Fuel tank sealants

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RTR
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Fuel tank sealants

Postby RTR » Thu Nov 28, 2019 6:32 pm

Has anyone used any of those products where you slosh the stuff around inside your leaking tank and it seals the leak? I am a bit doubtful whether this stuff works or just creates a big mess inside the tank.



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Re: Fuel tank sealants

Postby jhovel » Sun Dec 01, 2019 12:41 pm

I've used several different brands, successfully long-term.
The issue is however that the tank needs to be PERFECTLY clean inside! This is usually achieved with thorough mechanical derusting if required - e.g. fill with gravel, wrap in thick blanket or bubblewrap and put in cement mixer for a couple of hours. Then an acid wash with hot citric acid, then neutralising with baking powder in boiling water and thorough FAST drying with compressed air and removing water vapour and droplets in crevices with metho sloshing and re-drying with compressed air.
Then pour in the liner according to instructions. "Sloshing" it is not quite the right term, because it is not that runny - you sort of tumble the tank slowly until it has cover all surfaces, run into all nooks and you cannot see ANY metal surface any more. Mirror or endoscope IS required to confirm this.
Then put into a position where the lining can run out again over a period of time.
I've pulled the cork plug I had made out of the fuel tap hole at this stage and let it run out of there.
Once it stop dripping, wipe the fuel tap hole with a bit of thinners to reduce the thickness of the coating there enough to get the tap back in without chipping the lining.

The cause for failure is inevitably leaving surface rust behind somewhere. That then slowly creeps under the lining and lifts it off in flakes...

Cheers,
Joe



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Re: Fuel tank sealants

Postby David Lahey » Sun Dec 01, 2019 7:17 pm

Things to consider about lining tanks:
The epoxy type liners will work well on rusty steel tanks but you had better not dent the tank afterwards or it will crack the lining and with the liner in there you can't use heat to pull the dent out and it will need relining which adds a fair bit of weight each time you do it.
It works great on old fibreglass tanks because epoxy liners are about the same stiffness as fibreglass.
It's not a good idea to use epoxy liners on plastic tanks because they are very different in stiffness and epoxy doesn't stick well to HDPE so a mild bump will crack the liner.
I've done many old spanish fibreglass fuel tanks with low viscosity epoxy resin, first one being about 20 years ago and they are all still going well (and I leave the petrol in them continuously).
As jhovel says though, preparation of the tank before lining is critical to success. For fibreglass tanks I wash out all the premix residue with kerosene (inside and outside and any cracked or leaking areas), then hot dishwashing solution then dry it completely then a very quick rinse with acetone then dry it. I use brushing grade epoxy resin bought from a marine supplier. It is the thinnest viscosity epoxy I can get. The less you leave inside the tank the less the additional weight.


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The Hell Team
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Re: Fuel tank sealants

Postby The Hell Team » Mon Dec 02, 2019 8:13 am

As the previous respondents said a lot is the preparation. But after doing A LOT of glass tanks over the years, there is a difference in brands as well. I have had very good results with Caswell's lining products.It's an epoxy sealant and is straight forward to use. Clean and dry tank, mix the two parts and pour into the tank, moving it around to cover all internal areas. Pour off excess and leave to cure.
Just don't be in a hurry when you decide to do it. The prep takes ages, and the coating isn't a five minute job either. Done properly it leaves a strong liner that will last for ages.


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Jools
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Re: Fuel tank sealants

Postby Jools » Tue Dec 03, 2019 11:09 am

But if your 'liner' ever fails (and it will one day) it'll be an absolute nightmare to clean out completely.
IMHO... Silver Solder repairs, flush it out thoroughly, add a fuel filter.



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Re: Fuel tank sealants

Postby David Lahey » Tue Dec 03, 2019 8:00 pm

Jools wrote:But if your 'liner' ever fails (and it will one day) it'll be an absolute nightmare to clean out completely.
IMHO... Silver Solder repairs, flush it out thoroughly, add a fuel filter.

I bought a steel TY250 tank recently and a previous owner had (successfully) used soft solder on some tiny rust holes which is probably more sensible than what I tried on a friend's (very rusty) steel KT250 tank. I dissolved the rust with phosphoric acid, then used tobin bronze, which sealed each hole that I was working on at the time, but the process caused multiple new holes to form nearby. It also caused the flat sides of the tank to distort. After 4 hours work and making the tank much heavier and bent, I gave up.


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Re: Fuel tank sealants

Postby whitehillbilly » Tue Dec 03, 2019 8:29 pm

I did my Greeves tank with a sealant 20 yrs ago.
Bee Knees stuff at the Time. Now just crumbling, every 12 months, jar of nuts and bolts poured in and shaken, to remove flaking.
Fergy Tank was a soldered up, by local 'old school' radiator shop, 18 years and no problems. Hope the Series 3 landy tank lasts soldered.

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Re: Fuel tank sealants

Postby tat ty » Tue Dec 03, 2019 8:57 pm

In my time I have bought a few good quality tanks with (photographically) minor rust inside.

Expensive yes; but I have quite a few lined up and so far have yet to replace the original.

Soak them in molasses for 12 months and some.

Reckon they will see me out and the next couple of custodians as well.

Just a thought.

Alastair



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Re: Fuel tank sealants

Postby RTR » Thu Dec 05, 2019 7:53 am

Some great advice here so far.
Molasses? That's an interesting idea but I don't really understand. How does this work?



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Re: Fuel tank sealants

Postby David Lahey » Thu Dec 05, 2019 6:01 pm

RTR wrote:Some great advice here so far.
Molasses? That's an interesting idea but I don't really understand. How does this work?

Molasses contains acids that eat the rust and leave the steel alone. Pepsi or Coke will do similar but are more expensive


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