Was told the today that I can use a propane torch to help find a vacuum leak. Was a brief convsersation so I didn't get a lot of info on what exactly to do. I think he said to just turn the gas on, but not light the torch.

Has anybody ever done this, or know what I'm talking about? If so, could you please describe it to me in more detail of what I should be doing? Thanks .

Not a great idea. Try soap and water, WD-40 or some stuff the other guys will suggest.
BOOM!!!!!!!! Ed

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that is the method, no flame with the valve open. done outdoors on a windy day for a short period, should not pose an issue.
Me? I use a stethescope made for finding vacuum leaks, it looks like a normal one, except on the end where the 2 ear tubes Y together, it has about an 8" tube with a smal hole in it;s rounded end. you can hear the hisses pretty clearly with it.
using a 3/8"id hose stuffed in your ear will work too.

torch works pretty good for finding vacuum leaks. With the engine running ust open the valve up so its releaseing the propane and point it at any spots you think there might be a vacuum leak. If there is a vacuum leak there it will suck the propane in and you will hear the engine speed increase.

I wouldn't use soap & water. I wouldn't want even the smallest amount to enter the intake system.

a propane torch works well. You can also use starting fluid/starting ether. Spray it on one hose at a time and the moment you hit the leak, the engine will rev. Let the engine idle between applications as the stuff evaporates quickly. (also don't hover over the engine bay as it's evaporating or you will get a nasty contact high.) Use in a well ventilated area preferably out doors.

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Kendall (Icelander) Whitlatch
'85 Fiero 2M4 - 5spd Isuzu
'67 LeMans/GTO clone 6.5 litre TH400
All the rest aren't Pontiacs, so what does it matter?

quote Originally posted by Icelander: I wouldn't use soap & water. I wouldn't want even the smallest amount to enter the intake system.

Professional mechanics do this by trade on a daily basis.... Whats your basis on thinking its harmful.

Furthermore, i use plain water to clean carbon deposits off of pistons and combustion chambers. use a vacuum source on the intake manifold and suck in little bits of water at a time, it steam cleans the inside of your cylinders. Ever pulled a head that had a head gasket leak and noticed one cylinder was spotless clean because of the burning coolant/water in it? What could possibly be better than steam to clean something with?

So how much soap do you add to the water? What's your ratio? What will an engine accept and how much is considered harmful?

I actually have pulled a head that has blown a head gasket and yes, I have seen how the steam does a wonderful job of cleaning the cylinder. There are systems out there for injecting water into the combustion chamber to cool the engine. I am well aware of uses of water in engine systems.

Have you ever dumped soap in a sink of greasy water? Have you used soap on your hands after working on an engine? Detergent can have a detrimental effect on oil lubricity. That would be my basis on thinking that SOAP and water could be harmful to your engine. I'm also curious what you're supposed to look for when applying soap and water to a leaky vacuume line. Bubbles?

I admit that I could be wrong and that soap and water could be an effective method for detecting leaks. I know it works well on pressurized systems like gas mains but I've seen people wipe straight soap on gas mains connections too. I think it's less effective but some people swear by it. The other solutions offered in this thread also talked about the hazards. This option didn't offer any caveats. What's to stop someone from dumping liquid soap on their engine and causing bearing failure? It's a stretch but I've seen stupider moves made.

The little bit of water you may get wouldnt hurt anything. Old school performance guys used to put water injection on. You put your little bottle of water under the hood and ran a small hose into the intake. Gave you a little more power by cooling the intake mixture. WWII fighter aircraft used the same idea to boost performance.

quote Originally posted by Darkmage: Professional mechanics do this by trade on a daily basis.... Whats your basis on thinking its harmful. Furthermore, i use plain water to clean carbon deposits off of pistons and combustion chambers. use a vacuum source on the intake manifold and suck in little bits of water at a time, it steam cleans the inside of your cylinders. Ever pulled a head that had a head gasket leak and noticed one cylinder was spotless clean because of the burning coolant/water in it? What could possibly be better than steam to clean something with?

Done this before too. Works great, though don't breath too much of the exhaust and don't stand too close to your tips or you'll get junk on you. I saw a TV ad yesterday for a dealership nearby that said a "top engine cleaning" for 175bucks and this is all they do. lol. Anyone want a "Top Engine Cleaning", I'll do it for 100bucks

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1986 Fiero GT - ZZ4 swap and upgraded sus and more in progress
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1986 2m6 (DD#2) Keep mostly stock
2006 (DD) Jeep Wrangler X

IraSummers

the problem with water with detecting vacuum leaks is that is usually gets sucked in too fast with minimal effects on the idle speed, so it is hard to detect.
Starting ether will melt many plastics, so I wouldn;t be spraying that around the engine, not to mention that is much much more likely to flash fire than propane.

There is nothing wrong with using water to clean the motor, It works great on carbon fouled older motors, just realize that you are not going to shove a garden hose in the intake, just use a spray bottle. bit that is not for finding vacuum leaks.

other methods if you have the equipment is to inject smoke into the intake with the motor off and look for where it is seeping out (motor not running obviously). good if you have the equipment other wise....

given a choice I would prefer the propane method over ether. a spray oil would likely work much better than water.
and the stethescope beats them all for speed and precision.

So, if I were to use the propane torch or the spray oil method, what would I look for since the engine idles perfectly fine and the problem is just when in 1st and 2nd gear?

well, then you don;t have a idle problem, wheich is where you will see the majority of vacuum leaks show itself.

what are your symptoms, as much detail as possible. tranny type, only does it warm/cold/all the time etc.... rpm range where it happens etc....

I agree, if your warm ilde close to or under 1k it's not a vacuum leak. Exactly what is doing?

Personally, since i get paid flat rate... (i know its a little dirty) i use carb cleaner a majority of the time, but if its my own personal car, i have a stethoscope that is fairly quick and efficent. Its just in the bottom of my tool box and i usally have a can of carbclean within arms reach. Snap-on makes an electronical tool for finding vacuum leaks that is VERY good... but also VERY pricy... which is why i dont own one... I made my stethoscope from a doctors one, i cut the end off and extended it long and thin, works great....