Any hints on fixing a petrol tank?

[kerryg]

A good trick for cleaning out your tank, is to put some nuts or chip (stones).
In your tank and shake the bejesahs out of it, but not so hard that you dent the tank.

And count the stones or nuts to make sure you get them all out.
And then flush the tank out well.

Another way is to use a bit of chain. Then you don't have to worry about bits being left in the tank.

I need to clean out a slightly rusty tank (on the inside). It's far from being so bad that it might leak (it's just specks of rust). I don't reckon it needs the full Kreem or POR15 treatment, just needs to have the pre-treatment stage that removes the rust. Anyone tried one of the off-the-shelf rust removers places like Repco sell? Or anyone tried to make up a phosphoric or hydrochloric brew themselves??? Kind of reluctant to part with $70 or $80 if I can avoid it, and I don't want to put a coating on the tank unless it's necessary (which it's not) because of stories you hear about the coating coming off over time

[vifferman]

Another way is to use a bit of chain. Then you don't have to worry about bits being left in the tank.

The problem with that is it wouldn't get into all the little corners. Mind you, neither would gravel (what I used) or nuts.

I need to clean out a slightly rusty tank (on the inside). It's far from being so bad that it might leak (it's just specks of rust). I don't reckon it needs the full Kreem or POR15 treatment, just needs to have the pre-treatment stage that removes the rust. Anyone tried one of the off-the-shelf rust removers places like Repco sell? Or anyone tried to make up a phosphoric or hydrochloric brew themselves???

Just use any 'off-the-shelf' rust remover/neutraliser. While you could use some other acid, it'd only eat the rust, and that's all it would do. The orthophosphoric acid is used, as it turns the ferrous oxide (rust) into a more stable phosphate salt, which doesn't continue to oxidise. Also, orthophosphoric acid isn't as nasty to handle as some other acids, and works well when diluted. Just check the label on the bottle to see what it says before you buy it.

[kerryg]

The problem with that is it wouldn't get into all the little corners. Mind you, neither would gravel (what I used) or nuts.

Just use any 'off-the-shelf' rust remover/neutraliser. While you could use some other acid, it'd only eat the rust, and that's all it would do. The orthophosphoric acid is used, as it turns the ferrous oxide (rust) into a more stable phosphate salt, which doesn't continue to oxidise. Also, orthophosphoric acid isn't as nasty to handle as some other acids, and works well when diluted. Just check the label on the bottle to see what it says before you buy it.

Ta for that. I think I'll try that.

[scumdog]

I have successfully used a 50-50 mix of mollasses and water and left the rusty item in it for a few days and it clears all rust that is not too thick.

You could fill the tank with that mix for a few days, it'll get surface rust pretty quick after you flush out the mollasses mix so you will have to flush it out with a commercial phosphoric acid type rust-kill.

Small holes I have tackeled by drilling the hole to suit a pop-rivet and using a smear of f'glass resin on the rivet before putting it in place, mind you it might not look too flash if there are a dozen or so random holes where you can see them!!

[kerryg]

I have successfully used a 50-50 mix of mollasses and water and left the rusty item in it for a few days and it clears all rust that is not too thick.

You could fill the tank with that mix for a few days, it'll get surface rust pretty quick after you flush out the mollasses mix so you will have to flush it out with a commercial phosphoric acid type rust-kill.

Small holes I have tackeled by drilling the hole to suit a pop-rivet and using a smear of f'glass resin on the rivet before putting it in place, mind you it might not look too flash if there are a dozen or so random holes where you can see them!!

S'pose you could throw in some yeast and then you'd not only get your tank clean but you'd get rum as well.....what's that cocktail???....."a rusty nail" ...OK I'll go away and kill myself now

[scumdog]

S'pose you could throw in some yeast and then you'd not only get your tank clean but you'd get rum as well.....what's that cocktail???....."a rusty nail" ...OK I'll go away and kill myself now

Yeah, know what you mean, sometimes on a hot day my gargre smells like somebody has been on the rum, smell comes from my rust-cleaning brew

'I wouldn't want to join any organisation that would have ME for a member" - also Groucho Marx.

Also: "either this man is dead or my watch has stopped" - said while trying to take a pulse on someone.

[muppitt]

Before welding any gas tank Degas it first. that is to run exhust gas though for tewenty minites .remove the fuel tap for an out let and run a hose from you car tail pipe into the gas tank filler . the carbon dioxide neutralises any petrol fumes .so we wont have to hose you off our roofs

[kerryg]

The problem with that is it wouldn't get into all the little corners. Mind you, neither would gravel (what I used) or nuts.

Just use any 'off-the-shelf' rust remover/neutraliser. While you could use some other acid, it'd only eat the rust, and that's all it would do. The orthophosphoric acid is used, as it turns the ferrous oxide (rust) into a more stable phosphate salt, which doesn't continue to oxidise. Also, orthophosphoric acid isn't as nasty to handle as some other acids, and works well when diluted. Just check the label on the bottle to see what it says before you buy it.

Thought I'd give some feedback on this. I tried the Repco rust remover (can't remember the brand but I think it was made by Newtech...it was one of that stable of body repair products that Repco stocks ) and it wasn't much use. Didn't seem to do anything actually.So I bought the POR 15 equivalent called Metal Ready and it worked a treat. My tank is now good as new or very nearly. Both products phosphoric acid based, so beats me why the difference. So I can recommend Metal Ready for de-rusting the inside of petrol tanks. Best thing is that the instructions for Metal Ready said the product can be re-used repeatedly (just should filter out any debris) so I've recovered and will re-use 800 of the 1000 mils I bought. At $30 odd for a litre it's not cheap which is the one thing against it

[vifferman]

Thought I'd give some feedback on this. I tried the Repco rust remover (can't remember the brand but I think it was made by Newtech...it was one of that stable of body repair products that Repco stocks ) and it wasn't much use. Didn't seem to do anything actually.So I bought the POR 15 equivalent called Metal Ready and it worked a treat.

Fancy that. ONe would expect something sold as a rust neutraliser would actually be strong enough to do a decent job! Otherwise, you may as well use coke....
Were there any indications on the bottles/tins as to the acid strength? I'd imagine the Repco stuff was diluted a tad, to make it more saferer / increase the profit margin.

[kerryg]

Fancy that. ONe would expect something sold as a rust neutraliser would actually be strong enough to do a decent job! Otherwise, you may as well use coke....
Were there any indications on the bottles/tins as to the acid strength? I'd imagine the Repco stuff was diluted a tad, to make it more saferer / increase the profit margin.

I don't understand it either. The conditions were the same pretty much in both cases (similar sort of temperature, same quantity, same method, similar length of time) so I guess it could be down to concentration or perhaps other stuff mixed in with (I'm no chemist as you can tell). There wasn't anything on either package to indicate strength so far as I can remember. But the results were remarkably different. Unless the first application removed some shite and shanky (residual petrol or varnish?) and so the second application was able to work on a better surface or something like that. I dunno.

Phosphoric acid is as cheap as chips of course. Any industrial cleaning chemicals outfit is using it by the tanker load. Hard to figure why a litre of dilute phosphoric should cost $30...

Anyone tried acetic acid (vinegar) for de-rusting? Just a random thought. I know it cleans metal surfaces real well...does it deal to rust? Now vinegar is only, what, $2 0r $3 a litre.....???