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  • Vacuum Leak Testing ?

    IH All,

    Seems my truck is still running lean and suspect a vacuum leak. Of course everything has checked twice and all hose was new. So what would be the best spray to use to find the vacuum leak while the vehicle is running? Like WD-40 or Stating fluid or brake fluid a product made for this scenario?
    [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

    1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

    1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

    [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
    [B]May be all you need to know about EFI![/B]

    and I still help local JustIH members (for fun) free! :cool: [/CENTER]

  • #2
    I use brake cleaner with the nozzle on it so it can be sprayed where I want it.
    Just listen for a change in RPM or a miss.
    Don't forget the air slot under the manifold. Some manifolds have core plugs in the bottom of them.
    Bill USN-1

    COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
    HAMILTON FUEL INJECTION
    May be the answer to all your fuel injection needs!
    Learn to do it right.

    Comment


    • #3
      its cheaper than you think...

      My dad, an old timer mechanic (they got a lot of DAMN good ideas I never woulda thought of) taught me to use water in a spray bottle to find vacuum, for a few reasons:

      1. Its cheap.
      2. You have an almost limitless supply.
      3. WD-40 and other chemicals are just that - chemicals. Their reactions in the combustion chamber are simply unpredictable. Water will simply cause you to have the miss. its like driving on a rainy day.
      4. Other chemicals can ignite and/or ruin paint on your intake, and are left behind for cleanup. Water will just boil and evaporate.

      Comment


      • #4
        Well I went ahead and used SKuri magical old timers secret (water) in a squirt bottle set to a fine mist. With my truck warmed up I pretty much soaked everything including intake manifold gaskets, vacuum lines to cruise control, vacuum lines to powerbrakes etc... Truck just ran smooth the entire time.

        Hooked up a vacuum gauge and had a steady 17.
        [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

        1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

        1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

        [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
        [B]May be all you need to know about EFI![/B]

        and I still help local JustIH members (for fun) free! :cool: [/CENTER]

        Comment


        • #5
          My only thought on the water is it is heavier than air until it vapors from heat.
          So if you have a vacuum leak on the bottom side of something it has to puddle to be detected.

          The brake cleaner has a very fast evaporation and can be spray just about any where and will be sucked into a vacuum.

          If you removed the aircleaner and sprayed a small mist of water into the TB did it make a noticable change?
          Bill USN-1

          COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
          HAMILTON FUEL INJECTION
          May be the answer to all your fuel injection needs!
          Learn to do it right.

          Comment


          • #6
            When i do it i set it to a coarse spray, not a fine mist, so it shoots a larger amount water. I do notice the miss when i shoot the water, so it should work.

            Comment


            • #7
              If you removed the air-cleaner and sprayed a small mist of water into the TB did it make a noticeable change?
              But I should huh?

              This fine mist was just saturating a whole section at a time. If it were sucking it had to get water. But I will try a squirt down the TB to see and even use brake clean too.
              [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

              1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

              1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

              [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
              [B]May be all you need to know about EFI![/B]

              and I still help local JustIH members (for fun) free! :cool: [/CENTER]

              Comment


              • #8
                If nothing else...water injection really cleans carbon up.
                Helps reduce pinging too.
                Bill USN-1

                COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
                HAMILTON FUEL INJECTION
                May be the answer to all your fuel injection needs!
                Learn to do it right.

                Comment

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