Rusty tank

[PaulP]

Hi

i have done loads of work to get my gsx1100esd back on the road, I think everything is looking good, I went to empty the tank and refill with new fuel only to find it’s gone rusty in the last few years, no idea why as it’s been ok with very little use for the previous 20 years, so I have looked on YouTube and see acids and electrolysis being used but would prefer to hear from someone who has actually done it and the pros and cons, I am in the uk so if anyone can recomend products available here that would be great

 

[Joseph]

I guess you want to keep the current paint ?

I always do mine with white vinegar. It's the cheapest acid you can buy, it's not toxic and you can get it on you without ending up looking like a bollywood reject

Make a steel blanking plate and seal the fuel tap hole with a couple of bits of old inner tube (don't leave the alloy one one, the vinegar will eat through it.

Fill the tank up and leave for a week or so depending on the condition. It's a light acid so it takes time, on the other hand it won't eat into the steel.

Rinse out with a hose pipe, and use a good amount of sodium bicarbonate in a couple of liters of water to swirl around after a very thourough rinsing. 

That will neutralise the acidity.

 

But I'm talking tanks that get painted afterwards

 

I have seen several tank sealer kits, and the instructions state at the rust destruction phase, to protect the shit out of the paint finish because the acidity can get to it if not properly protected.

A greasy stick thick armored sticky tape should isolate it, you need to lay it down nicely around the filler neck ( part of which is bare steel so leave that in the open, don't let the tape overlap the bare steel/painted steel because you could get seepage into the paint.

Edited October 18, 2021 by Joseph

[yantosh]

i use molasses and water mix, leave it a couple of days , rinse it out and line tank with some kind of duck oil type stuff 

[PaulP]

Thanks Joseph, white vinegar sounds safe enough, yes I have good paintwork that I need to keep, any idea if you can buy the vinegar in bulk rather than a trolley full of 1ltr bottles ?

[Joseph]

Yeah i get it in 5L tubs at big supermarkets, and actually even my big/pro hardware store sells in in 10L

[Dezza]

Citric acid is available in powder form as a food additive. It is a very effective rust remover as is oxalic acid, which is also available cheap in powder form. You can then make up your own solution. I fill first a rusty tank with the solution, leave for a few hours then drain. Then fill 1/3rd and add a load of (non-stainless) fasteners, seal the tank and shake the contents around every now and again for another few hours. Then drain. You will be able to remove the difficult fasteners with an extendable magnet. Then flush with water and dry as quickly as possible.

I have heard the molasses method is extremely effective as Yantosh says and will be trying that next if I have to de-rust a fuel tank to compare the ease/effectiveness of the two methods.

[Swiss Toni]

Black treacle (Molasses). Mix 1 tin with 1 gallon of boiling water. Takes a while, but won’t damage paint. How about Electrolysis? Washing soda, battery charger, bit of sacrificial steel and away you go!

Robert’s your Mothers Brother!

[Joseph]

Same acid content in molasses as in white vinegar FYI  so the same potential attack eitherway on a same level of dilution

[PaulP]

Hi

i think I will try the citric acid in powder form, any ideas on strength , I only see it normally stated as a flavouring or for bath bombs, but my tank is a fair size 

[TonyGee]

i did one of my tanks with white vinegar and it did a good job, but within an hour or so i could see surface rust appearing. 

[Swiss Toni]

Phosphoric Acid is a good rust remover. I've used it a few times in the past. Dilute 1 part acid to 4 parts water. Brim the tank, and let it sit. When you're happy, rinse out with water and baking soda to neutralise the acid. Dry asap. It leaves a coating that won't rust.

[Joseph]

2 hours ago, TonyGee said:

i did one of my tanks with white vinegar and it did a good job, but within an hour or so i could see surface rust appearing. 

Did you passivate the acid action with a dollop of sodium bicarbonate in the last rinse ? 

[TonyGee]

1 hour ago, Joseph said:

Did you passivate the acid action with a dollop of sodium bicarbonate in the last rinse ? 

nope 

[rodneya]

I use electrolysis on my Katana tank. The last few rounds I used TSP solution. It leaves a phosphate coating that prevents flash rusting after rinsing out the tank. Its pretty slow, but it worked perfectly. I will not damage paint either.

[Zenerdiode]

What’s TSP solution, please?

[PanzerWomble]

28 minutes ago, Zenerdiode said:

What’s TSP solution, please?

A quick google will give you the answer, and also where you can buy it .

[cnap504]

TriSodiumPhosphate, aka tsp