't think it would work on a vacuum leak.
Thanks! One reviewer said they changed the design, so I wonder if the other reviewers saying it worked well to find a vacuum leak had an earlier version where you could just use the hollow tube?
rlitman
Well-known member
I've had mine for decades, but it looks just like the picture still. I want to say I paid under $2 for each. It's a great tool for identifying a squeaking idler bearing, but I have a listener that's got a microphone on a gooseneck tube that I hook up to headphones for non-mechanical noises.
As for taking it apart, the rod is in two pieces, and in theory you can bend them for access to difficult places. The rod connects to a diaphragm that is in the equator of that egg. Even if you take the egg apart, I don't think it would work well for open air listening.
Why not buy a cheap Sprague Rappaport Stethoscope? It will come with much more flexible tubing, and can be had for a similar price if you look around.
As for taking it apart, the rod is in two pieces, and in theory you can bend them for access to difficult places. The rod connects to a diaphragm that is in the equator of that egg. Even if you take the egg apart, I don't think it would work well for open air listening.
Why not buy a cheap Sprague Rappaport Stethoscope? It will come with much more flexible tubing, and can be had for a similar price if you look around.
Thanks, will check out the other stethoscope.
rlitman
Well-known member
A Sprague Rappaport is just the run of the mill double headed doctor's scope. You turn the neck to choose the diaphragm or bell (it works like a side-port ball valve).
Expensive ones have a single tube that's divided into two channels inside. Cheap ones have a single tube that's just a single tube. Avoid those and get one that has two tubes.
Expensive ones have a single tube that's divided into two channels inside. Cheap ones have a single tube that's just a single tube. Avoid those and get one that has two tubes.
BolognaBlake
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What are you trying to find a vacuum leak on?
A water bottle, or my libation of choice brake clean, is my go to for automotive vacuum leak detecting.
A water bottle, or my libation of choice brake clean, is my go to for automotive vacuum leak detecting.
Actually, the cover of my chamber vacuum sealer (for sealing food) gets microscopic cracks in it, causing it to lose pressure, and I'd like to use a stethoscope to determine where exactly I have to repair the cracks.
rlitman
Well-known member
What size chamber are we talking about? I don't know if I would try repairing cracks on a pressure vessel like that. It could end up being pretty dangerous.
SGKent
Banned
smoke tester does the best on vacuum leaks. They aren't very expensive. Or you can use a piece of small hose to one ear also. The stethoscope is a solid rod. You need a tube to hear a leak. The solid rod works for mechanical noises. Smoke tester near instantly found a leak in one of our cars I never would have found otherwise. It was in a seal under the back side of the manifold and spray or propane would not have found it easily due to its location. Once I saw the smoke a small mirror and light showed me the location and it was fixed as soon as I got the seal later that day.
2ndGearRubber
Well-known member
Brake clean and a code-reader with short-term fuel trims is the simplest DIY solution south of a smoke machine.
Here's what the food sealer looks like. The clear lid is what gets microscopic cracks in it. Shouldn't be dangerous at all ... I've fixed many other cracks in it using JB Weld Plastic Bonder that were more apparent.
Thanks for the tip. Yeah, I was thinking the solid rod on the stethoscope wouldn't work, so that was the reason for my post.
There are ultrasonic leak detectors that are supposed to pick up noises that you can't hear. I have one of the less expensive ones that I've used a few times with mixed success. The one I have has a transmitter and a receiver and was sold by C. F. Lawrence.
can of carb/throttle body cleaner. Spray the lines while running and when the idle changes from sucking in the cleaner, you've found the leak. Probably won't work for a small leak but cheaper than a smoke machine
I spotted a lower intake gasket leak on my old vortec 350 '96 chevy truck with carb cleaner. Suddenly the miss on that cylinder made sense
I spotted a lower intake gasket leak on my old vortec 350 '96 chevy truck with carb cleaner. Suddenly the miss on that cylinder made sense
I agree on the smoke test, especially if you can use something non-toxic, since you're using it on a food device.
If you're talking about under a hood, I don't know that I love the idea of spraying carb or brake cleaner around, simply because those cleaners can attack paint, rubber, plastic, etc.
Never considered trying to hear a vaccum leak, I must admit.
Mike
If you're talking about under a hood, I don't know that I love the idea of spraying carb or brake cleaner around, simply because those cleaners can attack paint, rubber, plastic, etc.
Never considered trying to hear a vaccum leak, I must admit.
Mike
ChevyEFI
Well-known member
Pressurize it and soapy water bubbles test it.
Several years ago when I was turning wrenches professionally, my cousin that works for Lisle tools gave me a prototype stethoscope that was essentially a cone where the probe would normally be. It worked well for hearing vacuum leaks and such. I'm not sure if it ever made it to production or not.
Another thing that worked great for finding vacuum leaks was a tube on the end of a propane torch. Propane was leaked around the suspect area and an increase in RPM was observed where there was a vacuum leak.
Another thing that worked great for finding vacuum leaks was a tube on the end of a propane torch. Propane was leaked around the suspect area and an increase in RPM was observed where there was a vacuum leak.