Rust removal from inside gas tank

About the electrolylis method, what about a rusty tank that is welded to the frame? Will the current affect/destroy the electrical components; coils ect?

I guess i should clairify a bit. I took a job to inspect, tune up a motoguzzi moped. The tank is welded to the frame and very rusty inside. I'm considering the electrolylis method to remove the rust. The lighting and ign coil is run off of a 6v alternator. My concern is that if I run current through the tank will there be a bleed over effect that will ruin the alternator and ign coil?
 
J ray, you should be ok with the tank welded to the frame. However, if your worried about frying the electrical system, disconect the battery. Thats what is done in autobody shops when they weld in new panels. So they wont create a surge to the computers in the vehicle.
Travis, the battery will help you keep a steady, even flow of amperage to the process. Your needle might not have been jumping around, but a battery ensures a steady current.
 
Dan,

I like this idea no concern about the touching the tank internally by mistake. Did it work on the outside and inside for you?
 
I have an old xs frame that has a lot of surface rust and some big rust on the battery box. would it be suitable to use this method on the whole frame like in a stock tank or would it be best to just have it sand blasted?
 
I would also say blasted since that would remove all the grime and paint and everything making it ready for paint or powder coating.
 
I have used Muriatic Acid (pool acid) with good results. It is some super nasty stuff though so you need lots of caution when working with it. I capped off the petcock holes with aluminum plates I made and thick rubber gaskets to seal well. Put some acid into the tank in a well ventilated area. It will choke you if you get a good wiff. Cap the filler and work the tank in all directions. I find most of the rust to be on the top of the tank that is usually open to air. After a 3 minute shaking I empty the acid and give it another freash shot. The acid works best at the start and seems to weaken after it has done the initial cleaning. Repeat as many times as needed. When happy empty and wash the tank with fresh water and a good soap solution. Dish soap is effective. Wash it 3 or 4 times to be sure. I like to coat the inside with a nice amount os 2 cycle outboard oil to stabilze the metal until it is ready for use. Rinse the oil with gas when ready to use the first time. If there is a good amount of scale rust you can add some chain link to the tank for added abrasion to knock out the rust. The acid can be nuetralized with a baking soda rinse too. It is very strong and dangerous. I have runied clothes working with this and had some skin contact that lets you know it is there. I am not a fan of any seal coating. Most are very temporary fixes and I only see it as an option if the rare tank is not replaceable in any other fashion. With all the XS tanks for sale you should always be able to get one that is usable after a good acid wash without sealing. A slight rust inside will do less damage to the carbs then bad seal jobs or when it decides to start to break down.
 
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After whatevedr method is chosen to clean the rust a rinse with phosphoric acid will create a metal conversion and will resit rust for a long long time. Its used to trat water pipes commercially and it works. It called phosphitizing.
 
I have used Muriatic Acid (pool acid) with good results. It is some super nasty stuff though so you need lots of caution when working with it. I capped off the petcock holes with aluminum plates I made and thick rubber gaskets to seal well. Put some acid into the tank in a well ventilated area. It will choke you if you get a good wiff. Cap the filler and work the tank in all directions. I find most of the rust to be on the top of the tank that is usually open to air. After a 3 minute shaking I empty the acid and give it another freash shot. The acid works best at the start and seems to weaken after it has done the initial cleaning. Repeat as many times as needed. When happy empty and wash the tank with fresh water and a good soap solution. Dish soap is effective. Wash it 3 or 4 times to be sure. I like to coat the inside with a nice amount os 2 cycle outboard oil to stabilze the metal until it is ready for use. Rinse the oil with gas when ready to use the first time. If there is a good amount of scale rust you can add some chain link to the tank for added abrasion to knock out the rust. The acid can be nuetralized with a baking soda rinse too. It is very strong and dangerous. I have runied clothes working with this and had some skin contact that lets you know it is there. I am not a fan of any seal coating. Most are very temporary fixes and I only see it as an option if the rare tank is not replaceable in any other fashion. With all the XS tanks for sale you should always be able to get one that is usable after a good acid wash without sealing. A slight rust inside will do less damage to the carbs then bad seal jobs or when it decides to start to break down.

I am going to reiterate how dangerous muriatic acid is... I was a pool cleaner for 3 years... This stuff will burn you. Will eat through your clothes and gag you if inhaled. So be careful if you use it. Friend of mine dropped a jug once and it splashed right up on him. Luckily it was winter time and it mainly just melted his jacket and some of his hair. He had to jump in the pool in 40degree water...
 
Two separate processes:

Phosphoric acid may be used as a "rust converter", by direct application to rusted iron, steel tools, or surfaces. The phosphoric acid converts reddish-brown iron(III) oxide (rust) to black ferric phosphate, FePO4.

"Rust converter" is sometimes a greenish liquid suitable for dipping (in the same sort of acid bath as is used for pickling metal), but it is more often formulated as a gel, commonly called naval jelly. It is sometimes sold under other names, such as "rust remover" or "rust killer". As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces.

After treatment, the black ferric-phosphate coating can be scrubbed off, leaving a fresh metal surface. Multiple applications of phosphoric acid may be required to remove all rust. The black phosphate coating can also be left in place, where it will provide moderate further corrosion resistance. (Such protection is also provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes.)
 
You are right about the danger involved. I work around the marine industry and it is used regularly to remove marine growth and stains from the bottom of boats. I have had my share of buring sinuses and holes in clothes. It is nasty but is probably the most aggresive when it comes to removing rust. Then again I ride a motorcycle on the streets of South Florida and I consider that a much higher risk taken.

I always wanted to create a device that would allow media blasting inside a tank. A flexible nozzle to get into all locations? Someone told me of a guy who created a tumbling device from an old clothes dryer. He mounted the tank in the drum and filled it with steel shot. After a session of tumbling it came out clean? He was rumored to have tanks sent to him from all over and made a good $ from the service.
 
Two separate processes:

Phosphoric acid may be used as a "rust converter", by direct application to rusted iron, steel tools, or surfaces. The phosphoric acid converts reddish-brown iron(III) oxide (rust) to black ferric phosphate, FePO4.

"Rust converter" is sometimes a greenish liquid suitable for dipping (in the same sort of acid bath as is used for pickling metal), but it is more often formulated as a gel, commonly called naval jelly. It is sometimes sold under other names, such as "rust remover" or "rust killer". As a thick gel, it may be applied to sloping, vertical, or even overhead surfaces.

After treatment, the black ferric-phosphate coating can be scrubbed off, leaving a fresh metal surface. Multiple applications of phosphoric acid may be required to remove all rust. The black phosphate coating can also be left in place, where it will provide moderate further corrosion resistance. (Such protection is also provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes.)



Probably simiar to "Ospho" which I have used before.
 
Someone told me of a guy who created a tumbling device from an old clothes dryer. He mounted the tank in the drum and filled it with steel shot. After a session of tumbling it came out clean?

I think I remember something like that being mentioned on this forum before. Something about putting steel shot in the tank and wrapping it up in a thick blanket or something then throwing it in the dryer on no heat. ... I wasn't sold on that idea.. I'd worry about denting the outside of the tank.

What about a paint shaker? You could modify it to hold a tank and experiment with different media inside.
 
There is a phosphoric acid product called Rust Cure that also has some other additives that are supposed to help prevent rust from reoccurring. I've been using this stuff for years, and I must say it works really well. I usually buy it in a 1qt spray bottle. The Iron phosphate "residue" not only prevents rust from reforming, it is actually suitable as a primer, and can be painted over, so it works well also for things like frames, for example.

I learned the hard way about dislodging rust from a tank using a couple of handfuls of nuts and bolts, and then shaking them around for quite a while. They did a good job, but it took forever to get them all back out of the tank. When I mentioned this to a guy on the Yam650 list, his response was, 'Next time use a length of chain.' Doh! :doh: :laugh:
 
I use POR15 Gas Tank Repair kit. A 3 stage kit , which includes marine clean fluid to flush out fuel residue followed by metal ready (acid) which preps the metal , then the POR15 rust converter/preventative.
Great kit, does a brilliant job, even seals pin-holes!
 
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