Petrol tank treatment

[pdg]

Got a bit of rust inside a petrol tank, would very much like it to not get worse...

Any recommendations for an internal treatment/sealant/goop that actually might work and can cope with ethanol?

Ta muchly.
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Any and all advice given should not be followed - if you have to ask it means you don't know so get a man in to do it for you.

[stinkwheel]

POR15. Full 3-part treatment which has a degreaser, etch and the paint itself. Scrupulously follow the instructions. Particularly with regard to totally and thoroughly drying it before putting the paint in.

Be warned, it does NOT come off stuff once it's set so don't spill and if you do, remove it before it dries. A mate did a trailer chassis with it then wanted to weld stuff on some years later. Couldn't get it off, not even with a wire brush in an angle grinder.

Don't be tempted to just use the paint without the pre-treatment.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[pdg]

I've heard mixed reviews on POR15, but that was 20+ years ago and it's highly likely they just tipped out the petrol and dumped the por in...

I do know someone that used a competing product - after a couple of months it looked like there was a screwed up carrier bag inside his tank where it had totally separated - that's the sort of thing I'd also quite like to avoid.

I may experiment with chemical rust removal first too - back in the days of 4* I would've left it at that but modern E* fuel is so hygroscopic it's almost certain to rust again quite quickly (especially as it's Chinese steel).

So, rust removal too - is evaporust really better than vinegar?
____________________
Any and all advice given should not be followed - if you have to ask it means you don't know so get a man in to do it for you.

[stinkwheel]

I've seen some remarkable results with deox-c.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[pdg]

[Ducked]

Ditto.

When it gets worse I'm thinking I'll probably just stop using the tank and put a plastic scooter tank in a top box.

I'm wondering if it might be possible to cut the top off the knackered tank and use it for storage, but probably easier and more space efficient just to make something more angular.

[Robby]

I've always used phosphoric acid. A litre bottle of that from amazon, topped up with warm water, then leave the tank for an hour or 4. That's all it takes.

However, phosphoric is unkind to everything that isn't steel. This includes rubber and aluminium alloy. So fuel tap, any kind of fuel sensor, in-tank filters and the like must be removed and any holes blanked off.

[jeremyr62]

If you are cheap and can afford to wait, fill the tank with water and add a tin of black treacle. Maybe throw a few steel nuts in. Leave it for a few weeks, shaking it up every so often. The rust will disappear but the uncorroded steel will be unaffected. This of course assumes the tank is off the bike.
The process is called chelation. There are commercial chelating products which will work much faster (Evaporust) but they are not cheap. I got rid of the rust inside a VF500 tank like this. I also did a very rusty VFR1200F centrestand. That took ages but all the rust went. For a thin walled petrol tank, chelation is good because it's such a gentle technique.