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Impressed current cathodic protection in automotive

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  • Impressed current cathodic protection in automotive

    I have been working on a 1988 ford bronco to hopefully replace my '99 p/u as my daily driver and tow rig. I live smack in the middle of a state that thinks road salt should flow like honey... Needless to say, this truck is riddled with rust. I have replaced the frame w/ drivetrain and running gear from a much newer F350. Anyhow, I have been spending most of my free time cutting out the rusted areas of the panels, and replacing them with new sheet metal.

    We all know the purpose of the original galvanization is to act as a sacrificial anode and help delay the corrosion of the steel. There is a plethora of coating products on the market that claim that they are able to stop, and prevent further rust. One that looks very promising, and which I had heard good things about, is rustbullet. I intend to give this a shot on the areas that are just not feasible to cut out and replace. Like the bottom of the tub for instance.

    Anyhow, I got thinking about setting up an impressed current setup to help further my chances of the vehicle surviving. The petroleum and chemical industries use these systems extensively to protect storage tanks and pipelines. A bit of research, however, turned up a lot of companies already offering a turn key setup. More research suggested that the idea does not work in an automotive environment, due to the fact that there is not a constant submersion in electrolyte, and that the folks marketing the products are just get rich quick scam artists.

    I can see where a simple sacrificial anode setup would not work, unless all steel surfaces were coated (galvanized) w/o the electrolyte, but I am having trouble understanding why it would not work with an impressed current system. I know there are some geniuses on here, so I thought I would ask. Is there a chance in hades that this would actually help? Especially in a humid, salt rich environment like Michigan in the winter?


  • #2
    Jason, I worked a few yrs. as a corrosion tech on crude oil piplines and storage tanks. I think you answered your own question, I cannot think of any feasible method of making it work. It is a pretty interesting field and a lot of it was over my head. I am interested in hearing others opinions.


    • #3

      Around the time that your vehicle was made, I was doing motor vehicle body repair as a sort of hobby after retirement.

      From what you report on the present condition of your vehicle, you haven't a snowflake in hell chance of recovering or slowing down the corrosion.

      There is a Cost Accountant's way of looking at things. You can fill the car with all sorts of proprietory jalop which will cost you the earth both in time and money. At best, you are going to have to go into the outside layer of paint coats, the primers and into the corroded metal itself and shot blast it to remove the pits of rust. The classic question is how does one do all this malarkey in closed boxed sections? The only way is to drill out each weld and remove each unit- and then with a Mig welder stitch through where the welds existed.

      At the end of the day, your vehicle will be still worth the square root of bugger all.

      Getting what little that you can for for your basket case will enable you to buy a newer vehicle which will be probably lighter, stronger, more fuel efficient.

      I have a Merc which is over 8 years old and hasn't a trace of rust anywhere.
      I live in the North of England and close to the North Sea which is every bit as salty as you have and the roads are heavily salted. The salt can still be tasted in high(?) summer.

      Could you be tossing dollar bills down the John?


      • #4
        Originally posted by aviemoron
        Could you be tossing dollar bills down the John?
        Yup, I could. But so far, I have $17 dollars in metal in it, and $300 in the original purchase price. The F350 which donated many parts, paid for itself in scrap metal.

        It is a somewhat nostalgic endeavor. My first truck was a Bronco, and I have always regretted scrapping out my last one. I will not be buying some little econo car. I already have one for my wife. I need a truck to be able to do the work I do, and to play with the toys I play with. I routinely tow a 18' trailer and have outgrown my pickup. I need a family sized vehicle to haul the family and the trailer and the 4x4 buggy on vacations. A new sport utility vehicle is not in the budget right now. Besides, the only style I have ever liked is the bronco, and it is no longer available. This will not cost me a lot of money. I am quite resourceful, and can devote small amounts of cash to it as finances allow.

        If you read the above, you will see than I am cutting out the rust and replacing it. The front fenders, hood, and doors have all been replaced with rust free parts. The rear quarter panel skins will be replaced. I am not looking for any miracles, however, if the ICCP can stop or slow rust on an automobile, I would be willing to try it. If the truck lasts me 5-10 years, I will be very happy.



        • #5
          In order for a impressed current anti corrosion system to work there must be a complete electrical circuit for the current to flow. If the vehicle were under water it would work fine. Since it presumably is not then there is no way to make it work, scam devices not withstanding.

          Galvanizing works by providing a very local galvanic action that favors the electrolysis of the more electronegative material, namely the zinc. I use zinc filled primer spray to prevent rust on chassis areas. It must be renewed every year or two.

          The scam devices such as CounterAct Electronic Rust Protection would have you believe that you can somehow turn your vehicle into a giant capacitor plate with no corresponding complementary capacitor plate and that this impossible feat will help prevent rusting and rust migration. They are careful not to claim that the system is an impressed current system since that is physically impossible. If you examine their testing claims carefully you will find that each testing lab was commissioned to test certain very specific functionalities that have nothing to do with rust prevention.

          Their supposed "Field Testing" consists only of entirely unscientific anecdotal reports by "satisfied" victims, er, customers.
          Free software for calculating bolt circles and similar: Click Here


          • #6
            Impressed current cathodic protection

            Jason, in no way do I wish to deprecate your efforts.

            ( Change of mind)
            Last edited by Norman Atkinson; 12-02-2007, 01:12 PM.


            • #7
              I know nothing about the impressed current, but living in michigan I'm pretty familiar with rust!

              I do a lot of body work because I prefer driving older trucks, they're cheaper and I beat the living crap out of them both work and play, so a new truck is going to be an old truck real soon anyway.

              Only thing I've found that realy works is to use good clean steel when replacing panels, and make sure there is plenty of drainage. I punch holes in my floorboards, and anywhere else that will hold water and dirt.

              My last toy was an 86 bronco2, that I bought used with a bit of rust on it, used mild steel for replacement, and coated everything with phosphoric acid based 'rust conversion' It was the second thing I tried it on, and it seemed to work like a dream, just get rid of the loose scale etc and spray. It does turn black in the presence of rust, but if it's very humid it takes on a milky look. Works great as a primer coat.

              I drove the B2 for nearly 14 years, and used it as a 'family' car when I first got it, as a work truck, and as an offroad beater, finally got rid of it because the electrical system started acting up and I could never track it down.

              The headers on my old bike (1974 honda) are 'painted' with straight rust conversion coat, I tried every paint I could find and it would only last a year average, the most was 2 years, but the coat on these ones is coming up on 5 years old, and still looks 'shiny' and nice. Does get stone chips from rocks etc tossed up by the front tire, but they're easily touched up.
              not a good pic, but you can see the headers here:


              they were actually posted because someone wanted to see what the muffler looked like. Homebuilt from a stainless exhaust tip for a truck, and coupled to an OLD 4 into 1.



              • #8
                Avie, I took no offense, and I do appreciate the advise-- farts and all ... I enjoy working on vehicles though. If I wasn't working on this for myself, I would be working on some off road rig of one sort or another for someone else. My pickup is still worth a little bit of money, and it is paid off. My wife and I just had a little one a year and a half ago, and we have another one on the way. She graduated school, with a teaching degree, and in this area schools are shutting down, there is no work. I am blessed with a full time job at a major chemical plant, but I am afraid I will never own a lotus or maserati. It is not an issue to me though, those things hold appeal to me, but I would much rather have a large family (we are aiming for 5 kids) and a happy wife than any sports car in the world. Anyhow, I need to sell the pickup, and I still need a truck. I am not looking for this thing to be a show stopper, and in all honesty, the exterior rust is not terrible. It is just doing all of this work to replace the rusted floors, I was hoping for a "magic bullet" so to speak, to aid it chances of lasting me several years.

                Here is a picture of my toy. I wouldn't trade it for any sports car in the world! I built it entirely myself, over the space of about a years time.

                Here is a link to the entire build thread on another board if you are interested: clicky

                Do you recall the name of this "rust conversion" product? It appears to me that all of the major brands are very similar products. The "rust bullet" brand I mentioned is phosphoric acid based as well and is also an epoxy encapsulating. I have heard great things about it from non affiliated people, and their web site has a very comprehensive series of pages about the independent testing done, and the results. It comes with a somewhat hefty price tag, but I am told it goes a long ways. One quart sells for approximately $40. I guess, not that terrible compared to automotive paint, but still a lot of money if it turns out to be snake oil.



                • #9
                  You can buy 80% phosphoric acid at a greenhouse supplier for under $20 a quart and dilute it to 40% with water. Use whatever paint that suits you after treatment. Phosphoric acid produces a conversion coating as it converts the red iron oxide to black iron oxide, a stable form that doesn't continue to corrode and actually protects the steel.
                  Free software for calculating bolt circles and similar: Click Here


                  • #10
                    Impressed current cathodic protection

                    The penny will drop for the rest of you.When is not my problem
                    Last edited by Norman Atkinson; 12-02-2007, 01:14 PM.


                    • #11
                      Man, I could have some fun with that toy!

                      Can't remember what the brand name of it is, I just looked for the highest concentration of acid. I've noticed that some of the better known names have lower concentration, I figure I can always thin it if I want/need to

                      I think I'll look into the greenhouse supplier for the stronger mix. I don't do as much body work as I used to, It was at one time a big chunk of my business, but still want things to last.



                      • #12
                        Norm,I realise that some people prefer their cars ready to run,and at the lowest possible cost.But their is a very large portion of people,who thankfully regard modern cars as the dregs of the automotive world.
                        They will slave away in a cold damp garage to restore a relic of times past,whether valuable or not.The cost is in most cases much more than the car(or truck,van,w.h.y.)will ever be worth.
                        I guess it's all part and parcel of the current nostalgia trip running through everything.But the classic vehicle movement has been well established for many years,and supports a large parts industry.And long may it prosper,so we can all go misty-eyed over that 1953 thingummy jobbbob we once owned.


                        • #13

                          Deleted for obvious reasons
                          Last edited by Norman Atkinson; 12-02-2007, 11:49 AM.


                          • #14
                            Matador---------Reminds me of an older friend who, with wife driving, would get out of their old Ford pickup to open the gate to their farm. After pulling through and closing the gate, and before getting back in the passenger side, the friend would pause for several seconds at the rear fender of the truck.

                            One cold night the wife asked what in the world he was doing at the rear of the truck. His answer: Just listening to the trucks' exhaust--nice, steady rhythm, each cylinder firing perfectly, on and on-----

                            Some people just don't get it--------------



                            • #15
                              I don't propose to lecture on saving the planet by getting rid of the gas-guzzler....... I drive a truck, although it gets rather good mileage, almost what the old VW Bug got.

                              But I will say that in general, cathodic protection, electric currents, etc will be ineffective on a vehicle, because corrosion, like politics, is all local without salt water, wet earth, etc to link up all the corrosion sites.

                              What DOES work is galvanized panels, and every manufacturer with any claims to quality does galvanize now. The very name of "galvanizing" indicates an electrical effect, but it is local, within perhaps 1CM of the corrosion site.


                              Keep eye on ball.
                              Hashim Khan