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Goggomobile
2nd Jul 2016, 07:18 AM
Workin on my fuel tank.

I blasted and painted it before I checked for leaks.

Im thinking of putting plain fuel in and looking for fuel seeping out.

Does anyone have any suggestions ?

Randal

Chris Parks
2nd Jul 2016, 08:04 PM
Does it look like it will leak, if not generally they won't. I had a tank that developed pin holes through all one side of it due to bad design so I emptied it and fibreglassed the corroded areas and it never leaked again while I owned the car. Petrol will sort out whether it has leaks and glassing any gets around welding the thing.

KBs PensNmore
2nd Jul 2016, 08:39 PM
Hi Randal,
How I used to test my tanks, when I made them, was to seal all the outlet/inlet points bar one, that had a T piece fitted that allowed for an airline fitting and a pressure release valve. Compressed air was pumped in at around 4 PSI, with the release valve set at 5 just for safety. Water with dishwashing liquid (about 1/4 cup to a litre) was sprayed/brushed onto the tank. Spray application was with spray bottle, windex type.Make sure that you check to bottom of the tank well, as that is where any rust is normally found. Should you find any leaks, they can be be soldered using a soldering iron, without any cause for concern, DO NOT USE NAKED FLAME on a soldering iron.
Kryn

bob ward
3rd Jul 2016, 10:02 AM
I'd go with the very low PSI air pressure test, another way to check for bubbles is to dunk the tank in a paddling pool or similar.

If the air pressure test is not feasible I would fill with water and check for leaks rather than petrol. That makes things safer if subsequent repairs are required.

jhovel
3rd Jul 2016, 04:13 PM
Water is a good test (small molecules) as long as you break the surface tension with some dish washing detergent!
I'd go with that, in case you need to do some subsequent welding, as Bod mentioned.

kwijibo99
3rd Jul 2016, 10:33 PM
G'day Randal,
It's probably best to check for leaks before painting the tank as the paint itself can act as a short term sealant and mask small leaks for a while. Also if there are leaks, fixing them will probably bugger your paint job anyway.

When repairing old soldered stationary engine fuel tanks I colour in the repaired area with a permanent marker then fill the tank with enough petrol to cover the repair. If there is any porosity whatsoever in the patch or seam the texta will run when it's exposed to even tiny amounts of petrol.

I find this method works well as there's no chance of getting water in the tank which then needs to be dried out and no risk of the tank approximating the shape of a sphere if you get the pressure wrong with the air compressor.

I also flush the tank with metho and purge with argon before soldering as igniting any residual fuel vapour can leave you with a spherical tank and no eye brows.
Cheers,
Greg.

Hunch
4th Jul 2016, 08:07 AM
There is a sloshing sealing compound available locally, can't remember the name but have a tin somewhere, for the simplest solution. If you want to weld, did some Ferrari pos alloy tanks with pin holes a while back, purged with exhaust gases, water was sufficient to identify, doesn't take much to dry em out. Steel tanks that have internal rust might need a few dozen nuts and bolts tossed inside and agitated for a fair while to salvage them, if you want to make sure you're not repairing a sieve and avoid repeats.

Goggomobile
4th Jul 2016, 03:59 PM
Guys
I did a quick Google on fuel tank sealing systems. There are a few that are available in Australia - PU,s and Epoxies.

Main in thing at the moment is to do some tests and see what I get.

The reason why I'm being a bit anal is the fuel tank sits over the engine in the rear of the car ... The one consultation is the fuel is a two stroke mix.

Randal

brianwynn
5th Jul 2016, 12:04 AM
Hey Randal, I think you should look into some red kote fuel tank liner I used it on a tractor fuel tank that was full of pinholes (washed it out with acetone first) and that was about 2 years ago haven't had a problem since Fuel Tank and Radiator Service - Red-KoteŽ - Fuel Tank Liner (http://ftrs.com.au/redkote/about.php)

Goggomobile
7th Jul 2016, 08:06 AM
Yep found it and a supplier on the GC. Looks like it's similar to some of those products used for radiators.

In the Red Kote blurb it mentions that a lot of inside rust is caused by moisture in the fuel. Treatments line the tank and stop moisture and I guess oxygen getting to the metal.I never really thought about it I must say


Will keep you posted. Many thanks. Ta. Randal