Rust in Tank

[boilermaker1]

Hi all
I have some very mild patches of rust on the inside of  my petrol tank.
What is the best cure for this ?
Thanks in advance

[sgd37]

I treated my badly rusted tank with phosphoric acid. About 45% concentration swish around until there is no more rust (about 5-10 min), empty, wash out remaining acid with coca cola (yes I'm serious, it's the only way I found to stop it from flash rusting), then put in methelated  spirits (300ml) to absorb all moisture, finally wash out with petrol. It should leave a rust resistant iron phosphate layer. Mine has had this treatment and has remained rust free since. Also be careful that the acid will attack the petcock so don't leave it in too long or take it off completely.

If you can reach the rust then coke and rub with tin foil works well due to the phosphoric acid in the coke.

[Clunker]

That sounds like good advice sgd37 but I'm wondering does the acid damage paint?

[sgd37]

I had a few spillages while doing mine and the paint didn't look affected at all. Obviously I didn't leave it on there but washed it off with water with some bicarbonate soda mixed in. Phosphoric acid is pretty safe as long as you take sensible precautions. It is only stuff with magnesium in it that is at risk.

[philgresty]

Fill it full of vinegar and leave for atleast a few days

[Colonial-Clive (yindi)]

I used brick/patio cleaner (hydrochloric acid) 1gallon for about £10 from your local builders merchant. Pour in leave for 15 mins empty back into container repeat if needed. Then rinse with water and then with petrol. Worked a treat on mine.

[gtmdriver]

Use Deox-C from Bilt Hamber.

Does not affect paint or any other material. Dissolves rust but leaves good steel unaffected. Non-toxic and biodegradable.

It will clean the interior of the tank down to clean steel.

http://www.bilthamber.com/deox-c

[Clunker]

Use Deox-C from Bilt Hamber.

Does not affect paint or any other material. Dissolves rust but leaves good steel unaffected. Non-toxic and biodegradable.

It will clean the interior of the tank down to clean steel.

http://www.bilthamber.com/deox-c

I followed the link and this does sound like a good product according to the reviews but I was wondering if you have to treat the inside of the tank afterwards to stop flash rusting?

[AshimotoK0]

We have a heated tank of  it at work .. it's good but you may be better with phosphoric acid that leaves an anti rust phosphate coating on the metal. DeoxC is a chelating agent much like oxalic acid but non toxic. I think most tank sealing kits use phosphoric acid treatment prior to application of the coating. 

[gtmdriver]

Deox-C is far more efficient than phosphoric acid at actually removing rust but if you want a protective coating on the inner surface you could always give it a swill round with a phosphating agent after removing all the rust with Deox.

POR15 Metal Prep works well.

[AshimotoK0]

I reckon the best method of rust removal is mechanical. Small sharp metal things shaken around using cement mixer or  big tumble  drier etc with tank suitably protected of course. Watch Deox C with chrome .. if you leave a long time, the Chrome starts  to blister and strip....    DAMHIKT ! Also seem to remember it blackens the likes of some gear components etc.