R&R of fuel filler neck gasket - NCRS Discussion Boards

R&R of fuel filler neck gasket

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  • Jeff S.
    Very Frequent User
    • July 31, 1984
    • 384

    R&R of fuel filler neck gasket

    One of my winter chores is to replace the filler neck cork gasket (3826417) on my '66 convertible. I have a set of the special machine screws w/sealing washer (3767804), but have not purchased the gasket yet. Couple questions follow:

    Can this task be done by accessing everything through the 'hole' once opened up by removing the fuel cap cover, bezel, & rubber seal ... or will I have to lower the tank to work from below?

    Are the repro cork gaskets sold by the 'usual suspects' of sufficient quality & fit? Can't seem to locate an NOS GM part.

    Should I use a two repro gasket stack? Seems like I read somewhere that the mating flanges are not known for having good surface finish or parallelism.

    Is any Permatex or similar sealant used? If so, on one or both of the cork's surface(s)?

    Thanks in advance
    Jeff
  • Jim T.
    Expired
    • March 1, 1993
    • 5351

    #2
    Re: R&R of fuel filler neck gasket

    I have replaced the gasket on my original owner 1970. It was a cork gasket when I purchased it from my local Chevrolet parts counter. I have also replaced the gaskets on my 1985 and 1996 Corvettes, the gasket is not cork. The torque on the attaching bolts is in low inch pounds. The gaskets are different for the C4's and C3's. The torque for the C4's is in the service manuals which I do not have access to right now. I did not lower the fuel tank on my 1970, 1985, or 1996. No sealant was used. Just remove the fuel cap cover/bezel and rubber seal around the outside neck.
    Last edited by Jim T.; December 22, 2015, 06:56 PM.

    Comment

    • Joe L.
      Beyond Control Poster
      • February 1, 1988
      • 43221

      #3
      Re: R&R of fuel filler neck gasket

      Originally posted by Jeff Smith (7732)
      One of my winter chores is to replace the filler neck cork gasket (3826417) on my '66 convertible. I have a set of the special machine screws w/sealing washer (3767804), but have not purchased the gasket yet. Couple questions follow:

      Can this task be done by accessing everything through the 'hole' once opened up by removing the fuel cap cover, bezel, & rubber seal ... or will I have to lower the tank to work from below?

      Are the repro cork gaskets sold by the 'usual suspects' of sufficient quality & fit? Can't seem to locate an NOS GM part.

      Should I use a two repro gasket stack? Seems like I read somewhere that the mating flanges are not known for having good surface finish or parallelism.

      Is any Permatex or similar sealant used? If so, on one or both of the cork's surface(s)?

      Thanks in advance
      Jeff

      Jeff-------



      The job can be done through the filler opening.

      The repro gaskets are as good as original GM. However, I don't like the cork gaskets for the filler neck. I make a gasket out of a sheet of buna-N rubber.

      You may need to straighten the flange of the filler neck. The flange gets "pulled down" in the area of the screws, just like oil pans and timing covers. The flange can be repaired in the same manner as oil pans and timing covers.

      No sealer is required.
      In Appreciation of John Hinckley

      Comment

      • Mike M.
        NCRS Past President
        • May 31, 1974
        • 8383

        #4
        Re: R&R of fuel filler neck gasket

        the job can be accomplished thru the opening in the rear top surround IFF all of the fasteners come out without breaking( in which case i'd remove the tank to remove the broken threads in the tank) . those small fasteners commonly break when attempting to remove them from the tank. perhaps soaking them with a penetrant would help. mike

        Comment

        • Frank D.
          Expired
          • December 27, 2007
          • 2703

          #5
          Re: R&R of fuel filler neck gasket

          Those fasteners are small but sit on a rubber O-ring if original; they should come loose OK unless somebody torqued the snot out of them.

          A simple one hour job - just did it on my '63 coupe. I used two cork gaskets because the flange was somewhat wavy.....be sure to buy NEW hex nuts to go around the gasket - they have a rubber O-ring on them for sealing - I'm sure your old ones are shot. I stuffed something in the gas tank to prevent bits falling in there while working - can't remember what just now. I think it was a properly sized funnel with the end taped off.

          This is a good time to buy a new one of those toilet plunger rubber neck surrounds if yours is dicey and make sure your overfill nipple and drain hose are all situated properly.
          Attached Files
          Last edited by Frank D.; December 23, 2015, 11:12 AM.

          Comment

          • David Z.
            Very Frequent User
            • April 1, 2002
            • 181

            #6
            Re: R&R of fuel filler neck gasket

            As Joe, Frank and others have pointed out above, the job is pretty straightforward and is done through the filler opening. If I recall, this was the first job I did when we got our '65 in 2001. Fuel at my feet was the telltale that something was amiss the first time I filled it up to the bottom of the filler neck. Ugh.

            I put together a brief "how to" on the job that may be of use to any who are contemplating changing the filler neck gasket or other components of the filler area. A PDF is attached.

            Dave Z
            Attached Files
            Dave Zuberer

            Comment

            • Jeff S.
              Very Frequent User
              • July 31, 1984
              • 384

              #7
              Re: R&R of fuel filler neck gasket

              Joe - do you happen to recall the thickness of the buna-N sheet you used to fabricate gasket? Thanks.

              Comment

              • Joe L.
                Beyond Control Poster
                • February 1, 1988
                • 43221

                #8
                Re: R&R of fuel filler neck gasket

                Originally posted by Jeff Smith (7732)
                Joe - do you happen to recall the thickness of the buna-N sheet you used to fabricate gasket? Thanks.

                Jeff-----


                My recollection is that it was about 3/32" to 1/8" thick. I think I still have some of the sheet around here. IF (big IF) I can find it, I'll confirm.
                In Appreciation of John Hinckley

                Comment

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