Testing fuel tank for leaks; alternative methods?

[mhorowit]

I've got the wing tank on the back porch with a condom over the input, a plug on the output (since I couldn't find a schrader valve) and I've inflated the condom by blowing into the drain valve. The condom collapses after about :05.

I've pressurized the tank slightly, coated it with soap bubbles but am unable to locate a leak

My A&P suggests simply filling the tank with kerosene and looking for a leak, but what would I then do with 6 gallons of slightly used kero?

Any reason I can't fill the tank with water for several hours, look for drips, then drain the water out? Then slosh with kero or (as in another thread) alcohol?
What's the harm? - Mike

[Marv]

Re: Testing fuel tank for leaks; alternative methods?

Mike for one thing, kerosene will go through a hole that water will not. The kerosine residue will mix with the avgas and not hurt anything. Use the kerosine to start your charcoal for your grill instead of lighter fluid. Marv

[Hank Jarrett]

Re: Testing fuel tank for leaks; alternative methods?

You could probably pour the Kerosine through a paint or coffee filter to remove any solids and use it in a heater. The one in my hangar seems to burn absolutly FILTHY Kerosine with no problem at all. I wouldn't use it on a BBQ. Makes the burgers taste awful.
Hank

If you can get some fuel dye it will make the leak easier to see. Don't try to weld the tank yourself, a radiator shop should have the right equipment and know how to purge the fuel fumes so there isn't an "incident".

[Len Petterson]

Re: Testing fuel tank for leaks; alternative methods?

Soap and water and low pressure make shure you can blow bubbles with soap mixture.
My Ai used the differential compression tester it has a small orfice so the volume of air is low and if you slowly increas the pressure seting from 0 to 5 psi or more( on the output gauge , mayby you will find the leak. what is with the wented cap on so the air can escape 5 psi in the tank will Blow It Up like ballon!
The condome test is the safest for the tank Kerosen will go through VERY small holes so will alcohol ( Methyl hydrate) You may not need to fill it full just lay it over to one side at the time. Food coloring works in hydrualic systems but I have never tried it on fuel tanks. Maybe?
Len

[Robert Lees]

Re: Testing fuel tank for leaks; alternative methods?

I hope you're using good quality condoms! 1% of protected "conjunctions" end up with a surprise.

[Gary Snell]

Re: Testing fuel tank for leaks; alternative methods?

I checked my tank recently using the air/condom method. You don't need a schrader valve. With a regulator in your air supply and a small hole in your condom, you can maintain a small positive pressure in tank. Simply put a male quick disconnect fitting in the drain port to attach your air coupling, condomize the filler opening, and plug the rear fitting. You can them take your time looking for the bubbles. Don't make the mistake I did by installing the tank without a good thorough leak test.

[Pearson]

Re: Testing fuel tank for leaks; alternative methods?

The guy that welded up my wing tanks used an inert gas to check for leaks. I forget EXACTLY how he did it, or the gas he used. I think he filled the tank with the inert gas (not under pressure), to expel any gas fumes. Then he ran a flame around the outside of the tank at all the seems. It seems like maybe he could tell where a leak was because it blew the flame out or something like that. I can call him on Monday for details if you like. Let me know. Or maybe someone on here has heard of what I am referring to. Hank??? Anyone???

[Hank Jarrett]

Re: Testing fuel tank for leaks; alternative methods?

There are sniffers for Freon and natural gas that would work to look for a small leak. Problem is I wouldn't want to mess with a fuel tank filled with low pressure gas and it's illegal to intentionally release freon. Seems to me I would still try Kerosene with dye if it was mine.
One other thing is the condom trick works GREAT, but don't get petroleum products like kerosene directly on the condom. The latex in the condom will melt. I guess you could use the more expensive "organic" condoms.
I suppose when they made the condom in the first place the manufacturer didn't plan on getting fuel on them.

KINKY!
Hank

[dewhitaker]

Re: Testing fuel tank for leaks; alternative methods?

Mike, since you have the tank out, this may work well for you. I have used this method on other types of tanks.

1) Seal the openings in the tank.
2) Pressurize the tank, 1 lb. air, careful! Don't blow it up.
3) Immerse the tank in a large barrell of water, the bathtub, whatever it will fit in.
4) You should be able to see air bubbles in the water.

Hope this helps!

[mhorowit]

Re: Testing fuel tank for leaks; alternative methods?

Folks - thanks for all the suggestions.
I put two gallons of kero in the tank and let the tank sit on each side (except the top and one side) for an hour each. The only leak was at the drain because someone had placed a too large O ring around the stem.
Now I have a fine layer of kero over the flagstones around the workshed; - Mike