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  • Engine: Self Loosening Bolts

    Ever since I've owned my 63 Hawk, the rear most exhaust manifold bolt on the passenger side will gradually loosen itself and fall out. This has happened at least a half dozen times in all these years. Has anyone else had this problem, and how do you fix it?

  • #2
    cross drill the head and the one next to it and safty wire it.

    Comment


    • #3
      http://www.musclecarsandclassics.ca/...teel-1965-1967. Or, a french lock can be adapted.
      Bez Auto Alchemy
      573-318-8948
      http://bezautoalchemy.com


      "Don't believe every internet quote" Abe Lincoln

      Comment


      • #4
        How about a little blue Loctite and a jam nut? All threaded fasteners are self-loosening under vibration - they NEVER tighten themselves.
        Gary Ash
        Dartmouth, Mass.

        '32 Indy car replica (in progress)
        ’41 Commander Land Cruiser
        '48 M5
        '65 Wagonaire Commander
        '63 Wagonaire Standard
        web site at http://www.studegarage.com

        Comment


        • #5
          I have a spare engine with a cracked head at that exhaust port. The small crack runs through the threads of the hole. Unless the manifold is removed, the crack is not visible. Someone told me that it's not uncommon. I hope this is not your problem. But it could explain why the bolt keeps coming loose. Even a small crack could decrease "thread contact " and ability to hold torque.
          John Clary
          Greer, SC

          SDC member since 1975

          Comment


          • #6
            Originally posted by bezhawk View Post
            OK, Google got me French Lick (a place, not an action) door locks, window locks, and adding bolt, or fastener did not help. What is a French Lock?
            Ron Dame
            '63 Champ

            Comment


            • #7
              Are you using the inside star lock washers?
              78 Avanti RQB 2792
              64 Avanti R1 R5408
              63 Avanti R1 R4551
              63 Avanti R1 R2281
              62 GT Hawk V15949
              56 GH 6032504
              56 GH 6032588
              55 Speedster 7160047
              55 Speedster 7165279

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              • #8
                Originally posted by ColoradoHawk View Post
                Ever since I've owned my 63 Hawk, the rear most exhaust manifold bolt on the passenger side will gradually loosen itself and fall out. This has happened at least a half dozen times in all these years. Has anyone else had this problem, and how do you fix it?
                Yep, I have noticed the same for decades. Its just another reason to look everything over closely at least upon oil change, every 10,000 miles. I dunno why its usually the rearmost, passenger side bolts, but I too have lost a few along the way. Have often thought of a locking ear, Siamese setup like 56Js have, but never got round to it.

                Comment


                • #9
                  A "French lock" is a metal tab on a washer that can be bent over the bolt head preventing it from turning. Studebaker used them on every engine I can think of. Think of the large crankshaft center bolt. That is a "French Lock"
                  Many manufacturers used them. The link (hopefully) shows a linked french lock that is used on Chevrolet.
                  On .....OH MY...... an EXHAUST MANIFOLD BOLT!!!
                  Here is another link, where it is called exactly that.
                  Last edited by bezhawk; 04-09-2017, 03:31 PM.
                  Bez Auto Alchemy
                  573-318-8948
                  http://bezautoalchemy.com


                  "Don't believe every internet quote" Abe Lincoln

                  Comment


                  • #10
                    Originally posted by bezhawk View Post
                    A "French lock" is a metal tab on a washer that can be bent over the bolt head preventing it from turning. Studebaker used them on every engine I can think of. Think of the large crankshaft center bolt. That is a "French Lock"
                    Many manufacturers used them. The link (hopefully) shows a linked french lock that is used on Chevrolet.
                    On .....OH MY...... an EXHAUST MANIFOLD BOLT!!!
                    Here is another link, where it is called exactly that.
                    http://licorvette.com/french_locks_Corvette.htm
                    Yep. Those are the ones I am talking about. Gotta get some of those for both GTs, one day soon.

                    Comment


                    • #11
                      If that Bolt is stretched, a fresh Grade 8 Bolt will fix it, but use the thick cast Iron Flat washer and outside Star Lock Washer that the Factory used, S.I. may have a barrel full.
                      StudeRich
                      Second Generation Stude Driver,
                      Proud '54 Starliner Owner
                      SDC Member Since 1967

                      Comment


                      • #12
                        Red loctite if it's an exhaust bolt.

                        Comment


                        • #13
                          Thanks. I never heard the term, I just called them locking tabs.

                          Originally posted by bezhawk View Post
                          A "French lock" is a metal tab on a washer that can be bent over the bolt head preventing it from turning. Studebaker used them on every engine I can think of. Think of the large crankshaft center bolt. That is a "French Lock"
                          Many manufacturers used them. The link (hopefully) shows a linked french lock that is used on Chevrolet.
                          On .....OH MY...... an EXHAUST MANIFOLD BOLT!!!
                          Here is another link, where it is called exactly that.
                          http://licorvette.com/french_locks_Corvette.htm
                          Ron Dame
                          '63 Champ

                          Comment


                          • #14
                            You could go to a machine shop and get a .005 oversize bolt made.

                            Comment


                            • #15
                              "All threaded fasteners are self-loosening under vibration - they NEVER tighten themselves."

                              If 90% loosen, and 10% tighten, how would we ever know?

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