Mike C Posted January 7, 2019 Report Share Posted January 7, 2019 (edited) I've had problems in the past with pits in the bottom of steel tanks because any free water in the fuel tends to collect in the pits when the car's standing- worsening the pit corrosion. I try to avoid ethanol fuels but I suspect my current aluminium tank would be suitable for low ethanol levels. The US boating manufacturer's association NMMA had a position paper on tank materials and ethanol I've attached There's a lot of cars running with aluminium tanks and I've not heard of any ethanol corrosion problem. Ethanol Fuel's & Tank Materials.doc Edited January 7, 2019 by Mike C Attached document Quote Link to post Share on other sites
71 V12 Posted January 7, 2019 Report Share Posted January 7, 2019 22 hours ago, Keith66 said: Hi All Thought I'd give a bit of an update on the very rusty inside of my fuel tank (see original pics) After a lot of faffing about I’ve made some substantial progres, although not without issues. So first I used cellulose spraying thinner to get rid of any old fuel residue, then agitated with a couple of kg’s of nuts and bolts to try to remove any loose stuff, but I couldn’t use ED’s automated cement mixer method as errr sadly I don’t have one round the back of the garage and by hand that was flippin hard work, well for at least 10 mins anyway. But I did follow his recommendation of using phosphoric acid solution in the tank to remove the rust. I used 45% solution and as you can see from the pics it works pretty well (well miraculously really). However one issue is that a 5L does not cover the fuel return pipe that goes into the swirl pot so as you can see from pic 2 its not clean. So I get to do it all again with a bit more solution, Yeah!! What fun. Cheers Keith Hi Keith, Very impressive result. I need to clean my tank also, where do you get phosphoric acid from and how is it mixed? Regards, Kevin Quote Link to post Share on other sites
Keith66 Posted January 17, 2019 Author Report Share Posted January 17, 2019 (edited) On 1/7/2019 at 10:36 PM, 71 V12 said: Hi Keith, Very impressive result. I need to clean my tank also, where do you get phosphoric acid from and how is it mixed? Regards, Kevin Kevin Sorry missed this one. Got some 45% Phosphoric Acid from a company called Azure Liquid Solutions in Haydock. They have an e-bay shop which is the easiest way to get this kind of stuff and for around £18 for 5l delivered, thought it was pretty good. The effectiveness of the rust removal / conversion is spectacular but some prep is needed, see my return pipe problem. As is aftercare. So the above pics are after the Acid has been removed and when it was more or less dry. Now recommendations are to rinse with water to get rid of any acid residue. Which seems and sounds 100% sensible, so that’s what i did. But that has left me with very slight and fine flash over rust., see pic. So 2 options at this point 1. Do it again to get rid of the flash rust and don’t swill it just let just dry? After all I’ve read Phosphoric is too weak to damage the steel directly in any meaningful way and surely won’t damage the petrol (explosions?) but hey I’m no chemical engineer so what do I know, just do a bit of hoping. 2. Ignore the flash, its very slight anyway and the tank is hugely better than it was and any condensation in the tank with cause some rust at some stage and what are filters for? Actually that was the reason I asked if the original tanks had any kind of surface treatment like tinning as mine seems to rust very quickly now after all its harsh treatment over the years. Cheers Keith Edited January 17, 2019 by Keith66 add pic Quote Link to post Share on other sites
ed_h Posted January 18, 2019 Report Share Posted January 18, 2019 Kieth-- What you are seeing there may actually be iron phpsphate: https://en.m.wikipedia.org/wiki/Iron(III)_phosphate Ed Quote Link to post Share on other sites
Keith66 Posted January 19, 2019 Author Report Share Posted January 19, 2019 Hi Ed Not really sure what it is. I'd just kind of assumed water + bare steel = flash rust no matter how quick the dry process. I was using Bullfire as inspiration, except the mixer, lol, and got pretty much the same results from the Phosphoric acid stage. But not sure if you rinsed with water after that or not as it doesn't seem to be mentioned. Thansk Keith Quote Link to post Share on other sites
RogerH Posted January 19, 2019 Report Share Posted January 19, 2019 Hi Keith, not sure if this is the right thing to do but why not use petrol to flush out the Phosy. Roger Quote Link to post Share on other sites
ed_h Posted January 19, 2019 Report Share Posted January 19, 2019 Keith-- I did rinse with water after the Phosphoric, mainly to get rid of any left over acid which might dry to a whitish film. As mentioned in the wikipedia article, phosphoric acid leaves a coating of iron phosphate on the steel, which inhibits corrosion. Normally, well-bonded iron phosphate is kind of a grey color that looks like bare metal, but if there is some excess phosphate on the surface, it can have that rust color as shown in the wikipedia image. Ed Quote Link to post Share on other sites
Andrew Smith Posted January 19, 2019 Report Share Posted January 19, 2019 Anyone tried this stuff (Scale-X) - https://www.tmchemicals.co.uk/scale-x-phosphoric-acid-rust-remover-264-p.asp Quote Link to post Share on other sites
Keith66 Posted January 20, 2019 Author Report Share Posted January 20, 2019 ED, Cheers for that, did you get any brownish residue? Roger, as you can dilute Phosphoric acid (and most but maybe not all other acids) with water I can absolutly see the logic in rising with it. I have not idea if the same is applicable for petrol, maybe i need to do a little more research. Andrew, my understanding is that Phosphoric acid is a generic chemical that comes in varying concentrations, and its that which affects the rate of rust removal/conversion. So i used this one, https://www.ebay.co.uk/itm/Phosphoric-Acid-Descaler-Rust-Remover-45-Safe-On-Metal-Surfaces-5L/122394715228?hash=item1c7f4b245c:g:cVAAAOSwStdbGZd1:rk:1:pf:1&frcectupt=true It's £18 delivered for 5L of 45% solution which seems pretty effective. And i've no connection with them but did check the contact details and they do have a physical site where they say they do, well according to the pics on google streeview anyway. Cheers Keith Quote Link to post Share on other sites
RogerH Posted January 20, 2019 Report Share Posted January 20, 2019 Hi Keith, petrol is not a solvent of Phosy. But it would wash away any excess free standing Phosy. Roger Quote Link to post Share on other sites
ed_h Posted January 20, 2019 Report Share Posted January 20, 2019 Keith-- I find I get much less of the brown color if I rinse well, preferably with hot water. You are right--Phosphoric acid is a pretty generic chemical that is packaged and sold for a variety of specific uses. I buy it as a paint prep solution at a home center. I believe it is around 40% and goes for around $13/gallon. I usually dilute it at least 1:1 so it goes further. Ed Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.