Bought a spare petrol tank for my T3 off EBay and wanted to ensure it was clean and then sealed before painting and future use. Looked at options over the cleaning issue and decided on trying electrolysis.
Picture is of the second day’s rust collection. The first day was considerably worse, but I didn’t have a camera to hand. The anode is two bolts welded head to head together along with a bit of a ring spanner end to enlarge the area. The anode extends 12 cm into the full tank of water/sodium carbonate mixture. The cap is an old water thermostat cap that snugly fits over the petrol cap orifice and even has the correct sized cut away to fit over the fuel cap mounting.
Impressive results! Are you going to use a sealer, or just clean it out? If you’re going for a sealer, do you know of one that works well with E5/E10 petrol?
I cleaned out a rather crusty tank recently. I used a 8:1 water/molasses mix and left it in there for a month. After emptying and a good flush with clean water it was nice and shiny inside.
Plugged it in for a third day as anode still collecting rust and material. However, the raised section of the inner tank immediately under where the anode sits looks rust free and shiny so happy with the results so far.
I recently did a tank on a Lodola that was totally rusty inside and filling the floatbowl with flakes - I removed the rust with Evaporust from toolstation - then used Flowliner and a bung (as per Godfrey above) the results were excellent. A smooth white glass like finish.
I’ve always used vinegar followed by a trip to the car wash and then drying with a hair dryer. I never had good results with sealing and instead just start using the tank.
As the ethanol in modern fuels is a water magnet unless you keep the tank virtually full at all times to eliminate air and completely drain and dry store when not in use -then imo anyway a liner of some kind is virtually a necessity these days.