Register now to get rid of these ads!

Technical Propane for vacuum leak testing?

Discussion in 'The Hokey Ass Message Board' started by blowby, Sep 11, 2016.

  1. blowby
    Joined: Dec 27, 2012
    Posts: 5,894

    blowby
    Member
    from Nicasio Ca

    Has using an unlit propane torch to test for vacuum leaks ever worked for anyone? What about starting fluid, WD-40, etc.? Is the idea to provide something that will ignite or just temporarily seal the leak?
     
  2. 302GMC
    Joined: Dec 15, 2005
    Posts: 5,643

    302GMC
    Member
    from Idaho

    I prefer starting fluid - it ignites the hair on my arms quicker.
     
    Russco, firstinsteele and blowby like this.
  3. garyf
    Joined: Aug 11, 2006
    Posts: 199

    garyf
    Member

    A Vacuum leak creates a lean condition, spraying carb cleaner at the leak will suck it in a create a rich condition usually smoothing the motor out and increasing idle speed. Propane will work but the engine fan blows the gas around .It isn't sealing the vac leak, its pulling in a vapor or gas that is combustible.
     
    Last edited: Sep 11, 2016
    WDobos likes this.
  4. Jethro
    Joined: Mar 5, 2001
    Posts: 1,401

    Jethro
    ALLIANCE MEMBER

    I seen a guy use an unlit acetylene torch to do this. Worked great for a while until it found an ignition source under the distributor cap. Blew it right off!
     
    1927graham likes this.
    Register now to get rid of these ads!

  5. saltflats
    Joined: Aug 14, 2007
    Posts: 9,442

    saltflats
    Member
    from Missouri

    I have used a lit one to check for freon leaks.
     
  6. putz
    Joined: Jan 22, 2007
    Posts: 515

    putz
    Member
    from wisc.

    starter fluid works good ................
     
  7. tenlug
    Joined: Feb 5, 2006
    Posts: 15

    tenlug
    Member
    from so cal

    Used propane to find a vacuum leak on the intake of a ford fe . Plugged the pcv and ran propane in the valve cover and the idle smoothed out. The part of the gasket had sucked into a port.
     
  8. Right or wrong I use air intake cleaner.
    Haven't started a fire yet.
     
  9. PoRodder
    Joined: Sep 28, 2014
    Posts: 90

    PoRodder
    Member
    from St. Louis

    I've stopped the madness and started using a smoke machine. Instant results.
     
  10. haileyp1014
    Joined: Feb 15, 2006
    Posts: 904

    haileyp1014
    Member
    from so cal

    Seems legit the the expansion rate for propane is only 270:1 good luck
     
  11. Torana68
    Joined: Jan 28, 2008
    Posts: 1,079

    Torana68
    ALLIANCE MEMBER
    from Australia

    I don't like fires or flammable gas floating around, I use oil out of one of those little pump cans.
     
  12. Diavolo
    Joined: Apr 1, 2009
    Posts: 805

    Diavolo
    Member

    Carb cleaner. Just spray it until the rpm changes. It doesn't burn and stuff gets cleaner.
     
  13. 57countrysedan
    Joined: Oct 28, 2012
    Posts: 370

    57countrysedan
    Member
    from NY

    [​IMG] not mine. Internet pic. I use something like this all the time at work looking for vacuum leaks. I think it's more accurate than carb cleaner


    Sent from my iPhone using The H.A.M.B. mobile app
     
  14. Caprice89
    Joined: Dec 30, 2014
    Posts: 163

    Caprice89
    Member

    Brake cleaner does the trick for me.

    Leaking oil? No, sweating horsepower
     
  15. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,085

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Used propane for years.
     
  16. deathrowdave
    Joined: May 27, 2014
    Posts: 1,725

    deathrowdave
    ALLIANCE MEMBER
    from NKy

    Never use brake clean , once it goes through the engine it produces hazardous gas . No so good . You need to remember , propane gas is 1.5x heavier that air so it will collect in the lowest point it can such as garage floor , if water heater or furnace has standing pilot light you could experience a flashing experience


    Sent from my iPhone using The H.A.M.B. mobile app
     
  17. Diavolo
    Joined: Apr 1, 2009
    Posts: 805

    Diavolo
    Member

    This! I try not be all OSHA but using propane instead of non-flammable spray or gasoline to wash parts (which does a terrible job) instead of parts cleaners and degreasers. I just don't know sometimes.
     
  18. Brake cleaner ran thru the combustion chamber can kill or even worse to you or someone else when it comes out of the exhaust pipe. Same killer gas is formed if you spray it on hot exhaust manifolds or weld over some brake cleaner that's been used to clean parts.

    Carb cleaner is the right stuff to use to spray down a running engine looking for vacuum leaks.
     
  19. I can see using it externally to find a leak, but I'm not too crazy about the idea of filling the crankcase with propane. :( Maybe it's just me... o_O
     
    Caprice89 likes this.
  20. aaggie
    Joined: Nov 21, 2009
    Posts: 2,525

    aaggie
    ALLIANCE MEMBER

    Propane is heavier than air so if you took a long time to find the leak it could form a big enough pocket of gas around the engine to explode. People might hear you find the leak for miles around.
     
  21. blowby
    Joined: Dec 27, 2012
    Posts: 5,894

    blowby
    Member
    from Nicasio Ca

    So there is two schools of thought, something combustible or something thick enough to seal the leak for a few seconds. I wonder if just a thick water based solution would work?
     
  22. cshades
    Joined: Sep 2, 2011
    Posts: 438

    cshades
    Member
    from wi

    Smoke machines work the best and are the safest that I know.
     
  23. 302GMC
    Joined: Dec 15, 2005
    Posts: 5,643

    302GMC
    Member
    from Idaho

    ^^^
    Show smoke machine ... old guy not up on current neato tools here.
     
  24. cshades
    Joined: Sep 2, 2011
    Posts: 438

    cshades
    Member
    from wi

    ^^^^ just google evap smoke machine
     
    302GMC likes this.
  25. duncan
    Joined: Aug 23, 2006
    Posts: 977

    duncan
    Member

    Flashing experience? Is that the political correct term for KABOOM these days.


    Sent from my iPhone using The H.A.M.B. mobile app
     
    Caprice89 likes this.
  26. blowby
    Joined: Dec 27, 2012
    Posts: 5,894

    blowby
    Member
    from Nicasio Ca

  27. I use unlit propane. I have found SMALL leaks with propane that were not discovered by spray products. I will also say I always test outside.
     
  28. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,990

    Rusty O'Toole
    Member

    I prefer WD40. It works and is not explosive. To answer OP's question, the idea is to feed something into the leak that will burn. You can tell when you hit the spot because the engine speeds up or smooths out.
     
  29. 1great40
    Joined: Jan 1, 2008
    Posts: 445

    1great40
    Member
    from Walpole MA

    I had a problem where I really couldn't tell if it was the carb cleaner going into the leak or getting sucked into the throat of the carb. That's when I invented the Benjamin Moore vacuum leak tester. I took an old paint can and carved a hole in the lid that fit the air cleaner flange and then ran a large flex hose from the can well away from the engine. When I sprayed the carb cleaner. I was positive that there wasn't any being sucked down the throat of the carb.
     
  30. A neighbor used Propane (I think it was propane, it was that type of torch) on a little Renault many years ago. He had a pretty big vac leak, turned idle way up, and pointed the torch at the base, It stumbled and then went BOOM - blew the carb right off the manifold. Didn't do that again.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.