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  • Gas Tank Rebuild

    A few days ago by son and I could smell gas really strong in the garage. Upon investigating there was gas dripping quite steadily from the tank of Zed. It hasn't even been driven yet this year. I pulled the car out and siphoned it to below the seam to solve the immediate problem. I noticed the last time I had it up on the Hoist that it was wet around the seam and that it always smelled a little bit gassy at the back.
    Yesterday I got brave and pulled the tank out. I tried blowing into the return line to push the last of the fuel out of the feed line and could not get air to flow to do that. The tank with would bulge but no fuel came out. I finally siphoned it out through the gauge opening. When I got the tank out I tried to see why the pickup wouldn't pick up, but it's hidden behind a baffle. I put the air hose on very carefully and managed to blow it clear. I have no idea how the car even ran. Seeing how much dirt and rust there was in the tank was shocking. I had this tank refurbished with urethane coating about 15 years ago, and it has done quite well. I thought about it for a couple of days and finally decided that the only way to really fix this tank is to get inside and knock the dents out, clean it properly and put it back together. I had hoped that because the seam was weeping and opened up that I could put a sharp tool in there and just split it open, but no such luck. I ended up cutting that flange all the way around then grinding it back until it finally snapped open, leaving a little bit of a lip to hopefully weld it back together. As of tonight, I have it all stripped clean with a wire wheel and a coat of POR 15 on the inside up to a couple of inches from the flange, where I will have to weld. I have no idea if this is going to work. I did manage to weld back the fuel line which I accidentally cut off as I was cutting the flange and on the first try I made it airtight. Tomorrow I will clamp the two halves together and attempt to braze the whole seam all the way around. Today I fixed up some pinholes successfully in spite of the metal being as thin as window screen. I was able to flow brass over it and get a tight seal. Just in case, does anyone have a salvageable tank? It wouldn't have to be very good, mine was rusted through all over the place before the gas tank refurbishing place welded patches on it then coated it.
    I'm not sure how good this por-15 is going to be. It looks just like the old oil based aluminum paint that I still have a can of from 40 years ago. It seems awful thin to be filling much of a leak, so I'm hoping to do my weld job well enough that I don't have to rely on it to fill in the seam.
    Attached Files
    Eric Zondervan
    72 240Z
    54 Chevy 3100 pickup
    91 Nissan Figaro
    11 Sierra 4X4
    17 Nissan Juke Nismo
    18 Audi SQ5
    18 Polaris Switchback XCR 800
    17 Yamaha FZ-10
    65 Honda Moped

  • #2
    The POR should last longer than the urethane, but it needs to be fully cured before adding fuel. I think you should be fine though. That's a big job to tackle, nice one.

    Comment


    • #3
      This morning I got it all welded back together. A couple of things I learned. Find and melt out any old solder repairs. Solder and brass mix, but don't stick. Scrape, burn, grind all old coatings off. I had a fire going most of the time and the ashes contaminated my weld. Can't complain though, I filled it with water and had one tiny pinhole in the whole seam, plus a pretty significant leak where there was an old solder patch. I'll block all the exits and put a bit of air pressure on it to expose any more leaks. The por15 would probably seal it at this stage, but I'd like it to be tight before using that stuff. It will make a good secondary seal.
      ​​​
      Attached Files
      Eric Zondervan
      72 240Z
      54 Chevy 3100 pickup
      91 Nissan Figaro
      11 Sierra 4X4
      17 Nissan Juke Nismo
      18 Audi SQ5
      18 Polaris Switchback XCR 800
      17 Yamaha FZ-10
      65 Honda Moped

      Comment


      • #4
        You want to find a leak pour a small amount of rubbing alcohol, methyl hydrate or even paint thinner in, it will find any hole no matter how small.
        Lot of work, so you will have no excuses on July 11th

        Comment


        • #5
          I sealed it all off and put the air hose to it. Air is a lot thinner than water. I found a few more pin holes, but nothing the POR 15 will leak out of. Found out it doesn't take long to burn a hole in an air hose with an acetylene torch.
          I wouldn't want to weld on a tank that just had a flammable liquid in it.
          Last edited by zedfoot; 06-28-2020, 11:29 PM.
          Eric Zondervan
          72 240Z
          54 Chevy 3100 pickup
          91 Nissan Figaro
          11 Sierra 4X4
          17 Nissan Juke Nismo
          18 Audi SQ5
          18 Polaris Switchback XCR 800
          17 Yamaha FZ-10
          65 Honda Moped

          Comment


          • #6
            Ever wonder how your gas gauge is fairly linear when the tank is so odd shaped? Notice how the rheostat is wound much tighter at the bottom half of the range to compensate for the greater volume. The shape of it somewhat mimics the shape of the tank, too.
            Attached Files
            Last edited by zedfoot; 06-28-2020, 11:29 PM.
            Eric Zondervan
            72 240Z
            54 Chevy 3100 pickup
            91 Nissan Figaro
            11 Sierra 4X4
            17 Nissan Juke Nismo
            18 Audi SQ5
            18 Polaris Switchback XCR 800
            17 Yamaha FZ-10
            65 Honda Moped

            Comment


            • #7
              That poor 15 is pretty amazing stuff. It is so thin, it will seep through holes that water didn't come through, but then it starts to set up and will fill quite a good-sized void. Once cured it is extremely tough. I spilled some on a hose clamp, and there was no way of salvaging that clamp. I had to grind It off and use a new one. After letting it cure for a week, I installed it and filled it with gas. I had no leaks, but the engine only ran for a minute and then starved for fuel. It turned out that the POR15 hadblocked the pickup tube. Kind of foolish of me not to have put the air hose on and blown it clear before it cured. I pulled the tank off, thinking I would have to cut a hole in it to get at the pickup tube. After giving it some thought, I attempted to reach through the fuel gauge sender hole and cut the tube off, then yank it out of the tank. It was pretty well buried in por-15 at the bottom of the tank. I put a piece of hose on the stub that was left along with a piece of metal tubing to give it some weight so that it would fall to the bottom of the tank. It was a challenge working through that small hole, but with the right tools I was able to get it on and clamped tight. Now it works like a chainsaw, so I can drive upside down if I want and still get fuel.
              When I got everything back together, the fuel gauge didn't work. I spent a whole morning chasing that gremlin. Finally discovered that the terminal that carries the power is riveted to a brass washer and the brass washer is solered to the resistance wire. Somehow the rivet and the brass washer we're not making contact. With a Dremel tool I was able to grind that clean and dab some solder on it to solve the problem.
              Attached Files
              Last edited by zedfoot; 07-10-2020, 08:19 AM.
              Eric Zondervan
              72 240Z
              54 Chevy 3100 pickup
              91 Nissan Figaro
              11 Sierra 4X4
              17 Nissan Juke Nismo
              18 Audi SQ5
              18 Polaris Switchback XCR 800
              17 Yamaha FZ-10
              65 Honda Moped

              Comment


              • #8
                That's quite the pain, glad you got it figured out. Trying to get hands/tools through that opening must be an exercise in frustration I'd imagine.

                Comment


                • #9
                  Zedfoot, you must have studied proctology to accomplish that repair. I followed your repair with interest because I figured I would have to tackle this kind of repair in the future.

                  Comment


                  • #10
                    In the last photo you can see that the O ring is not seated properly. When I filled the tank last night it leaked. This morning I pulled the unit for the umpteenth time and stretched that O ring as much as I dared. It crept back to its original size pretty quickly, so I had to slap it back together really fast. While I had it out, I bent the float rod so the gauge reads full for the first time in 48 years. The final result is leak free, except for a tiny bit of weeping at the vent hose midway up the tank on the driver's side. I think I used heater hose since 5/8 fuel line is so hard to come by and it has gone rock hard. It's easy to replace, since I put a hard line through the deck long ago.
                    Now I just need somewhere to go for a test drive.
                    Eric Zondervan
                    72 240Z
                    54 Chevy 3100 pickup
                    91 Nissan Figaro
                    11 Sierra 4X4
                    17 Nissan Juke Nismo
                    18 Audi SQ5
                    18 Polaris Switchback XCR 800
                    17 Yamaha FZ-10
                    65 Honda Moped

                    Comment


                    • #11
                      Damn, that's a lot more involved then I would have gotten, splitting the tank like that.

                      Comment


                      • #12
                        Filled it right to the cap and left it in the hot garage for a week. Not the slightest hint of gasoline smell.
                        Eric Zondervan
                        72 240Z
                        54 Chevy 3100 pickup
                        91 Nissan Figaro
                        11 Sierra 4X4
                        17 Nissan Juke Nismo
                        18 Audi SQ5
                        18 Polaris Switchback XCR 800
                        17 Yamaha FZ-10
                        65 Honda Moped

                        Comment


                        • #13
                          Ont240 , http://gastankexchange.com/

                          Comment


                          • #14
                            816FED2D-9FCB-43BC-ABBF-2354B72036FB.jpeg It's the rusty scale and gelled fuel that can cause starvation when it blocks off the pickup tube. Here's evidence.
                            Not my carπŸ’₯
                            Last edited by Ont240; 07-20-2020, 08:26 PM.

                            Comment


                            • #15
                              This winter I'm going to drain the fuel system completely and put a bag of Moisture Grabber in the filler neck.
                              Eric Zondervan
                              72 240Z
                              54 Chevy 3100 pickup
                              91 Nissan Figaro
                              11 Sierra 4X4
                              17 Nissan Juke Nismo
                              18 Audi SQ5
                              18 Polaris Switchback XCR 800
                              17 Yamaha FZ-10
                              65 Honda Moped

                              Comment

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