Ideas on stripping inside of gas tank?

Slowly going through a KZ550 restoration, and the Gas tank is giving me plenty of problems. Basiccly, the inside is thick with rust (literally looks like it has oozing rust on top of rust. Ive tried the nuts/bolts shaking trick, tried dumping the cleaner from a KREEM kit and letting it sit, and now letting some CLR soak in it. I need to strip the outside of the paint and bondo over the old emblem spots anyway, so I was currious if there is a solution out there that will just eat away everything down to base metal by soaking the entire tanking in say a garbage can or plastic tub.

I have the tank liner all ready to go, but Id rather have it spotless inside before I use it. It's still a solid tank with no holes, and no dents. Id rather try to get it clean as possible then hunting for a replacement. Ill get a picture of the insde probably tomorrow.

You are on the right track the CLR will work given enought time the Kreem acid will eat holes you dont already have I have experienced it it may take a few bottles of clr empty after couple days and reapply.its worth the wait if you dont want to take it to a radiator shop and have it boiled out. aprox 20-40 bucks

as for stripping the paint on the outside just remember old paint is the best primer. with that said I stripped a wheel this week and the Aircraft paint stipper by rustoleum was a disappoinment. I found some at Lowes as poictured below. I learned alot on youtube only let it sit for no more than half hour if that long scrape and reapply. the chemical reaction only lasts for a short time so leaving it over night is no benefit.


9.00 at lowes be sure and use gloves it burns like fire on your skin

if you take the tank to a radiator shop they may strip it while boiling the rust out all at the same time but as far as a do it yourself project do it seperatley

Mcclain wrote: Slowly going through a KZ550 restoration, and the Gas tank is giving me plenty of problems. Basiccly, the inside is thick with rust (literally looks like it has oozing rust on top of rust. Ive tried the nuts/bolts shaking trick, tried dumping the cleaner from a KREEM kit and letting it sit, and now letting some CLR soak in it. I need to strip the outside of the paint and bondo over the old emblem spots anyway, so I was currious if there is a solution out there that will just eat away everything down to base metal by soaking the entire tanking in say a garbage can or plastic tub.

I have the tank liner all ready to go, but Id rather have it spotless inside before I use it. It's still a solid tank with no holes, and no dents. Id rather try to get it clean as possible then hunting for a replacement. Ill get a picture of the insde probably tomorrow.

Hate to say it, but that much rust, it might be too far gone!

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I don't know if this tank is too far gone or not for this, but I have heard many have great results from letting vinegar soak in the tank for a period of time. I guess the time to soak varies on severity of the rust. A week, maybe 2 should do the job if you can wait that long.

Oxalic Acid Rust Removal On Gas Tanks(Found On the internet at www.wgcarbs.com )

Just ordered a few pounds of it this morning, it "should" remove the rust in my Kaw tank and it's great for removing rust on shop tools or whatever too.

I used this stuff while I lived in Florida where the humidity usually averaged 100% and it saved me a lot of labor ... it's Eco friendly too. Our humidity here in Alabama is just about as bad as on the gulf coast ... so even if it won't completely clean the tank rust out ... and I truly believe it will ... I can make good use of it

Don't know why I didn't think about it sooner, mixes with tap water, flushes out easy, it won't harm paint, plastics, aluminum or anything of that nature ... just kills the rust and leaves the metal coated to help prevent future rusting.

The guy's name is Gregg and he has a ebay store but you can buy directly from him, send payment by check or paypal. I talked to him yesterday and told him there would probably be more folks from the forum inquiring about it. He said to have whoever calls or emails to remind him they're from the forum.

It sells for $4 a pound and he can fit 4 pounds into a flat rate priority mail package and ship it for $4.95. So 4 pounds should go along way since it can be used over and over again. $20.95 for 4 pounds shipped isn't bad at all in my opinion. The only way he's making any profit on it is by buying LARGE quantities and selling small.
I'm probably going to set up a large vat to soak tanks and tools in.
This stuff will eventually turn black after heavy use but it still cleans good and washes clean with tap water.
He claims he's had several people use it for cleaning rusty tanks with great results and I know I had good luck with it before too, just never used any on a tank ... but will soon.

Here's his info: Best to try his cell first.

Gregg MacEllven
Sea Shield Marine Products (sales rep)
Mac's Pacs; teak/mahog plugs, flax, oxalic, etc.
macspacs@sbcglobal.net
310-547-2687 (home)
310-547-2606 (fax)
310-721-9667 (cell)

Late yesterday afternoon I mixed up a batch and put it inside my original KZ tank.
The tank had what I would call a medium overall surface rust throughout the inside and a fairly heavy rust build up along the entire bottom surface.

The instructions suggest warm water but I talked with Gregg and he said it wouldn't really matter as long as I wasn't looking for INSTANT results and let it soak so I used unheated water from the hose and about 8 heaping tablespoons of Oxalic acid and let it soak for 24 hours.

I just drained the tank and the water was colored kind of a light brown, I flushed the tank with clean water twice and looked inside as far as I could see with a strong miniature LED flashlight and NO RUST was present ANYWHERE including the bottom surfaces.
The Oxalic acid left behind a off white colored protective coating on the metal surface just like Gregg said it would

Once I got the tank dry I saturated a shop rag with gas and rubbed the white coating with it and the coating stayed put.

But ... I will highly recommend you folks give this stuff a try because it sure takes the work out of removing rust from our gas tanks and it did not faze the paint either where I overfilled it.

This old tank will get repainted and used now that the rust is gone ... but for you folks that have internal surface rust on tanks that still have good paint on them, don't worry ... this is the ticket right here !

I can tell you right now that it works very well, the tanks I cleaned back in November have sat in my shop until I decided to tag & drive my 78 KZ a few days ago.

I looked at all 3 tanks & they still looked rust free inside other than a small haze which may be simply what the metal looks like after sitting so long after being treated. I thru a 1/2 gallon of gas in it, sloshed it around, poured it out, installed the tank with clear gas line & the fuel runs out CLEAN ... no rust deposit showing up in the filter either !

Oxalic acid WORKS better than anything I've ever tried in 30 years of wrenching. Use hot water, mix it up double or triple strength, fill the tank to the rim and let it sit overnight. If you don't get the results you want, do it again, this stuff is cheap and WILL clean the rust out of tanks without harming the paint even.

I kept several gallons of used mix in a large plastic container & constantly throw stuff in it like a set of rusted boat trailer wheels, impact sockets etc. & it cleans them like new, may take a while but it works.


Some tanks may require more acid to do the job but this stuff is cheap & easy to use, won't even burn the grass when poured out.

I did a Honda tank for a buddy that had some ridiculous rust along the inside bottom flat areas & top part of the hump. I tripled the recipe & let it sit a couple of days and it came out CLEAN.

Would rather NOT use a tank liner product that may or may not peel away ... oxolic axid won't hurt the paint either, so that's a huge plus.

gwolever wrote: I don't know if this tank is too far gone or not for this, but I have heard many have great results from letting vinegar soak in the tank for a period of time. I guess the time to soak varies on severity of the rust. A week, maybe 2 should do the job if you can wait that long.

+1 on the vinegar. Its not the best solution. I kinda like MFolks Oxalic solution. At least you won't have to worry about flash rust afterwards and has the same benefit as vinegar. Both are cheap, and environmentally friendly. But I'm just giving my experience with vinegar for what its worth. It is not fast, so it requires that you have time to spare or other tasks to accomplish. I did two tanks over the summer. Each tank had a lot of gunk and rust. I filled them up to the brim so not to have to worry about turning them over. Then stuck them in a storage bin. The first one soaked for 4 weeks, the second 3 weeks. The both turned out equally great. The main thing to consider is temperature. The temp averaged in the 100's during that period. This helped the process speed the process along. I'm sure it would take considerably longer in cooler temperatures. The thing I liked about it was that I didn't have to do anything more than peek once in awhile. Maybe shake the bin a bit every few days.

you could always just reverse electroplate the inside of the tank. Meaning, plate the rust to the anode. This is simple, enviromentally safe, and works great. Just another option for you.

I take all the tanks that come into my dealership straight over to our local radiator shop, they charge me full price, no breaks and its only 80 bucks they strip it, clean it out and seal it. They never fail! 24 - 48 hours and done. I dont know the process they use but they dont damage the paint either.

thanks for all the helpfull info guys! the CLR soaking seems to be doing the trick (although my duct taping sucks so I have to refill it after 12 hours or so). I'll check it tomorrow and see where its at, and towards the end of this process ill toss some wood screws down in there and give her a good shake, then a good pressure wash.

If that fails, i will most likely be ordering that Oxi powder! that stuff sounds like itd be perfect! wish i woulda heard of it before i ordered up the kreem kit :laugh:

Quit wastin you're time!

I've cleaned alot of tanks from many things and almost all the chemical solutions are garbage.

The fast and most effective way at the shop to ensure that 100% of the rust is gone out of the tank is to remove it manually.

Rinse it thoroughly, then fill the tank with water and rubber plug/waterproof tape over the fill hole.
Flip it upside down, and using a rot-zip/plunge cutter - cut the belly out of the tank about an inch in from the perimiter. Its gonna be nice and splashy, but well worth it.
You've now got the tank in 2 with an underside pan, and the top and side edges untouched/damaged.
Simply use whatever means (I like a large wirewheel in a fast drill), to crush out all the rust completely! takes minutes!
Once the inside of the tank is shiney perfect new, take it to a shop and have them weld it back shut - no visible welds anywhere except under the tank, and it only cost about $25.

If you're not going to use it right away, fill it with a 1/2 quart of oil and splash that around real good so it dont rust again.
Remember to rinse it out good with gas before placing into operation.

Peace.

Here is the method Kamasevo refers to


introElectrolytic Rust Removal aka Magic
This is a relatively simple, safe and cheap way to remove light or heavy rust from any ferrous object. I used this process to restore an old wood plane that I bought for $1 (it looked totally un-usable because of the rust). As opposed to grinding, heavy wire brushing and acid bath processes, this method removes none of the original steel and is not noisy or caustic.

How this works:

Several other sites do a better job of explaining the chemistry of this - but basically you set up a conductive solution and insert some sacrificial anodes. You hang your rusted tool in the solution and attach it to the negative end of the power supply. You attach the positive end to the anode and turn on the power. The current travels through the solution and in the process flakes off the rust - the flaking/softening occurs because of the reaction at the surface of the good steel that pushes the rust off.

See this site
for more info on the chemistry of it all.

step 1Gather supplies
You will need:

This project cost me about $40 because I did not have access to a small battery charger. If you have a charger, then most folks with a decent shop full of crap can do it for almost nothing.

- Clean 5 gallon spackle bucket or other plastic container to meet your size needs
- 5 sections of 18” long 1/2” steel rebar ($5 at Home Depot –
buy in longer sections as needed) (DO NOT USE STAINLESS STEEL)
- 5 feet 12 awg (or so) insulated copper wire in two colors
- 5 yellow wire nuts
- several red wire nuts
- 5 feet pliable tire wire (non insulated)
- Box of washing soda NOT baking soda
- Anti-oxidant goo (IE Noalox – This is not necessary
but helps I think.
- Small battery charger or home made power supply ($20-$50 at AutoZone etc) - Its best if the charger
has a 6v option and an internal "trouble" switch that stops charging if something shorts out.
- Variety pack of alligator clips from RadioShack (unless charger comes with decent ones…)
- Outside outlet or extension cord
- GFCI protected outlet (this is a must in my opinion - working around power and water is stupid unless
you have GFCI protection
- 5 gal water
- misc clamps/small boards
- drill with 1/4 bit
- wire cutting and twisting pliars (linemans tools are best
- wire brush (better if on a grinder or dremel tool)
- anti rust spray or light oil
step 2Assemble tank and anodes
NOTE: Do not use stainless steel for the electrodes. As pointed out by a commenter on the intro page (thanks!) "The chrome in the stainless will leach out during the electrolysis and form hexavalent chromium compounds in your electrolyte. These are extremely bad for you." This is true - dont even think about using stainless steel for this project.

Assemble tank and electrodes

1) Space the rebar evenly around the bucket along the sides (running top to bottom). Mark the locations

2) Drill two small holes about 1/2 inch apart 2 down from rim for each rebar

3) Insert a 5" loop of tie wire through the holes around the rebar and out again . Lube the ends of the bar with anti oxidant compound and twist the wire tight and snip off so 1" of the wire is remaining.

4) Once all rebar is in place, make 4 sections of copper wire with the ends skinned off to connect each rebar wire.

5) Wire nut each rebar to the next with a section of cooper wire (connecting the protruding tire wire (I also used Noalox on these connections). Do not connect the first and last rebar (ie: X---X---X---X---X---)

6) Add 5 tablespoons of washing soda to the bucket and fill within 2 of the rim with clean water (adding extra soda will not help&)
step 3Set up hanging clips
Step 2:

1) Find a board (or any non-conductive object) to lay across the top of the bucket.

2) Attach a short lead of copper wire with an alligator clip attached to the water end. (I just stapled the wire to the board)

3) The clip should hang low enough to just enter the water. ( first photo below shows three clips - i was doing three parts at once..)
step 4Attach charger
Don’t mess this step up – the polarity is important:

Make sure battery charger is OFF:

1) attach the positive (red +) end of the battery charger to the rebar wire

2) attach the negative (black -) end of the battery charger to the alligator clip over the water

3) I remember this by saying to myself “the rust flows off the tool towards the positive side”

step 5Attach rusted tool
1) clean a small piece of the tool where you will attach the clip - choose a place where it will also hang securely.

2) Attach alligator clip (which is attached to the negative end of the charger) and and hang the tool completely in the water. Its ok if the clip is in the water – it wont hurt it. Wiggle the clip to make sure you have a good connection.

3) Make sure the tool is attached firmly and is not touching the rebar or any part of the setup that is attached to the positive lead.

4) Areas of the tool that do not have a “line of sight” to the rebar will not be cleaned – if you have a complex part you might need to rotate it or add more rebar electrodes.
step 6Power it up
1) set the battery charger to a low setting (6v – 1.5 amp works great for me)

2) Turn on the charger.

You should see tiny bubbles start to form all over the tool. As the process progresses, the rust will start to flake off and the water will become muddied with rust and goop and foam depending on how fast the bubbles are forming.
step 7Check tool and remove and clean
Depending on the size of the tool, the amount of power used, the amount of rust, and your patience, the process will take from 1 hour to two days. The longer you leave it in the solution, the less work you will have to do to finish the clean up.

The tool will turn black and the rust changes form and flakes off.

If you leave it in long enough, you should be able to wipe the rust off with your finders and find a smooth (but pitted) surface. The nice part about this is that even after only 1/2 hour, the rust is much easier to remove with a wire brush.

NOTE: the tool will not come out of the tank ready to paint. it will still need wire brushing or final polishing with steel wool. the process leaves a gray/black layer of oxidant that you will probably want to remove prior to final rust-proofing or painting.

The photo of the saw below shows three stages: The left side was run for an hour and then brushed. The middle spot was steel brushed for the same amount of time but without the electrolysis (and rust remained) and the right side is the original rust.
step 8Samples
Here are a few samples:

The chisel was very rusted – normal rust removal would have required much original steel grinding to remove the deep pits that a wire brush would not have touched. Check out the stamp that was revealed after cleaning.

The entire project was started because I bought this sweet plane that was totally rusted. I only paid a few bucks, but knew that a used non-rusted one was worth quite a chunk of change. After the tank proces it took about an hour of going over it with the light wire brush wheel on the dremel to shine it up – but it would have been impossible without the electrolysis first.
step 9Final Rust proofing
If you are not going to paint the tool then it will require immediate rust proofing.

I use this spray T-9 stuff that Highland Hardware sells

– but I think there are some less noxious easier to clean up products out there like Camellia oil
step 10FAQ

How big/small of an object can I do?

- My browsing around on the web found people doing anything from small parts in a 1/2 gallon tub to a trailer body in a swimming pool using a large welder for the power.

Does the solution "wear out"?

- No - it just gets nasty

How much power should I use?

- As little as possible to still get the job done. I think you will get better results with low power and two days of processing than high power and getting it done in an hour. The larger the object (surface area) the more power required to do it in a given amount of time. My charger is 1.5 amp 6 volt and works great for hand tools. the small stuff takes a few hours. The larger complex plane took a day and a half before i was happy with the amount of removal.

Is this dangerous?

- Only if you don’t have any common sense and don’t use a GFCI protected power source.

- Yes if you do it inside - the bubbles forming are evidently hydrogen which is flammable. Outside it does not cause any problems.

- The low voltage is pretty safe - especially if your charger has an automatic cut off "trouble" switch.

Are there any drawbacks to this system?

- Some people say that depending on the power and time involved, the steel can become brittle due to a temporary change in structure. This is cured by "baking" the tool for a few hours at 350 in the oven or letting it sit around for a few months before any hard use. see the links below for more info. I have not found this to be a problem.

These guys deserve the credit for teaching me how to do this and provide way more info on this system:

www3.telus.net/public/aschoepp/electrolyticrust.html

myweb.tiscali.co.uk/andyspatch/rust.htm#top

antique-engines.com/electrol.asp