how to find vacuum leaks ?

[prebordao]

following my stuttering woes i am now looking for vacuum leaks. what's the best way to proceed ?

[azasadny]

Spray carb cleaner around carefully and see when the idle evens out, the place where you sprayed is the location of the vacuum leak. Or, you can do what I did several years ago and replace all the vacuum hoses and clamps at the same time. I got the hoses from our host and the clamps from McMaster-Carr...

[aston@ultrasw.c]

If you have a really hard to find vac leak some shops have a smoke generator that hooks up to the air inlet. The system is pressurised just a few pounds and leaks are shown by smoke trails. In my case it assured me there were no vacuum leaks and I could eliminate that from the search.

[john walker's workshop]

i use oxygen from an oxy/acteylene torch setup. just the oxygen. open the valve to a low flow and run the tip around any suspected leak areas. the idle will speed up if it's sucked in. better than spraying messy aerosols all over.

[stlrj]

I always use carb cleaner liberally over any suspected area. You will not have a mess since it evaporates so quickly, you will never know it was there.

Besides, I don't think that oxygen tanks are very common items in most home garages.

[Joe Bob]

Or Quick Start/Ether...

[rusnak]

I use Ether, but never underestimate the effectiveness of a strong flashlight, an inspection mirror, and your fingertips.

[john walker's workshop]

ether is EXTREMELY flammable. put tape on your eyebrows and wear a hat. shaving is optional.

[47silver]

i put a tennis ball in the exhaust pipe. and connect the outlet of a shop vac to the throttle body with a fitting and clamp.
i bought a bunch of 4th of July smoke bombs. light one and put it on the intake of the vacuum, start the vac, it will suck in the smoke, pressurize the intake system, and you will see the leaks,,
Be patriot and use red , white or blue smoke.

Worked for me, i found out my air box was cracked at the seam.

[cjmurph]

I have seen same results with carb cleaner as with water. Fine mist works well. May depend on the severity of the leak though.

[LM3929]

I took the valve assembly off of an old propane torch and added 6 ft of clear plastic tubing to it with a length of old 1/8" metal brake line tubing on the other end (covered the tubing with shrink tubing to insulate it) and then just run small amounts of propane (in short bursts) and the possible leaks.

Lorne M.

[psalt]

I use an unlit propane torch to find vacuum leaks. Using a gas to find a gas leak is much more effective than using a liquid, and a lot cleaner. My experience is some engine rev up and others stall, depending on the idle mixture and engine management system.

[kach22i]

Using spray water will lower the revs and might make it stall. I have not tried it myself, but sounds like the safest method so far.

[hcoles]

a way that worked for me - use one of those auto stethoscopes - with a long piece of tubing run the end around areas that leaks may be, you will hear a whistling sound when you find the leak.

[jwakil]

Everybody seems to recommend this carb cleaner method, but when I tried it on my SC, I couldn't really use it on the left side of the engine where the air filter inlet is, since it would get sucked in directly to the intake. How do you check the pipes on the inlet side? You really can't spray anything there and get an accurate indication.

[Zeke]

Originally Posted by john walker's workshop

ether is EXTREMELY flammable. put tape on your eyebrows and wear a hat. shaving is optional.

And O2 isn't? The first thing I learned in welding school was that grease or oil and O2 don't mix. Never use grease around your O2 bottle. An oily rag and O2 can be a source for spontaneous combustion and the more O2 the more the flame. Would you like that to be your greasy shirt cuff?

I use WD 40. It's propelled by propane in the spray can version, but the propane is diluted. It will still aid in starting a car if that's all you have, so be careful with any of this stuff.

[Bob Kontak]

Originally Posted by stlrj

Besides, I don't think that oxygen tanks are very common items in most home garages.

BernzOmatic makes an O2 / Mapp gas hose set that combine for a pretty decent blue tip wrench for the home mechanic. You could use the oxygen alone for John's test.

Kind of spendy though when you can get starting fluid for $3.99.

Amazon.com: Specialty Kits: Home Improvement

Edit - After Milt's post I read the recap of the Apollo 1 disaster. Says in there NASA had no idea how fast stuff burns in 100% O2. I am liking the replace all hoses and/or water test more and more. http://en.wikipedia.org/wiki/Apollo_1