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  • Sending Unit Gasket Leaking

    I filled the gas tank on my 61 Hawk when I hauled it home from the body shop recently. When i got home fuel was running down the front of the tank and onto the trailer. That's not good. The car sits to low for me to slide in under it without jacking it up so I grabbed a siphon hose and siphoned out about 5 gallons before it stopped. I got the car off the trailer and into the garage and it was still leaking some. I opened the trunk and took the cover off the sending unit and the gas was leaking out around the screw heads as well as the gasket. The gasket looked like black rubber only made out of some other material. I tried to loosen the screws and make a new gasket but the gas started pouring out. I tightened them back up as much as possible without fear of stripping and it stopped but not 100%. There were 2 wires going to the sending unit. 1 was to the sender and one was added to one of the screw heads as a ground.
    I did some research and found out that there is supposed to be some special copper washers (5) that go under the screw heads to seal the threads from leaking. So I ordered 2 cork gaskets from SI (1 Spare) along with the special copper washers and hopefully this will eliminate the leak issue, which could be devastating. I went ahead and replaced the 3/8 rubber line from the tank to the hard line as it was feeling mushy. I was told by another Studebaker owner that this NEW gas is hard on all the rubber lines, etc. and needs to be periodically replaced.
    The cold weather has hindered me from working on it but wondered if anybody else had this same problem. Also was there 2 wires to the sender unit originally or did someone add the extra one as a safety measure ?

  • #2
    In the past, I have had issues with the black rubber gaskets leaking. I only use the cork now, so you should be in good shape with the ones you ordered.. Not sure what SI is supplying for the copper washers, but the originals we're actually asbestos-filled soft copper 'doughnuts'. Make sure the copper washers you get are somewhat soft; if they are hard, you can consider annealing them (plenty of videos on YouTube on how to a anneal copper).
    Paul
    Winston-Salem, NC
    Visit The Studebaker Skytop Registry website at: www.studebakerskytop.com
    Check out my YouTube channel here: https://www.youtube.com/user/r1lark

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    • #3
      Very common to add an additional ground wire. After many years the unit looses the ground through the tank and the sender quits working properly. Adding that ground wire corrects the problem without searching for the reason the ground was lost, usually corrosion/dirt between the tank and frame/body.
      I usually add a little gas proof sealer to both sides of the cork gasket too when replacing. A dab of sealer in each screw hole prior to inserting the screws is another safety.
      sigpic1966 Daytona (The First One)
      1950 Champion Convertible
      1950 Champion 4Dr
      1955 President 2 Dr Hardtop
      1957 Thunderbird

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      • #4
        Originally posted by r1lark View Post
        In the past, I have had issues with the black rubber gaskets leaking. I only use the cork now, so you should be in good shape with the ones you ordered.. Not sure what SI is supplying for the copper washers, but the originals we're actually asbestos-filled soft copper 'doughnuts'. Make sure the copper washers you get are somewhat soft; if they are hard, you can consider annealing them (plenty of videos on YouTube on how to a anneal copper).
        Asbestos-filled soft copper "doughnuts" ......You hit the nail on the head there . That is exactly what there made of. I suppose the extra ground wire could have been to help the gauge get the signal in case the screws failed to ground and also might help in the event of "Static Electricity". Thanks for your input.

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        • #5
          thunderations,
          what type of sealer did you use ? I know it has to be resistant to gasoline. Also if you placed it on the screw threads when you installed it you might have to have the xtra ground wire in order for the gauge to work.

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          • #6
            Originally posted by Stuhawk View Post
            Asbestos-filled soft copper "doughnuts" ......You hit the nail on the head there . That is exactly what there made of. I suppose the extra ground wire could have been to help the gauge get the signal in case the screws failed to ground and also might help in the event of "Static Electricity". Thanks for your input.
            The actual name for them is annular gaskets, AN900 gaskets, or metal jacketed gaskets. The aircraft industry, for one, uses them. Nowdays they can be filled with asbestos, grafoil, PTFE, or other material. Here are a few links:
            http://www.lamons.com/products/jacke...al-gaskets.php
            http://m.aircraftspruce.com/pages/ha/washers/an900.php
            https://www.google.com/url?sa=t&sour...d_XPdWonY7u-BE

            The last link is to a good .PDF about these gaskets.
            Paul
            Winston-Salem, NC
            Visit The Studebaker Skytop Registry website at: www.studebakerskytop.com
            Check out my YouTube channel here: https://www.youtube.com/user/r1lark

            Comment


            • #7
              r1lark,
              thanks for that info. I downloaded and bookmarked that last link (PDF) after I read it. It told how they are to be installed properly, good to know.
              Thanks

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              • #8
                It was a fuel proof sealant. I looked in the shop to see if I still had it to get a name, but must have used all of it. As I remember it comes as 2 ribbons that need to be blended together and hardens, so may be an epoxy type. Wish I could be of more help. I know if it needs to be removed, the cork will tear and the tank and sender will need to be scraped to clean them up. I always add an extra ground wire as a precaution.
                Originally posted by Stuhawk View Post
                thunderations,
                what type of sealer did you use ? I know it has to be resistant to gasoline. Also if you placed it on the screw threads when you installed it you might have to have the xtra ground wire in order for the gauge to work.
                sigpic1966 Daytona (The First One)
                1950 Champion Convertible
                1950 Champion 4Dr
                1955 President 2 Dr Hardtop
                1957 Thunderbird

                Comment


                • #9
                  For another approach to the gas tank sending unit sealing issue, see issue 070 of the 56J Only Newsletter for my article on the gasket source from Chevs of the '40s and issue 074 for the sealing washers.

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                  Bill L.
                  1962 GT Hawk

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                  • #10
                    Any gasket sealer that is ethanol resistant. I've used this....

                    Click image for larger version

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                    Restorations by Skip Towne

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                    • #11
                      Guys thanks for the info.

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