Rust inside the fuel tank.

[thudpucker]

A little off topic, but still of interest to power boaters.

I've got a Rusty Tank from a B&S Pulsajet Carb, 5 hp.
There's so much rust inside the tank, it's flaking off and plugging the fuel orifices.

It's inside, impossible to reach.
I'm looking for Chemical rust eaters!
It seems that Molasses (1/10 with water) is almost the best, but Apple Cider Vinegar is good too.

What's your best guess?

 

[Mr Efficiency]

Well, news to me, molasses a rust "eater" ? How does that work ? If it really as rusted as all that, it can't be far off perforation, maybe you could fit a bladder of some kind inside it.

 

[thudpucker]

Molasses mixed 1 to 10 water. Let it set for a week maybe. So I'm told.

The Bladder would be a Tough thing to make/fit.
The Tank has two parts, one for fuel, and one smaller cup for the main jet to get it's fuel from.

I have fixed these with a Chain Saw filter for the main fuel pickup, and 'hand made' a small copper cup for the Main jet supply.

I was so proud of myself. Started on the first pull. But two years later, the flaky Rust had once again plugged up the tiny jets in the Carb.

If I could beat the Rust, I would have the engine back working in a short time without all that 'creating'....

 

[Mr Efficiency]

Molasses and petrol are compatible ? I'd have thought it would be like having "sugared" petrol.

 

[thudpucker]

Nope! The Molasses has to be completely washed out before using the tank.

To nite I see an "Electrolysis" method of turning the Rust to black Carbon. I'll look into that some time this week.

 

[Mr Efficiency]

You would like to coat the inside after neutralizing the rust, not sure what would work best though.

 

[thudpucker]

The Rust cannot be stopped unless you can keep Oxygen away from the Metal.
I've never heard of a Paint that will stop Rusting.

 

[Mr Efficiency]

I have to say I am impressed by how Penetrol keep rust at bay, but that is not going to be any good in contact with petrol. Iso-Polyester resin might do it, but vibration could be too much for straight resin, perhaps some milled fibres mixed in could give sufficient integrity to a first coat, and follow with straight resin for a second coat. Pour it in and tumble it round to get an even coat(s). If it is thick enough, should give a barrier to retard rust. Something in the epoxy or polyurethane family might be better, but you have to be sure it is neutral in contact with the fuel.

 

[Mr Efficiency]

What you really want is a thermo-plastic you can 'blow-mould" like a glass-blower, giving a lining to the void.

 

[thudpucker]

Yes that T-Plastic, Fuel/oil resistant stuff would be the correct answer.
If I could draw pictures I could show you the complicated part of this problem.

 

[dinoa]

Deactivate the rust then slosh with Proseal or one of these products http://www.aircraft-spruce.com/search/search.php

Dino

 

[NavalSArtichoke]

Nope! The Molasses has to be completely washed out before using the tank.

To nite I see an "Electrolysis" method of turning the Rust to black Carbon. I'll look into that some time this week.

Save your time (and possibly money).

Rust is oxidized iron from the steel. There is a tiny amount of carbon in the steel, but that's not what causes the rust. The only way you get rid of rust is to grind it/sand it off down to bare metal. There is no magic process to reverse the rust once it's created.

 

[thudpucker]

Yessir! That's what I recalled from Chemistry. But that was a long time ago and I was hoping for a minor miracle developed since then.

It looks like I'll scratch it out with sand or rocks and replace the Cup as I did before.
Thank you all for the replies.

 

[NavalSArtichoke]

There's a lot of chatter about this molasses thing on the web, but it reportedly takes a long time to work its magic (several weeks for heavily corroded items), and no one is too certain about how it works.

You can google "Molasses and rust" to find more discussions.

 

[Mr Efficiency]

Rust convertor changes rust into more stable compounds.