Rusty Petrol Tank - inside

[Stevie1262]

Cheers for info ...living in Scotland we don’t come across molasses much 😉....tank cleaned up with salt and vinegar mix and a rattle with nuts and bolts but bubbles appeared on the paint (two pack acrylic yuk!) which disappeared when it was dry so pinholes on top of the tank.....due to this I’ll go for POR15 to clean and seal ...tempted to strip paint of and just use enamel but the paint is looking more aged now so I’ll leave well alone ...great Forum many thanks

[Butch (cb)]

I had a tank powder coated some time back. Turned out there had been a liner within – no idea what. Whilst in the oven (no idea what temp they use for powder coating) the liner reduced to a whole bunch of what looked like uncooked prawn crackers – all detached and rattling around in the bottom of the tank. The tank had an anti-surge tunnel down from the filler cap opening so I had hell and all trouble getting them out.

[Colsbeeza]

I sometimes wonder why there are still many original tanks around over the last 70 years, used for years before Tank Lining Muck was invented. Perhaps they were ridden every day back then, so fuel was replaced very often.
I opted not to line my new tank, after reading all the horror stories of tank lining coming adrift. After chroming, I washed it out thoroughly, dried it in the sun all day, then rolled a couple of litres of sump oil around, drained it and stored it for about 12 months before getting the painting done.
So was that successful - Well No! - there is quite a bit of flaky rust though. The tap strainers seem to be catching all of it sofar. The Carb Banjo strainer doesn't seem to get any in it.
My strategy now is to keep the tank full of fuel to reduce condensation from cold nights, and run Octane 95 with no ethanol and fewer modern additives. I do ad Fuel Stabiliser though after recommendation from a local experienced motorcycle racer.
Colin

[Colsbeeza]

On the subject of molasses, I stripped all the rust from my BSA bits 20+ years ago. It was an English bike imported by me, and had seen its share of salt roads over the years.
Scrape and wire brush any oysters off, make sure there is only light surface rust remaining and then immerse completely for about 3 weeks. I would pull it out occasionally to check progress, and rub any bits which were a bit slower cleaning up than the others.
It would eventually come out spotlessly free of rust, but would go brown under your eyes in seconds. Very necessary then to passivate it quickly - under the tap, then wipe over with a weak alkaline solution, then light sand dry and undercoat ASAP.
My mixture was 10% molasses, 90% water. I had a large 135 litre plastic tub which would drown the mudguards (fenders), and about every two weeks had to scrape off a 1" layer of mould. The mould did not affect the bath performance.  A 20 litre drum of molasses goes a long way.
The Molasses solution is a little acidic, about the same as lemon juice.
The mudguards emerged with a definite lacey see-through look about them requiring quite a bit of patching, welding etc, and lots of finishing time, but I was able to retain the original parts.
The mixture does not attack the parent metal, and that is the beauty of using Molasses.
Colin

[Worty]

When I restored my first bike, 1959 BMW R60/1, it had been standing in an old lady's chicken shed for ca. 10 years.  The tank was obviously quite rusty.  Back then, I simply sloshed some petrol around, got it painted and ran it for the next six years without touching it before selling it on.  With the GF, that had also been standing some 10 years in a garage.  I used petrol plus old nuts and bolts before painting and using.  I checked the taps after two years and only a tiny bit of rust on the gauzes.  I suppose my philosophy is that the tank will probably outlast me.  If it doesn't, I'll get it repaired or replace it.

[coater87]

 The "greener" large restoration shops near me use molasses.

 This is not a toxic shite concoction that kills all the plants for a 50 foot circle. It does not burn emloyees, it does not harm the base metal, it is not expensive and it is very effective.

 The only down side is the speed of it.

 If you opt for a real chemical dip and rinse, the sheet metal tub can be back stripped bare in 3 days. It costs 10 times more because the chemicals are finite, and someone has to pay to ship them off as toxic waste. They say this does not effect the base metal, but I have seen some results that make me a skeptic about that.

 Lee