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Welding Small Rust Holes in Car Body Panels

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  • Welding Small Rust Holes in Car Body Panels

    I am going to try to fill in some small rust holes in my old 69 Camaro car body. This is in a 20 or 22 ga. material. I am using a Lincoln Pro-MIG 135, .025 L-56 wire. and 75 argon-25 Co2. Can any one give me any tips before I start. I have been practisting on some scrap iron but have yet to get the nerve to start the process. I am doing this alone here and have pulled the car back from a builder who sucked my billfold wrong side out. and do not want to do any damage of my own. Any tips will be very helpful.

  • #2
    First, make sure all the rust is gone.

    What size is 'small'?

    Put a copper plate behind where you're working if you can and start 'tacking' around the edges to fill the hole. go from one side to the other to spread the heat around (this for the larger 'small' holes).


    • #3
      I have the same project coming up in the future with a '68. At one time it had a vinyl top that moisture got under. Thought I had all the rust killed but guess not. All I have is a tig right now, no mig but I am assuming the tig will get it done. What's the best procedure to adding a patch for the big holes?


      • #4
        Probably will not be possible to just fill the holes, since there will be thin, rusty metal around the holes. Best is to look, feel, or peck lightly to determine how far you have to go to get to solid metal. Measure the area, try to make an easy shape (rectangle). Go to your replacement material and cut out the patch. Note - cut the patch first! Then overlay the patch on the bad area, draw outline, and cut out the bad stuff. You want to make it a butt weld with good fit up, so be as exact as possible. If you can put some sort of material behind the butt, it will be easier to weld. Some people make the patch bigger than the hole, and use a tool to form a lap. Another method is to tack in narrow strips of good metal behind the lap, or use copper as one of the other guys suggested.

        After getting good fit up, clean all surfaces as well as possible, all paint and rust needs to be gone. Begin by tacking in place. I lean the gun back slightly and "push" the weld. Start the arc and build a small puddle on the new metal, then move to the seam and old metal. Be careful to "herd" the puddle and let it flow to the old metal rather than leading with the arc and making the puddle follow. This method has the risk of forming a cold weld, but if done properly, lets the old metal fuse with the puddle without burning through. Do small areas at a time, allowing for cooling to prevent warping.

        The problems are burning through the old material and popping from contaminants. No matter how well you clean, the backside of the old metal usually has something on it that can cause problems. When it pops, you lose shielding, the puddle is blown away, and when the arc re establishes it self, it often hits the old metal and burns through.

        I tried to describe the high points, I probably left some things out. Maybe somebody else can add better advice. I find this to be pretty challenging work. Body shops do this all day long, but they are not usually not working with old, rusty bodies.

        If I can do it, anybody can. Be patient. Good luck.
        IDEALARC 250
        HH 135
        Spectrum 375


        • #5
          I had a repair to do a while ago on the panel between the rear window and the boot lid.....I had a lot of little spots of rust that were a couple of mm across scattered across the panel. There had been a trim piece over it for 30 years and small deposits of crap had been trapped under it and rusted through the metal. Only a scatter of small holes, but still a good straight I took my time and filled all these little holes over a period of a few hours.......probably 15 or so holes, small enough to give a quick buzz with the mig and each one was filled. Even though I took my time and the holes were small the panel shrunk all over in an uneven way and now I have a panel that is rust free and no holes, but it isnt nice and straight anymore............I should have filled with fiberglass resin and sand and paint, would have been much easier. The panel was also to good to cut out and fill....anyway i live and learn..........cheers, Pete.


          • #6

            Hey thank you guys alot..... I love this site. This is the first question I have submitted. I just went into town to by a srinking hammer, got back at noon and found several good thoughs and and suggestions. These holes are very small about 1/16" to 1/32" across and about 3/8" long located in the front fender in the bottom corners at bolted a seam between the fender and lower panel. I can see that there is some additional pitting a inch or so away from one. I under stand now to be sure and if I try to just weld these in this may just fall through. At that point if I cant get a good solid area I will need to fix a small patch. I have some other very small pin holes down in a position what sounds kind of like what Bertieboy had. These are under where the back glass use to set. The guy who I had working the car worked these out just by little pecks of weld. I am hoping I can do the same and maybe with a good etching primer help stop the speed of the rusting process.
            This is not a weld subject but has any one heard of these devices that you hook to your car as you keep the car stored, It puts a small electrical charge that they say will stop the electrolite process as the car is attached to this device??? Do they work???

            Thanks again.


            • #7
              Reply cont

              The small areas fixed by the guy who was working the car where under the windshield. They seam to be farely well repaired. I have found out that even though this car was not in real bad shape, its real hard to get all the rust out of an old 60s model car. I have real respect for the guys that rebuild the older cars. I some times wonder if in the 60s that the steel was not as good as that used in the 30s and 40s. I know its not as heavy of gage.


              • #8
                Seems like some particular years of some models were worse rusters than others. I had a 67 SS 350 Camaro in the early 70s that was a serious self destructor, but the later ones like yours don't seem to deteriorate nearly as bad. The 63 Impalas were terrible rusters, the 64s were much better. what's the difference?
                IDEALARC 250
                HH 135
                Spectrum 375


                • #9
                  Ive heard something about that electrical thingy in the past....from what i can remember dont get the wires around the wrong way....otherwise a skeleton might be all thats, In Australia we have some models of fords and holden around the early seventies that have been terrible for rust, then the next years model has been very good rust old bloke told me years ago that old british cars are very good standing up to rust attack......he said the reason why was because they refined the steel better and "boiled" out all the impurities, so when we see a bad model, the metal is to blame......makes sense, anyway, cheers, OZ


                  • #10
                    rust car

                    next time buy a ford!!!!!!!!!!!


                    • #11
                      Carbon Steel Materials

                      Yes Bertie and Robert, My experence with rusting steel The refining is most likely a good statment. I worked for a fabricator, I was over engineering, drafting and materials purchsing. High amounts of carbon naturally cause more rust. Supply and demand come to mind here. GM sells more cars than any other car manufacture in the US. Trying to meet demands and shipment and keeping a line running to maintain supply and demand can very much put pressure on the manufacture and the steel vendors.

                      lhawks, I am not a man of particular requirments. I own Fords and GM autos. And have got long service out of both. All it takes is good maintainance. When I buy, I buy what "I" want. I see on the covers of A lot of ot rod magizines, one being "Popular Hot Rodding" about every third and 2nd issue, a picture of a 1969 Camaro, not a new Mustang. I like what I got and dont pay a premium for parts. If Ford was real smart they would have made more parts compatible with each other, ei. motor/trans. then they would not have to fabricate so many different sub-parts like starters, air cond. compressors, water pumps, generators, alternators and so on. Dont get me wrong. I like both car manufactures. This is just my opinion. Ford has a good rear end, But about everyone puts a small block chevy in their project car.

                      By the way my car is not a so call hot rod, It has a small block, with a four barrel, will 100 in plenty of time. and gets 23 MPG at 65 MPH. Good engineering, Hey.


                      • #12
                        Lets talk welding

                        I am sure now that Hobart would like to see us get back to welding. Thanks a lot Guys for the help. I will be back on the car in the morning trying to do as I was taught here. Thanks again.



                        • #13
                          Re: Welding Small Rust Holes in Car Body Panels

                          Originally posted by RDavis
                          I am going to try to fill in some small rust holes in my old 69 Camaro car body. This is in a 20 or 22 ga. material. I am using a Lincoln Pro-MIG 135, .025 L-56 wire. and 75 argon-25 Co2.
                          My condolences… my friend has one of those Lincolns that I’ve been using more then my own Hobart lately and I HATE the thing. It would be a good welder if you replaced the wire feed with the Hobart/miller unit. Play with one of each and you’ll see what I’m talking about, the Lincoln likes to skip/slip every once in a while which is enough to put an ugly part in a weld in something thicker and a hole in something thinner. Keep the drive really clean in them and it will be OK, we finally figured out something by filing down part of the frame for the drive that allowed the rollers to properly adjust (the way they come from the factory you can’t get the tension right .025” wire, I’ve used 3 or 4 now and they’re all the same).

                          Can any one give me any tips before I start. I have been practisting on some scrap iron but have yet to get the nerve to start the process. I am doing this alone here and have pulled the car back from a builder who sucked my billfold wrong side out. and do not want to do any damage of my own. Any tips will be very helpful.
                          Bodyshop jail sucks…

                          I’d be really surprised if your rust is so isolated that you could get away with just zipping the pinholes shut… usually pinholes result from a wider area of rust on the front or the back which if you don’t get rid of will be back in less then a year.

                          As far as successful welding on that light stuff… keep the gun back as far as you can go and still get a good shield (usually in the ½-5/8” range). Leaning the gun back some against the panel will help also, so you’re aiming into the good section of the panel.

                          If possible after your done try to make sure that you have both sides well prepped, cleaned up and treated with some kind of rust inhibitor or you will get the rust back. You may want to look for a product line called Picklex, most people consider it superior to the better known Por 15 line. I’ve also gotten away with using the rustolium spray galvanizing primer (even though it’s not recommended for this kind of application), that stuff seems to put rust at bay better then anything else that I’ve tried that I can get at the corner hardware store.
                          (aka: Silverback, WS6 TA, JYDog, 83 Crossfire TA, mpikas, mmp...)
                          Bridgeport J-head -- Synchrowave 180 SD -- Hobart Handler 135 -- HTP 38 plasma
                          HF bandsaw -- Rigid 4.5” angle grinder (+2 cheapie HF ones)


                          • #14
                            i suggest going to the local body shop and buying a product called "panel bond". it is actually stonger then a weld and will not corrode and fall out like bondo.


                            • #15
                              Re: rust car

                              Originally posted by lhawks
                              next time buy a ford!!!!!!!!!!!
                              your joking right