Fuel tank internal corrosion - 3CL

Laverdaton

Laverdaton

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In the garage deciding what to do first!
I've been stripping the paint from tank today and shining a torch in through the filler neck just made me realise how rusty it is inside. Externally, there are no signs of a fuel leak along the seams, but internally there is a lot of flaky, shiny looking corrosion compatible with a bike that's been standing for years and years.

Before the respray should I get it vapour blasted internally and then treat with POR-15?

or, well.......I don't know else to do..............over to the forum junkies........
 
Laverdaton, highly recommended and used by a lot of people here is Caswell's Evapo-Rust, http://www.caswellplating.com/aids/evaporust.html. I haven't derusted my "spare" tank yet but I did buy some of it, derusted some phosphated tools I've had getting progressively rustier for 30 years. It removes rust brilliantly. It doesn't leave shiny bare metal, phosphoric acid will do that but it also removes a lot of unrusted metal in the process, not a good idea with already thinner than original sheet steel.
And Caswell's also has a fuel tank internal sealer that's supposed to be the duck's nuts with ethanol-added fuel, http://www.caswellplating.com/aids/epoxygas.htm. Nobody here has come up and said they've had problems with it, and plenty of people have talked about problems with other products.
Remember, if you do derust your tank, it will start to rust again immediately as soon as you've finished the process. The Caswell's anti-rust stuff even leaves a rust-proof coating. Check the archives, there were several threads on this a while ago.

Ken
 
I removed excess rust from my tank using pea gravel you can do it turning it manually or if you protect the tank correctly you can lodge it in a cement mixer as my friend did with great results . I used Por 15 9 years ago with perfect results
Regards
Tetley
 
As per the Caswell instructions I used a large handful of drywall screws[coarse threaded,sharp,pointy things] and acetone to clean my tank and it did a wonderful job. The bonus to using the screws is being able to remove them with a magnet.
 
One part Molasses to three parts water, mixed together and poured into the tank filled to the top of filler. Place the tank in the sun to warm the 'brew' for 3 to 4 days(longer if the rust is really bad, but solution can stay in the tank until all rust is removed, forever if you like, no harm will be done to the steel), remove Molasses solution, and rinse out with garden hose. Dry the tank with a hair dryer, and put in a litre or two of diesel(stops the flash rust) and slosh around and then remove.  You won`t have a scrap of rust left, the tank will be as clean as  a whistle, won`t eat metal, and doesn`t damage your paint. Cheap and best way to clean any rusted steel, tanks especially, but don`t use it to clean alloys. Solution can be used over and over again. Hope this helps, come on, be game, you will be surpised at the results :D.
 
Caswell is the "ducks nuts", it is the only sealer I trust to not be affected by modern fuel ethanol levels. I cleaned two tanks with several handfuls of small drywall screws inserted and manipulated the tank for several days. It scoured out whatever was loose inside. You I used a citrus based product called "Rusteco" which removed all internal corrosion and left the inside clean, shiney metal. It does not attached the metal itself. I then cleaned out the inside with Simple Green, allowed to dry, then Caswelled the inside. Caswell sells its product in a size that it states will treat "two 5 gallon tanks", however to insure full coverage I would use the entire contents for one tank. On a Norton Commando Fastback tank, this left a small amount of excess, however it also provided for a generous coating on the inside. Better too much than too little.
 
The Caswell Plating stuff is generally excellent, but be aware that you should buy new stock only.

Some time ago, my tank was somewhat less than perfect inside, so I sent it off to be done.  It came back looking perfect and a pound or so heavier, with what looked like a semi-clear epxoy skin on the inside - exactly what I expected & hoped for. 

However, what I neither expected nor hoped for was that it would subsequently peel off, leaving what looked & felt like a hard and opaque liner, one size smaller than the tank.  Apparently, Caswell released a bad batch, most of which was recovered before being used.

It was redone for free, and hopefully all is now well.  We'll see...

Alex
 
I too have used the pea gravel tank in the cemnt mixer trick to great effect followed by Trimite Deruster 25 http://shop.trimite.com/Deoxidisers/Derusters/t-deruster-25-1kg. It requires dillution so go's a long way and gives excellent results . However I get it from work on the sly which is it's main attraction . Once you've got the rust out , leak check the tank there's no point in sealing it if you dont have to. If your going to leave it with half a tank of stale fuel over winter then prob best to seal. The Molasses trick sounds great I shall try that one day when the bloody sun comes out .
 
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