Rust sediment in tank.

Rod R said:

Where minor rust is concerned, I have had really good results with simple vinegar. I'm not a fan of tank liners/sealers in general, but there is a readily available, relatively cheap material called Red Kote that is very easy to use, I've had great results with it.

In the case of rust sediment, I wonder if placing a strong neodymium magnet inside the tank near each fuel tap would work in collecting the sediment over time? You could periodically remove the magnets and inspect them for sediment. If you have never used neodymium magnets, they are powerful to the point of being dangerous.

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Norton tanks normally have baffles that would prevent placing the magnets.

Rod R said:

I wonder if placing a strong neodymium magnet inside the tank near each fuel tap would work in collecting the sediment over time? You could periodically remove the magnets and inspect them for sediment.

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I use them in engine sumps and they work very well, too well if the oil pickup has a ball inside as it does on BSA's, get it too close to the pickup and the the ball does not lift off the seat so the engine wet sumps. Iron Oxide is not as magnetic as iron but with the strength of the neodymium I doubt it matters.

EvapoRust, Metal Rescue are not rust removers or acid etchers, they are rust converters, changing the oxidative state rusted steel back to un-rusted steel. Besure that surface is free of grease/oil/wax etc that may prevent good chemical contact with the product. Best to use a good degreaser in tank like hot water with dish soap followed by thorough washout with brake cleaner or rubbing alcohol etc.
Be sure the products are at the recommended temperature range when using. I just poured in the single 4L jug and tilted the tank around every so often during the several hours treatment to get thorough treatment. Any converted rust appears dark or black following treatment.
I used EvapoRust a few seasons back on both my Norton tanks and have had no issues with rusting since. I do keep tanks near full of petrol when leaving idle for multi week stints and coat insides with motor oil when longer term storage off bike.

What I did on my Commando tank which was badly rusted following storage was as follows:-
- first washed the tank out with hot soapy water and then added a hand full of gravel and shook around for a while. Rinse and repeat, this removes most of the loose rust, bit of a pain getting all the gravel out.
- purchase 500g of powdered citric acid from eBay and mix with approx 8 liters of boiling water, stir until all the citric acid is dissolved, pour mixture into tank, slosh around and leave for a few days. change tank position occasionally to ensure complete coverage.
- after a few days pour out the mixture, its usually green and has rust flakes.
- Rinse out with hot water to remove any remaining rust flakes.
- get a cheap bore scope which attaches to a mobile phone an inspect the tank inside, there should be no rust.
- pour out any excess moisture and then add a strong 80% solution of phosphoric acid. You can buy this on eBay in 250ml bottles, its intended for aquariums. Shosh the phosphoric acid around for a few minutes, the acid should remove any flash rust and add a phosphate layer which protects against future rust.

The tank is now done, make sure to remove any excess phosphoric acid.

If you want you can now coat with POR15 internally, I;ve used it on several tanks and it seems to work well, protecting the tank from rust.

Modern petrol can contain 10% ethanol which attracts water, hence there is more chance of rust in the tank if the bike is used infrequently.

Just wanted to present a 'virtual pint' to gunnag for the excellent tips above.

I followed his advice pretty much to the letter and have to say the tank is like brand new now (on the inside anyway).

It's currently sat on a stool in the garage with the fuel pipe bungs & filler cap removed with a roll of masking tape over the filler and a pc fan drawing in (and expelling) air.



Bloody cheap method too, so thanks to gunnag for taking the time to comment on the post

Evaporust then flushed with diesel. Still have some residual floaters, but just brush off the tap screens and the screen in the banjo and keep going.

Gunnag’s approach seems like a better solution for next time.

For the record: there is a product called ChemPrime which performs rust conversion like Evaporust, but takes the process one step further ..... it leaves a chemically inert film on the surface of the metal to prevent future rust.

After using like Evaporust (rolling the tank to get full coverage) and allowing to set in position for several hours, then drain and allow to air dry. Chemical conversion happens on air dry.

Slick