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Expansion tank cap finish

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  • John O.
    Very Frequent User
    • May 31, 1998
    • 480

    Expansion tank cap finish

    Can someone tell me what the finish is on the cap for the expansion tank for my 62? I need to get it refinished. Also where can I get a new gasket for it? Or do I have to make my own?

    Thanks....John
  • Joe C.
    Expired
    • August 31, 1999
    • 4598

    #2
    Re: Expansion tank cap finish

    John,

    It should be cadmium plated......nowadays generally done with zinc.

    Joe

    Comment

    • Peter L.
      Extremely Frequent Poster
      • May 31, 1983
      • 1930

      #3
      Re: Expansion tank cap finish

      John - I think you will find that your cap was zinc plated originally. Pete

      Comment

      • Jack H.
        Extremely Frequent Poster
        • April 1, 1990
        • 9906

        #4
        Re: Expansion tank cap finish

        The early rad caps typically used a form of brown fische paper resting against a brass backing plate to form the sealing gasket. Once the paper is shot (and sending the cap out for cad/zinc plating is probably going to take its toll on what paper remains), there's not a LOT you can do.

        To properly replace the paper gasket, you need to remove the rivet that holds the pressure release mechanism to the cap, insert a freshly cut replacement and re-revit the assy together. That's not an impossible job, but one most don't want to deal with.

        The other approach is to hand cut a replacement paper gasket with a LARGE center hole and use a razor blade to cut a fine radial line between the inside and outside circle. Now, you can wrap the paper onto the brass support plate and glue it in place, but you will leave a small telltale parting line.

        Comment

        • Michael H.
          Expired
          • January 29, 2008
          • 7477

          #5
          Re: Expansion tank cap finish

          John,

          A word of caution on your cap, especially if it's an original #307 and you're considering plating the entire cap assembly. I know someone who sent a very nice #307 out for plating. When it came back, it was in several pieces. The acid used in the plating process ate the aluminum center post where it's crimped over and the spring pressure popped the cap apart. The pieces all looked great though.

          Comment

          • John D.
            Extremely Frequent Poster
            • December 1, 1979
            • 5507

            #6
            Re: Expansion tank cap finish

            I once ruined a perfectly good '63 cap many years ago by sending it off for plating. That was a major mistake. Another boo boo was sending off a customers tach cable housing from a '58 to 61 FI car (could have been a '62) and it came back with the aluminum nut eaten away. That cost me bucks as the owner wasn't too happy. Make sure you check the parts with a magnet or that they are brass or you will be an unhappy camper.

            Comment

            • Michael H.
              Expired
              • January 29, 2008
              • 7477

              #7
              Re: Expansion tank cap finish

              Yes, it's a good idea to check/make sure there are no Aluminum components on an assembly that's being plated. The jerk that sent out the #307 that I mentioned above, definitely didn't. (was me, but I wasn't going to admit)

              Comment

              • Peter L.
                Extremely Frequent Poster
                • May 31, 1983
                • 1930

                #8
                Re: Expansion tank cap gasket

                John - Regarding the gasket, are we talking about the fiber one that is 1-5/8" id & 2-1/4" od and fits against the large aluminum spring washer on the underside of the cap and is in contact with the filler neck on the expansion tank when the cap is installed or some other gasket? Pete

                Comment

                • John O.
                  Very Frequent User
                  • May 31, 1998
                  • 480

                  #9
                  Re: Expansion tank cap gasket

                  Hi Pete

                  Yes i'm talking about the gasket that fits in the cap. Does anyone make that gasket or will I have to make one? Thanks to everyone else for your responses.I'll have to check my cap to see whether or not it is aluminum or not before plating it.

                  Thanks again.....John

                  Comment

                  • Peter L.
                    Extremely Frequent Poster
                    • May 31, 1983
                    • 1930

                    #10
                    Re: Expansion tank cap gasket

                    John - If the cap is an AC 307 13lb radiator pressure cap, I would expect the rivet and the large sping washer directly under the cap to be aluminum. Pete

                    Comment

                    • Joe C.
                      Expired
                      • August 31, 1999
                      • 4598

                      #11
                      Re: Expansion tank cap gasket

                      John,

                      Why not give John Pirkle a call. Maybe he can refurbish your cap. If not, he'll fix you up with a replacement.

                      Joe

                      Comment

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