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Sight Gauges (LDI from McMaster or MSC Industrial)

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  • Sight Gauges (LDI from McMaster or MSC Industrial)

    I ended up going the "Buy" approach for sight gauges, following the guidance from the builder's manuals (old version and the updated guidance at Here's an abridged version of the story:

    What I purchased: McMaster 1106K24 (High-Pressure Oil-Level Indicator, Aluminum, 1/4 NPTF Male, 12" Center-to-Center)
    What I received from McMaster: LDI PN G607-12-A-1-2

    I reached out to LDI with two questions:
    1. Did they have a compatible float ball available. LDI's Answer: Yes - details below
    2. Their website says "Not recommended for use with ... volatile fluids" - why? LDI's Answer: "We don’t recommend use with volatile fluids due to liability."

    LDI has an aluminum float ball available (part number 827830) but sells only through distributors, no direct sales. McMaster agreed to sell a pair to me under PN 1106K999 for $4.90/each. They won't ship them to California (Proposition 65 issue) but I have friends out of state!

    The float balls were easy to install (some disassembly was required) and look good. I'll accept the liability of using these gauges with gasoline - they look plenty sturdy!

  • #2
    Pat Fagan did something similar and it worked out well:



    • #3
      Did you get some assurance that these gages are compatible with aviation fuels. The description is pretty oriented towards use with lubricants. I have found that not all Buta N seals are designed to work gasoline.


      • Dpearson
        Dpearson commented
        Editing a comment
        Not explicitly. I asked LDI if the seals were the reason for their "volatile fluids" website disclaimer, and the only response I got was "We don’t recommend use with volatile fluids due to liability." I'm considering filling a gauge with gasoline and letting it sit for a year or so to see if I notice any seepage. I have plenty of other tasks ahead of me before I will be ready to do the final installation!
        I know Pat Fagan and Russ Erb used these gauges - but I'm not sure if they are active on this forum. Does anyone else have experience (positive or negative) with them?

    • #4
      I would like to know if anyone has used these that will share their experience. They look ideal IF they are fuel compatible.
      Revo Sunglasses Ambassador


      • #5
        I am also planning to use these for my fuel gauges. I've not personally investigated fuel compatibility, but they are called out as an option in the kit builders manual.


        • #6
          I have seen a similar product used on a LSA that was made by Oil-Rite. I think that is the direction I will go too.


          • #7
            After a year with my pvc threaded sight gauges made from aircraft spruce pvc and univair red ball, they went very opaque..barely see red ball. I just replaced them with these..I transfered red ball to these. Just test flew plane with them Installed after my annual. I really like them so far!!


            • #8
              Okay... discussions with Mcmaster and LDI are not working out for finding the floatball compatabile with sight gauge. Part number doesn't exist and cannot offer alternative. Anyone have recent documentation for the item with (possiby) valid part number(s)? Univair does have float balls, but need more info on internal diameter of sight gauge first. Thanks... going back to countersinking now!


              • #9
                I looked at the above options and while they looked good and easy being they are already assembled and a plug and play, I opted to build my own. The reason being if you read the product descriptions they said no fuel. While I figured it would have been ok, I opted to use a clear tube made for fuel. I fly over inhospitable ground the majority of the time and I just do not want any issues with a sight gauge in flight. One post #219 of my “builders log” ( ) you can see my finished product. Only took a few hours to make, the main time spend creating the sight opening in the tubing. I have confidence this will be safe and long lasting. Cost of components was minimal
                Revo Sunglasses Ambassador


                • #10
                  Now to add a question, I have had discussions off the forum about limiting the flow into the sight gauges to stop possible sloshing up and down etc… What methods have you guys used to retard the flows? Did you do it only on the bottom, or both top and bottom?
                  Revo Sunglasses Ambassador


                  • #11
                    I pressed a rivet into the opening and drilled a small hole. It has limited effect. If I did it again I'd perhaps file a small groove along the side of the rivet. It needs to be very small to really limit any flow.
                    Nev Bailey
                    Christchurch, NZ

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                    • #12
                      FWIW, I welded shut the ends of the fuel tubes that connect the sight gauge to the fuel tank and drilled a small hole in the end, top and bottom.

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