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my corrosion test for filling with AF or dry blocking

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  • my corrosion test for filling with AF or dry blocking

    The debate always rages about winterizing with a dry block or with a block full of Antifreeze (AF). I decided to do a test for myself last November. I took 2 pieces of mild steel cut from the same bar. I lightly roughed them up with 60 grit sandpaper. My first picture shows the 2 pieces at this point.

    I then filled a container with Supertech RV antifreeze (Wal-Mart brand) and placed piece A in here and sealed it. This is my simulation for a full engine block.

    For piece B, I wetted my hand with tap water and flicked in a very small amount of water into the container. I dipped piece B in undiluted AF and then placed it in the container without wiping it off. This is simulating a block that was filled with AF and then drained. My assumption is that there will always be some water droplets/humidity left over after draining.

    I let these containers sit outside under my covered deck for the past 11 months. On 2 occasions, I flicked in some more tap water in the piece B container (dry block simulation).
    The next picture shows how the two pieces looked today, right out of the containers. As you can see from the after pics, piece A had spots covered in a grayish sludge. The sludge was pretty firm to the touch and it could be mostly removed with hard scrubbing with a paper towel. Once the sludge was removed, you could feel where the steel surface had actually been eaten away by the AF. I measured the worst spot and it had made a hole .006” deep!

    Piece B had a light amount of surface rust showing right out of the container. I was able to scrub some of this off with a paper towel, as can be seen in the after pictures. The rust was purely on the surface. I observed no pitting even under magnification. The rust had built up on the surface only .002” thick.

    The Supertech RV antifreeze that I used does not mention any corrosion inhibitors on the label. The MSDS did show "additives", but no idea if they are for corrosion. If they are, they do not work very well. After doing some research, I found info about how uninhibited ethylene glycol will eventually degrade. This degradation produces acids which will corrode iron, steel, copper, and aluminum. The Supertech MSDS says that it contains both ethylene glycol and propylene glycol.

    Conclusion – I will never leave my engine full of the Supertech AF again. If I am going to use Supertech or any other uninhibited AF, I will use it to flush my system in order to get out any hidden pockets of water. Then I will drain everything out and store it dry. The uninhibited AF should be fine for the ballast system since the only metal there is the bronze pump head.

    I am going to repeat this same test with the Splash brand AF that contains DOW corrosion inhibitors. Peter mentioned this product in another thread. It is available at O’Reillys in my neck of the woods. Using this AF with inhibitors and keeping the block full is most likely the best route to take, if the DOW additives are good. I’ll report back on my testing in a few months.
    Attached Files
    We defy the mafia!

  • #2
    nice write up... very interesting since the regular supertech has ethanol.. which ph is 7.33 less alkaline than the water I ski in. any idea when the sludge began?
    sigpic...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

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    • #3
      I sometimes didn't check on the containers but every other month, so I don't have an exact time. The first time that I saw the sludge was at about the 5-6 month mark.
      We defy the mafia!

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      • #4
        Nice work. Next, just flick some water in with no dip in antifreeze.
        Previous: 1993 Prostar 205

        Red 1998 Ski Nautique, PCM GT40, 310 hp, , Acme 4 blade, Perfect Pass SG/Zbox.

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        • #5
          I'd like to see this test done with cast iron, since that's what engine blocks are made of and mild steel is very different. Cast iron is far more porous.

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          • #6
            Yea, I wanted to use some cast iron, but I couldn't get a hold of any at the time. The cast iron would probably look even worse. I need to go by the junkyard and find a cracked head and cut it up for the next test.
            We defy the mafia!

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            • #7
              Originally posted by blackhawk View Post
              Yea, I wanted to use some cast iron, but I couldn't get a hold of any at the time. The cast iron would probably look even worse. I need to go by the junkyard and find a cracked head and cut it up for the next test.
              My woodworking machines are all in my garage and I found out the hard way that cast iron rusts very easily when I neglected to put paste wax on the top of my jointer before Winter. I had done this to my table saw, band saw, vises and hand planes but the jointer didn't make the list, possibly because I hadn't used it much that year and because I thought it would be OK. I was wrong. I needed it that Spring and when I removed what was covering it, I saw that the whole top had an even coating of rust. I had used a small torpedo heater to warm the garage when I needed to work out there and it's the last time I'll use one of those- it puts out far too much moisture and when warm, wet air meets 20 degree cast iron well,.......

              It wasn't a deep layer of rust, just on the surface.

              You could go to a thrift/antique store and buy a $5 block plane- one of the off-brands would be fine. If you might want to use it, disassemble it, coat the whole base except the sole with grease and do the test. Once the test is over, clean up the sole and it should be good. If you want to sacrifice it for the test, cut it in half with a hack saw and do the test.

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              • #8
                All very interesting. Can't wait to see next years installment. You should give us an update in April or May, as lots of boats are de-winterized then.
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                • #9
                  Originally posted by JimN View Post
                  My woodworking machines are all in my garage and I found out the hard way that cast iron rusts very easily when I neglected to put paste wax on the top of my jointer before Winter. I had done this to my table saw, band saw, vises and hand planes but the jointer didn't make the list, possibly because I hadn't used it much that year and because I thought it would be OK. I was wrong. I needed it that Spring and when I removed what was covering it, I saw that the whole top had an even coating of rust. I had used a small torpedo heater to warm the garage when I needed to work out there and it's the last time I'll use one of those- it puts out far too much moisture and when warm, wet air meets 20 degree cast iron well,.......

                  It wasn't a deep layer of rust, just on the surface.

                  You could go to a thrift/antique store and buy a $5 block plane- one of the off-brands would be fine. If you might want to use it, disassemble it, coat the whole base except the sole with grease and do the test. Once the test is over, clean up the sole and it should be good. If you want to sacrifice it for the test, cut it in half with a hack saw and do the test.
                  I learned the hard way to.. when I was doing woodworking
                  sigpic...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

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                  • #10
                    This makes me feel better about the fact that I dry block during cold snaps. Thanks for the study!
                    I love to travel, but hate to arrive. ~~ A. Einstein
                    ---
                    Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming, Wow! What a Ride! ~~ Hunter S. Thompson
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                    • #11
                      Next try with the old school green antifreeze, from what I understand it is petroleum based. Should be zero oxidation with it.

                      If I know I'm gonna keep a vehicle for a while, I get the pink stuff out asap. Known to cause internal corrosion. But you have to make sure you get it all out, mixing pink and green is the only thing worse than pink alone.

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                      • #12
                        this sums it up.. and a pic of my old risers before and after evaporust.. would need a crap load of evanporust to clear all corrosion.. but a bunch of it before when motor was dry stored..

                        left before - right after - right as a bit less and I was able to rinse out a bunch of flakes...

                        http://www.lytron.com/Tools-and-Tech...ooling-Systems
                        Attached Files
                        sigpic...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

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                        • #13
                          I found the Splash brand on sale today at Hardware Hank for $2.50 gallon

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                          • #14
                            I add anti rust to my RV antifreeze and keep it in the block all winter. No problems. Been doing it for years

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                            • #15
                              Originally posted by uplander View Post
                              I found the Splash brand on sale today at Hardware Hank for $2.50 gallon

                              I found it at true value today for $1.99! Limit 2 per visit though! Anyway looking at label it did say not for use in marine engines. But i think they mean in the cooling systems of closed cooled motors.

                              What's this anti rust stuff people are talking about? Honestly though my motor is filled with lake water 8 months of the year? How is that better than fresh pink antifreeze? I think we are making 2 big a deal about the corrosion protection.

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