Continuing the theme of winter repairs and the fight against corrosion, I would like to recall the rust in the gas tank. This problem appears to owners of older motorcycles. Few are immune to corrosion. She always crawls out in unexpected places and at the wrong time. Rust forms after damage to the anti-corrosion coating or after constant driving with gasoline on the bottom.
So what to do if you find rust in your tank?
The easiest way
The easiest way is to entrust the matter to professionals. Yes, it will cost money. It may happen that not every workshop will offer such a service. But it is not for you to teach a young chemist or physics lesson. The matter will pass without burns and unnecessary adventures.
Prepare the tank and work area
Since gasoline is not the most useful liquid for a person and its vapor is also not a fresh southern wind, be sure to prepare the place of work. You need very good ventilation or even open air. Vapors of acids, which are to be handled further, are similarly harmful to humans. I also advise you to think about a respirator.
Gasoline is drained from the tank, its residues are allowed to drain. The tank is removed. Inspect it from the inside with a thin flashlight to understand the magnitude of the disaster. It is important to know where the liquids should be in contact with the rust for longer. You may need to turn the tank at a certain angle and leave it there for a while. Remember where the corrosion is most, these are the places you need to work with.
You will need heavy rubber gloves to protect your hands. Acids should not get on the skin and even more so in the eyes. Be careful.
Mechanical method for advanced cases
This method is called “old-fashioned” because it is as old as our dreams. If corrosion has gripped your gas tank tightly, then before you fill it with chemicals, you need to break the thick layer of rust. For this, sand is poured into the tank. I do not presume to advise to insert bolts or nuts there, simply because we do not need damage to the “healthy” walls and scratches on them. The sand will make the work softer. There is not enough pressure for the sandblasting effect, but instead you have to work with your hands – shake the tank well.
There is a recommendation to beat off rust with water pressure from a Karcher, but I will not recommend such an extravagant method. I do not really believe that everything can be clearly cleaned from the Karcher, except that large pieces can be chopped off, and even then not everywhere. The problem with cleaning the gas tank is that it is an enclosed space with a narrow opening, which means that not all cavities can be cleaned out with the same success.
The modern market offers many options for rust converters. It is enough to take a special solution and just follow the instructions. But if this is not for you, then you can turn to pure acids. Phosphoric acid is often used in rust converters. The very acid behind which there are so many stories of soda washing off fine rust. Therefore, users buy it in its pure form, dilute it with water and wash out the corrosion.
In addition to orthophosphoric acid, acetone, citric acid, phosphoric, formic and vinegar are used. The second most common after phosphoric acid is acetone.
Acids must be prepared before being poured into the tank – diluted with water in accordance with technical specifications. The higher the concentration of acid, the greater the risk of damaging the “healthy” walls or that the acid will “eat up” excess in place of rust.
If we talk about vinegar, then it is left in the tank for a long period of time, for 10-12 hours. The tank is inverted and shaken periodically.
Other aggressive substances such as acetone or phosphoric acid are poured out after prolonged shaking and a downtime of a couple of hours. A corrosion inhibitor called “Catapin” can be added to orthophosphoric acid. It is a technical mixture of alkylbenzylpyridinium chlorides or polybenzylpyridinium chlorides. There are other inhibitors, the question of the ability to buy all the components and mix them correctly to the volume of the tank.
After the acids have been drained, their residues must be neutralized, since the action of the substances is still continuing. Most often, it is enough to dilute the soda with water and rinse the tank with this solution. Then they rinse again with running water so that there is certainly nothing left. Next, the tank is left to dry. It is allowed to flush with an additional couple of liters of gasoline.
There are other sophisticated methods for cleaning rust from a motorcycle tank, which we all inherited from past generations, but they are expensive in terms of time and nerves. Now, with the demand for technical fluids, finding the right acid or rust converter is not so difficult.