Fuel Tank Cleaning (.pdf)
Your Tractor Parts with ELECTROLYSIS!!!
**NOTE: In order to
save space on this page, the pictures from this
article have removed. They are, however, available
in the .pdf version of this article.**
I have been accused of attempting tractor restoration
on occasion, and because I sometimes run into one
that is not all that, (ahem), pristine, I find that
have need to remove all manner of grease, oil, layers
of paint, and of course rust. After searching the
Internet, I learned of a cleaning method that works
for me and might work for you. That method is called
“Electrolysis”, and I’ll get to
that in a while.
First, some history.
I married a city
girl who after over thirty years of marriage still
can’t understand why I just have to have a
tractor in the garage while her car sits outside.
What can I say? I moved her to Florida from Ohio
so she doesn’t have to scrape windows!
If you have ever
attempted to resurrect an old machine, be it a lawn
mower, tractor, or old car, you know cleanliness
is indeed next to Godliness. I have seen many a
valiant effort to perform a proper rebuild stopped
dead because of a shaving in a bearing, or a speck
of dirt in a newly rebuilt DLTX.
In cleaning parts,
one usually performs the following steps, in some
sort of order: pressure wash chassis, remove part,
soak in suitable solvent, drip dry, apply paint
remover (if needed), use oven cleaner (for heavily
soiled/greasy items), wire brush scrub, wash, dry,
prime, and finally paint. Sometimes, these activities
take place in the residence around the laundry sink
(not recommended), the dishwasher (HIGHLY not recommended),
or the bath tub (now that you’re single, who’s
gonna know?). Now if your part has a fair amount
of rust on it, you should apply something like phosphoric
acid to convert the red rust to black oxide, or
your beautiful paint job may soon have all sorts
of pits and pops before you ever get the first pop
out of the tractor !
On heavily painted
and/or rusted parts, sandblasting had been my cleaning
method of choice, and I still use it. One of the
problems with sandblasting is that you use, well,
SAND!, and it gets into places of which you never
dreamed. Here, again, phosphoric acid as a wash
is helpful, as it will, for the most part, dissolve
the remnants of silica stuck to the metal surface,
and help to dislodge and dissolve any remaining
grains of sand. The downside is that because it
is an acid, it will also erode a small portion of
the part surface, so that you could find yourself
with a shaft journal that is bit smaller than when
a method used by many who restore old tools, hardware,
musical instruments, or anything else that is made
of cast iron, wrought iron, or steel. Electrolysis
to the purist means the splitting of water into
hydrogen and oxygen using electricity, but for our
discussion, we will assume it to mean a solution
that contains water and a suitable electrolyte,
which can be either washing soda (Sodium Carbonate)
or household lye (Sodium Hydroxide), and through
which is run an electrical current. We will be making
an electrolytic bath. In our bath, our part will
have its red rust (Fe2O3) converted to the black
rust (Fe3O4,or black oxide to you tool & die
types). This black oxide is stable in that it doesn’t
want to react with oxygen anymore. Once dry, it
not swell or shrink, so you can safely paint it,
though I like to scrub as much of it off as I can
with some brown Scotch Brite since it removes fairly
easily. This will normally reveal nice shiny iron
metal beneath, among the patches of gray or whitish
material. This coloration is normal.
A word of caution:
While the strength of the chemicals in the bath
is pretty tame, you are still dealing with caustics
that can cause discomfort to skin and eye membranes.
Always use appropriate precautions when mixing,
handling, and disposing of these compounds.
This is Sodium Carbonate. Some folks use baking
soda or trisodium phosphate and report satisfactory
results, but I find that the reaction seems to yield
much better results if I use washing soda. I found
my washing soda in the laundry detergent aisle of
Also known as Sodium Hydroxide, it’s often
found under the Red Devil label. Again, it’s
available at the supermarket or hardware store.
If lye is difficult to find, you can use crystal
Drano (Drano is not my first choice as it has some
magnesium crystals in it that can intermittently
plate onto the iron but it’s not really a
problem). Lye is nasty stuff. Handle it carefully!
If you rub a bit of lye and water solution between
your fingertips, you’ll notice it is very
slick. My old chemistry professor reminded us that
“That’s your top layer of skin cells
sliding around on one another as they come loose”.
USE RUBBER GLOVES AND EYE PROTECTION ! Some folks
say it is getting more difficult to find lye in
their local markets. However, if you keep you eyes
open you will often find it under another product
name in another area of the store. I recently found
this product in the plumbing aisle of Home Depot:
Roebic Crystal Drain Opener. A quick look at the
label shows it is 100% Caustic Soda, which means
it is perfect for our needs.
container(s): Size depends on the parts
you intend to clean. I started with a five-gallon
plastic bucket, then I moved on to one of those
plastic storage containers you find at Wal-Mart,
and now I am building a large tank from a black
plastic, 150 gal stock tank. I ought to be able
to fit most large parts in that. I have also used
the 35 gallon tall plastic cans for long pieces
like hoods. You can use virtually anything, but
stick with plastic.
charger: Now one time someone let the switch
on on my tractor, so now I have a charger. If you’ve
never run a battery down you all might have to go
out and buy one. Big or small, 6 or 12 volt, around
10 amps is fine.
iron, steel, or stainless metal: This will
function as the sacrificial electrode, so don’t
use anything you’ll want to use again because
it will eventually erode into rust (a great time
to put that old cracked “G” cylinder
head to use!). I have used 16 Ga. sheet steel, old
steel fence posts cut and welded together, and old
lawn mower blades. The main thing is you want it
to have an exposed metal surface so that it will
be in contact with the bath. Once the electrode
gets coated in red slimy rust, which will occur
as the part is cleaned (the rust is traded from
the part to the electrode) the reaction will slow
or stop. At this time, you’ll have to stop
and scrub the red rust from the electrode so that
the process can continue. If you use stainless steel,
the cleaning will be greatly reduced or not required
NOTE: A few people
caution about the use of stainless steel for the
sacrificial electrode, because they claim there
is a risk of producing chromium tainted waste products.
However, after much study, several calculations,
and after 30 years of industrial experience with
electrochemical machining of stainless alloys to
the tune of 20,000 pounds per month, I have determined
that I never come close to approaching the technical
and legal quantities of chromium concerns in my
little electrolysis tank. If you would like to read
my reasoning for this position, please continue
to my text on the subject. See
link to F-I-T opinion on using Stainless Steel for
Electrode. Main thing. If you are concerned
in the slightest, stick with common carbon or cast
iron and you will have no question as to the safety
of the process.
I’ll let that up to you.
a part !
Mix your solution
at the rate of one tablespoon of washing soda or
lye to one gallon of water. It’s not critical,
and it will vary from tank to tank, part size to
electrode square area, etc., but add the chemicals
to the water so it doesn’t splash full-strength
on you. Take a stick and stir it a bit.
Place your sacrificial
electrode in the bath, say around the edges of the
container. Place the part in the center so that
it doesn’t touch the electrode. I use old
12-14 Ga. iron wire to connect the part to the battery
clamp above the bath surface. Since we’re
dealing with just a few amps, it doesn’t take
much of a connection. See Figure 1.
Hook up the charger.
NOTE: Two important
dealing with electricity (110 v at the charger)
and water that is in a highly conductive state.
Use an appropriately fused or GFI outlet.
important ! If you hook it up backwards, the part
will erode, and receive the red rust from the electrode.
Hook the BLACK
cable of the charger to the part you want to clean,
hook the RED cable to the electrode that will erode.
Turn on the power and observe bubbles coming up
from the part as well as the electrode. This is
hydrogen and oxygen gas bubbles, and it means current
is flowing just fine. If you have lot of current
flowing, or the meter goes off the scale, you probably
have the part touching the electrode. Shut off the
power, reposition the part, and try it again.
Now that everything
is working properly, go away for a few hours. Time
is your ally. Since this process will only work
on the red rust, you can leave the part in the bath
for weeks, and as long as the electricity flows,
the part will not rust in the solution. If the power
stops, it will begin to rust in seconds.
After it appears
that the part has had all of its rust converted
to black oxide, take it under running water and
scrub it with a wire brush or some Scotch-Brite®
to remove the loose black oxide. Don’t work
too hard. If it still has paint or rust on it, cook
it some more and work on something else. You’ll
note the pits will remain, as there is nothing we
can do to replace the metal that is gone, but now
the part is rust-free. If it needs more time, put
it back into the bath. On a particularly rusty piece,
you will find that if you remove the part and give
it a good scrub, and then put it back in, it will
speed up the process. Now dry it and prime it or
oil it if it needs to remain natural. By the way,
a pressure washer works very well here, too (See
Figures 2 & 3).
is for the most part line of sight, so the placement
of your electrode is important. Feel free to add
as many electrodes as your charger can accommodate.
I even link parts to be cleaned together with wire
until I reach the load of my charger. You can also
pass a rod down into a passage to clean something
out, but you may have to play around with insulating
parts of the electrode so that it doesn’t
short against the part. I have even placed a long
rod from a hydraulic cylinder into a PVC pipe to
soak, and it worked well. Almost any container can
be fabricated. It just has to be able to support
itself, and hold water.
any piece of iron or steel has some rust on its
surface, even under the paint, soaking in an electrolytic
bath can and probably will damage or remove paint.
If you use lye as the electrolyte, this can almost
be guaranteed. For me, that was a real plus to using
this method. The lye electrolyte does the best job
on grease, too. I call it my “Electrical Paint
and Rust Remover”. By the way, I figure if
I run mine 365 days a year, I won’t use over
$60 in power, and that won’t begin to buy
the oven cleaner and chemical paint remover that
I’d need to accomplish the same amount of
I have cleaned
exhaust manifolds, cylinder heads, engine parts,
sheet metal, even bolts with rusted nuts on them,
and have been very pleased with the results. I even
soaked my belt pulley assembly (after removing the
bearing) and it came out very nice. It even cleaned
to flaky rust out of cotter pin eyes and the rust
from the clutch bolt threads.
The solution can
get pretty nasty looking, but it really doesn’t
ever need to be changed, though sometimes you may
want to do so. You can strain it through some panty
hose (but now that you’re single, how you
gonna get those?), or skim off the large pieces
of debris and foam. It’s mildly basic, so
you can pour it out in the yard, and hose things
down well. The grass will like it as it normally
likes to be limed anyway. But please! Check with
local ordinances first!
You can clean
your sacrificial electrode with a wire brush from
time to time, as this helps to maintain peak conductivity.
If I really want to clean the electrode well, I’ll
put it in the bath hooked up as the part, and use
another electrode. That really makes the rust fly
off of the electrode. By morning, it’s ready
to go. Eventually, the electrode can rust no more,
and must be replaced (see Figure 4). Remember, now
is the time to weld together all sorts of bits of
junk. My steel fence post electrode is very rugged
and extremely durable.
If you are going
to prime your part right away, it can be coated
as soon as it is completely dry. If the part is
for an internal engine or gear box use, I oil or
grease it lightly prior to storage, just like you
would if the it was a new part. If it will be a
while before you can get to the priming, I like
to treat the surface with a phosphoric acid product
like Ospho brand, Ph-Ospho-Ric+, or Jasco Prime
and Prep. There are many products out there that
contain sufficient amounts of phosphoric acid, so
read the labels. I have found these three products
at my automotive paint supplier and in the paint
prep aisles of Home Depot/Lowe’s/Ace Hardware.
Here is a typical product label:
After the phosphoric acid has been applied and left
to dry, the part can be stored inside for quite
a while, if not for years. When I am ready to prime
and paint, I scrub the dry surface once again with
a fresh bit of brown Scotch Brite, wipe down with
a tack cloth, and apply my coatings.
very pleased with this process, and I hope you’ll
try using electrolysis on your next project. It’s
simple, cheap, and all you have to do is let the
electricity do the work and sit back and wait for
Opinion on Using Stainless Steel for Electrodes
There are two
types of Chromium compounds that are yielded from
the reduction of stainless alloys in this electrolytic
process: Trivalent Chrome and Hexavalent Chrome,
also known as Cr(III) and Cr(VI). Cr(VI) is toxic,
and as such requires certain handling if it is held
in significant quantity. This is the key. Arsenic
for example is a naturally occurring element, and
it must be controlled if you have a significant
amount of it, but if the quantity or concentration
is small (some is present in most drinking water
in incredibly small amounts), it is of no consequence.
While it is true that the electrochemical reduction
of stainless steel alloys can produce some Cr (VI)
(Hexavalent Chrome), it is important to remember
that not all Cr in the alloy becomes Cr(VI). Most
remains the less toxic Cr(III). Cr(VI) will only
be produced in quantity if you use an extremely
hot reaction (mine stays at ambient plus 10 *F or
less at all times) or in the presence of atmospheric
Oxygen (not present in an aqueous solution). In
an aqueous solution, very little Cr(VI) will be
produced, (I have had the electrolyte from my bath
tested by an environmental laboratory, and the level
of Cr(VI) is virtually undetectable).
The quantity of Cr(VI) is no doubt a concern, but
so is the soluble lead from the paint you are removing
along with the conversion of the Fe2O3 to Fe3O4,
so proper handling of this and other shop waste
is always important. The quantity of Cr(VI) is what
you need to determine, so that you can then adequately
compare this to the CERCLA and RCRA reportable quantities
as published by EPA. As of today, the reportable
quantity of DIRECT release to the environment on
an ANNUAL basis is 1 pound of Cr(VI) per CERCLA,
RCRA, and SARA Title III. This is for non-determined
Chrome compounds. This number can go as high as
1,000 pounds annually with proper analytical documentation.
You can increase this amount even more with increased
handling documentation. For instance, I contain
my electrolyte, and only add to it, so there is
no release. But, if we take this one pound and compute
that the Cr(VI) component of the waste sludge is
5% of an original 18% (a very high percentage of
chrome) of the Chrome by weight present in the original
stainless steel, I would have to digest and then
pour into the ground water, the equivalent of 111.11
pounds of electrodes PER YEAR, and I will not digest
that much stainless steel in my lifetime. This is
why I feel that the continuing statements from some
authors that any and all electrolysis baths that
use stainless steel as sacrificial anodes are creating
hazardous waste that needs to be handled, transported,
and processed and by a hazardous material hauler
Also important to remember is that the carcinogenic
attribute of Cr(VI) is given as inhaled, as other
contact studies have been deemed to be inclusive.
In this electrolysis process it is difficult if
not impossible to inhale the non-boiling electrolyte.
You must not compare the release of Cr(VI) in this
electrolysis process with that that takes place
in the Chrome electroplating process using Chromic
Acid. The amount of fuming and airborne Cr(VI) in
that process is exponentially higher than from this
mild form of electrolysis.
Many folks read or hear from someone that didn't
really know in the first place that Cr(VI) is dangerous,
and began to assume that Cr(III) or Cr(VI) in any
amount is a concern. While it is true that Cr(VI)
is dangerous enough as to dictate proper control
in certain quantities, it is also true of many household
chemicals such as Chlorine Bleach, paint remover,
brake cleaner, MEK, lead paint dust sanded from
old tractors, gasoline, lacquer thinner, Stoddard
Solvent, all old crankcase products, and many, many
Many people are eager to leap to a conclusion that
is not supported by regulations or good science.
It is important to understand that the EPA regards
hazardous as relative to the particular process
you are using, and the specific chemical compounds
released over a given period of time. Again, for
example, Arsenic is a poison, but it also naturally
occurring. If you concentrate it, it can be harmful.
But once you understand the minimum or Rf (Reference
dosage) limits as published by EPA, you should be
able to see that only an amount exceeding that specified
over a given period of time will determine ultimate
toxicity. Reference: 40 CFR, Table 302-4, page 293
and 334 for Chromium Compounds.
I have operated electrolytic processes on and off
for over 30 years. I have served as a line supervisor,
process engineer, materials manager, manager of
technical services, and environmental officer for
a jet engine component manufacturing facility for
26 of those 30 years, so I feel that I have more
than a little experience, but there is always someone
who can teach me more. Any way, we used an electrochemical
machining process on stainless alloys including
Inconel 718 and AMS 5616. I was in charge of disposing
of the filter cake precipitated from the electrolyte,
and I never failed a Cr(VI) filter cake analysis
over all those years, yet we were digesting over
ten tons of stainless steel per month.
I also have a degree and an industrial background
in Chemistry, and it has served me well in understanding
this process as well as the pertinent environmental
regulations. I feel confident that I am observing
care well within prescribed guidelines, and I base
this on regulatory facts and science, and not internet
conjecture, but I invite anyone out there to develop
their own opinion as to how they manage their personal
electrolysis tanks. It is after all, your responsibility.
Some people mentioned their concern about using
Lye, a.k.a. Caustic Soda, chemically named Sodium
Hydroxide because it is, well, caustic. As far as
my choice of using Sodium Hydroxide as an electrolyte,
if used properly, I am confident that there is no
concern. At the rate of one tablespoon per gallon,
it is less than .1 Molar, yet I find that a small
amount will help to emulsify fats, oils, and grease,
and increase the efficiency of the reaction while
held at or slightly above ambient temperature.
So, in conclusion, if you have any reservations
about using stainless steel electrodes in your electrolysis
tank, then don’t. Common steel or cast iron
will work fine, but will require very frequent cleaning
to maintain good current flow. Also, if you have
any concerns about how to handle the electrolyte
(which if filtered from time to time through cheese
cloth to extract the junk and leaves and pieces
of gasket and sheets of peeling paint, can be used
forever) then set it to the side to evaporate and
put the powder residue that is left in a can for
a future hazardous waste clean up day. By the way,
you should also be doing this with all of your household
hazardous waste like car batteries, flashlight batteries,
laptop batteries, spent paint remover, motor oil,
antifreeze, computers, rat baits, old leaded paint
containers, pesticide containers, toilet bowl cleaners,
brake fluids, oil based paint containers, etc. I
bet there is whole lot of decaying Ni-Cad and Alkaline
flashlight batteries rotting in the city dump ready
to contaminate the ground water than there is Cr(VI)
powder swept up from the last time every mechanic
in town cleaned out his electrolysis tank.
If you want to be a good steward to the environment,
you need to be one all the time.
Anyway, enjoy the process and be careful as it involves
electricity and fluid in a highly conductive state.
And if you are the least bit concerned about the
mysteries of Cr(VI), just use some steel fence posts,
but be prepared to clean them at least once a day.
I generally use
a three pronged attack in my war against tank crud,
starting with cheap chemicals and working my way
up in cost and time until the job is done to suit
First you need
to determine if it's just varnish and decomposed
gasoline, and not varnish plus gravel, dirt, bird
feathers, straw, dead mice, nests, red rust, etc,
like one finds in a tank on a tractor that was left
sitting in the fence row with no cap.
To dissolve varnish,
my favorite solvent is Methyl Ethyl Ketone, or MEK.
You can find this in the paint/thinners section
of most Lowe's/Home Depot/Ace Hardware stores. You
may need several quarts depending on the size of
the tank and the amount of varnish in there. Fill
the tank part way, swish it around, and then let
it capped for a while so it can work. Now you swish,
drain, repeat, and maybe use a few nuts or small
bolts in there to cause aggressive agitation, but
steel ones that can be retrieved easily using a
If you have non-petroleum
contaminants in there, hot lye water will really
do the job to emulsify that stuff into a water-soluble
paste that can probably be removed with a good hot
water rinsing. Using a power washer will also help
speed the job. You can also repeat this process
of hot lye rinsing, but be careful that you don't
harm the paint on the outside of the tank if that
matters. If it does not, fill it with a cork in
the bung, and cap it and let it sit overnight. Any
petroleum will turn to a type of primitive soap,
and the dirt will deteriorate into simpler sediment,
both of which can be rinsed out. Again try the nuts
and bolts method during agitation.
The last chemical
I use is Phosphoric Acid. This will convert any
red rust into an inert form of black oxide that
will be harmless if left in the tank. Now, rinse,
slosh, and repeat, until you can no longer see any
rust. You'll want to rinse with plenty of water
to get the foamy, soapy residue of the acid out,
but don't worry about the discoloration left behind.
That is a phosphate coating that will help inhibit
rust in the future.
Now this tank
is pretty much chemically devoid of any vestiges
of flammable hydrocarbons, so now is the best time
to solder any pin holes or place any repair patches
that might be required. I have an assortment of
old solid copper soldering irons that I acquired
years ago, the kind that you heat in a torch or
on a stove and then the bulky copper mass stay warm
for a good long time. Since they use no flame, and
hold they heat really well, they are an ideal choice
for soldering a steel tank. Start by tinning the
area with some good quality soldering paste and
flash a coating of solder about the area. A very
clean, thin, steel patch can now be placed and fully
soldered to cover any large holes. Pin holes can
normally be soldered only with a dollop. Check it
for leaks before moving on.
To finish it,
slosh it with some lacquer thinner and that will
work to drive the water out of any creases or seams.
If you're not going to use the tank right away,
I like to swirl a few ounces of diesel fuel to oil
the inside so no further rusting can take place.
If you want to use it right now, rinse it with a
few ounces of gasoline and let this run out. It
will take any last vestiges of water with it and
you should have a very clean tank. If you want to
paint the outside, you might have to re-arrange
the order of the steps.
Here a couple
of shots of an "H" tank that I used this
process on. I thought it turned out well.