Removing rust from a fuel tank How to.

[Pasc]

I thought some of you good men might find this interesting / helpful if you are about to start restoring that rusty old tank.
I lifted it form another site I'm a member of (750turbo.com).

Electrolysis isn't a rust conversion, rather a rust removal. You hook up a DC power source (like a 12V car battery charger) to the part you want cleaned (negative terminal, or cathode) and to a throwaway piece of metal (positive side, or anode), which is separated by a medium which conducts electricity, a watery solution in this case.
It's the best way of doing it, as it's the only way that you don't lose any base metal (acids and such remove some good stuff too).

1) Remove all accessories from the gas tank except the cap (everything in the bottom) and plug off the holes with blockoff plates. You don't want aluminum involved, so don't use that for any blockoffs.

2) Make an anode (positive charge side) from a piece of metal that will fit into the tank without touching the tank. Larger is better. Suspend it from the filler hole using an insulator so it doesn't conduct electricity, leaving a bit of it sticking up out of the tank.

3) Fill the tank with a mixture of 1 tsp. washing soda (can be found in some stores, or online at soapsgonebuy.com which is where I got it) for every 1 gallon of water.

4) Connect a 12V car battery charger. Negative lead to a clean metal part of the tank, positive to the suspended anode (polarity is important!) making sure they don't touch each other.

5) Plug in the charger set to 2 or 6 or 8 amps, or thereabouts. See the bubbles. Yay.

6) Wait some number of hours depending on current setting, anode size, and tank size. The anode will probably need cleaned sometime during, as it rapidly corrodes and collects the loosened rust. After several hours or more, shake the tank vigorously then dump the nasty water (it's safe, just soapy and rusty). Immediately put some gasoline in there along with nuts and bolts or marbles or something removable like that, shake the heck out of it, then dispose of nasty gasoline properly. Remove all marbles or whatever, put more gas in, shake more, empty properly again. Congrats. You now have an internally rust free gas tank.

In short, the process separates the H2 from the O in H20 (that's water, genius ). You "create" 2 parts hydrogen and one part oxygen. Doing this loosens the rust from the metal you're trying to clean (in this case, that rusty Turbo gas tank). Those hydrogen bubbles are forming on the base metal, under the rust. Once it's free, it migrates over to the anode, which is creating oxygen bubbles and rapidly corroding as well. Once it's done, there will be no more rust, just a pitted bare metal surface (depending on how rusty it was, hopefully not bad enough to create holes or very brittle metal), and your anode will look like this:



Please excuse the sucky pic, the good camera needs a new battery. That's my anode, a bit of generic automotive exhaust hanger from a roll. Notice the tip, where it still looks new. This is how the rest of it looked 24 hours before. Crazy!
Sorry I don't have any pics of the insides of the tank, the aforementioned camera problem prevents it. It did look pretty nasty and was flaking, though there aren't any holes or brittle spots. Now it looks clean, but a bit pitted. The best part is that it works!

Let me start by saying that I'd like to have pics of this stuff, but I don't yet.
I'm an Electronics Technician, so I just had to do it this way, even aside from all the actual benefits.

I started by rinsing the loose flaky stuff out with water very well (I had already drained the rusty gas, removed the tank, and let it dry). Once I got most everything out, I removed everything from the tank except the fuel cap. The top display, fuel float/sending unit, return check valve (which is aluminum), and fuel tap all went.

I then made a block off plate for the fuel tap hole out of a strip of steel I had by drilling two properly located holes for the mounting screws. The strip is about 5" long because I didn't feel like cutting it shorter when I didn't need to, but it doesn't have to be that long of course. I applied plenty of RTV to the surface, covering all of the exposed metal (just in case, and doesn't hurt). While RTV can't stand up to fuel, it does just fine with voltage-laden soapy water. Then I tightened the screws onto it, mildly snug.

For the fuel float/sending unit I did pretty much the same, except I found a thin brass plate of about the right size. To cut out the right shape and hole pattern, I used the original gasket as a template, which was rough at best. I cut the shape with my dremel, and drilled the holes. After massaging a few of the holes with a file, it fit. I did the same with the RTV, covering the whole side of the plate just in case (I actually experimented with a scrap piece, and electrolysis doesn't hurt it, just cleans it as long as it's the cathode). The mounting screws were a little tricky because they have larger diameter non-threaded shafts halfway, until they become smaller in diameter and threaded toward the end. I made sure I drilled holes just big enough for the threads to go through and just small enough that the larger diameter part of the shafts rested on the plate, holding it on. You could do it other ways (thicker plate, shorter full threaded screws, etc), that was just easiest for me with what I had. Snugging them up mildly with the RTV applied created for a leak-free seal.

As for the return check valve, I went to the parts store and bought an oil drain plug of the right size (Sorry, I already forget what size it is), which had it's own gasket. Screwed it in, easy as pie.

My bike is a California model, so it has two more nipples for the emissions junk, I plugged those with vacuum caps (and they remain that way). I'm not sure if the rest of the world's Turbo's have these or not.

The crummy pic on the last page shows my anode, which looked perfect at first (it actually looks worse now than the pic lets on to, it's about to fall apart). As you can see, it's an upside-down V with enough at the top to stick out of the tank about an inch or two. One side of the V went on one side of the hump in the tank, and the other on the other, simple enough. I bent it so that it made it all the way in without touching anything. You want to get both sides, as the electrolysis works better the closer the anode is to the cathode. It ended up working on my whole tank this way.
The top portion sticking out has a hole (the second to top) strategically placed to put a dowel pin through it, which rests on the edges of the tank's filler hole. It probably would have been easy to go across the street to Home Depot Racing and buy the right size wooden (non-conductive) dowel (as a pencil or pen is too big), but I opted to use a metal dowel of the right size that I already had (for the installation of my 1100's spin-on oil filter conversion kit), and I used two short pieces of shrink tubing to isolate it from the tank. Looking back, a wooden dowel would have been easier, heh.

Once all that was done, I removed the anode and filled the tank with warm water and added 5 teaspoons (close enough) of washing soda. *Note: you need washing soda, not baking soda. I'm not sure why on this, but I know the washing soda works well at least.* I then closed the filler cap and shook vigorously to mix it up (it took a couple minutes to dissolve). I next flipped the tank over, removed the fuel return plug, filled up the rest of the tank, reinstalled the plug, and flipped it back over. I wanted water to reach the top since it was rusty too.

I clamped the negative side of the (unplugged) battery charger onto the fuel return plug since it was cleanly threaded into the tank, and measured the resistance with various points on the tank to make sure it had good continuity.

Once upright and open again, I re-inserted the anode, bending it to the right shape again then clamping the positive terminal of the (unplugged) battery charger onto it, on the top section above the dowel. This was the most annoying part of the whole thing, getting it to sit in there while under water through the tiny hole with a dowel in the way without touching anything with the charger clamp pulling on it. I tried to measure the resistance to make sure it wasn't shorted to the tank since I couldn't see inside, but it measured <1ohm no matter what, I guess that washing soda solution makes for a very good conductor. In the end I just felt and listened while moving it around until I was pretty sure it wasn't touching, heh.

Once it was all set, all that was left to do to begin was to plug in the charger, set at the lowest setting to test (2 amps on mine). The bubbles started coming and nothing blew up , so I bumped it up to 10 amps. The bubbles got stronger, and I went to eat dinner, checked on it, then went to bed.
The next morning I had to work, but didn't want to leave it as it was for fear that collected rust might short out the circuit and turning it off might rust again, so I unplugged, removed the anode (now nasty) and cleaned it off, reinstalled with as much frustration as before, then restarted it and left it on 2 amps since I was going to be away.

After work, about 22 hours had passed total, so I unplugged the charger for a final time and removed the nasty anode, rinsed it off (it then looked as it is in the pic on the previous page), and dumped the disgusting water, shaking as I went. Here's where I should have used gasoline to rinse it as I stated above, but I used water because it was easier and cleaner. I figured it wasn't enough time to hurt it, but it turns out that this newly exposed perfectly bare metal starts corroding rapidly until something is there to stop it (fresh gasoline) I rinsed it several times until the water came out clean, then looked inside and saw a wonderful lack of orange-brown. Sweet! I did find a few bits of rust still attached (or so it looked like), but it came off with the touch of a screwdriver. So then I borrowed Christine's glass-rock marble things (she actually let me!) and dumped 'em in, shook with more water, and more nasties came out. Once all the marble things were out, I dried the tank by pointing our de-humidifier's airflow at it. The next morning is when I noticed a small, fresh layer of slight surface rust. :/ It's not enough to hurt anything, so I don't care too much. I rinsed with gasoline, came out clean, so then I pulled all the plugs, reinstalled everything including the tank onto the bike, and filled-er up! Ta-da!

*Notes/Disclaimers*
-There is a -very small- hazard of explosions, possible spark and hydrogen with oxygen being there and all. I wasn't worried. No suing or blaming me if you blow yourself up.
-Use a well ventilated area, the gases may be harmful
-I heard you shouldn't use a stainless steel anode, it'll release poisonous gasses.
-Don't put the battery charger clamp into the solution, it'll get eaten too!
-Make sure the negative lead is on the gas tank, as rust will accelerate rapidly if you flip the polarity!
-Clean the anode during the process some, you want it to be conductive and clear of debris (rust).
-You can use other battery chargers, in theory the higher the voltage the faster it'll be done, but 12 volts with 10/2 amps seems to work well enough.
-No matter how hard you try not to, you'll make a mess. Keep this in consideration.
-Use gasoline to rinse it as I outlined in step #6 above, not water (heh).
-You shouldn't need to coat the tank if you keep it filled with gasoline or in use, but if you want to anyway I've heard that POR 15 is the best. I have no personal experience with coatings, though.

*Credit for the idea goes to researching on the internet and various other internet write-ups.

[wilsonsjw11]

PASC
EXCELLENT AND INFORMATIVE THREAD

[bedlow1]

Very Good
why dont you send this info for inclusion in the club magazine? they get desparate for articles to include

[Pasc]

Bedlow, It's not my work. I found it on 750turbo.com and thought it was worth showing you guys here. I'll try and find the original post again and put up the link as there were a couple of pics that did'nt come over when I copied it here. I can't see any reason why it can't go in the mag though if Chris feels it's ok.

[Pasc]

Here's the original post. Some interesting discussion since I last viewed it.
http://www.750turbo.com/forum/viewtopic.php?t=6892