Gene Kearns wrote:
On Tue, 01 Jun 2004 10:38:25 -0400, DSK wrote:


K. Smith wrote:

The usual method to "test" is to;
(i) clamp all usual outlets at the end of their runs (that way you
test the unions taps etc),
(ii) fill with diesel or water,

WRONG

Do *not* fill a fuel tank with the wrong kind of fuel, or water. I think
most people would be smarter than to do this anyway, but I felt I should
speak up just in case.



Yep.... a really stupid idea. Here's a better way:

First, mix an indicator solution of:
1/2 Gal. distilled water
1/2 Gal denatured alcohol
15 grams of phenolphthalein powder

Take a large cloth that will absorb 3cc of household ammonia per cubic
foot of tank capacity. Stuff dampened cloth into the tank. Tank
should be empty, except for the ammonia rag.

Pressurize the tank to a VERY LOW pressure.... certainly not over 5
psi.... use good judgment.... drinking comes *later*.

Soak another cloth with the indicator solution and use it to
wipe/cover the tank. Leaks will show up as pink or red stains on the
indicator cloth.

Remove the ammonia cloth and either hit the bar or the bay.....


I know from experience not to even argue with Gene, who is a classic
case of older but no wiser, however I better go on the record:-)

Again, "Don't under any circumstances pressurise a 250 gal alloy fuel
tank to anything remotely like 5 psi of anything much less air!!!"

You will need a new tank if you do, but that'll be letting you off
light, you might need a new hull & deck or even an ambulance. Del would
work out the stored energy for us in a flash:-) Oops did I say flash:-)

Again there is only one correct way to test & it's simple, easy & cheap
so why not???? Yes you probably do need a new tank, but what if it's
just a leak in a connection etc .

Anyway tried to answer, wouldn't have had not someone suggested 3 psi
of air.

K

K. Smith wrote:
Again there is only one correct way to test & it's simple, easy &
cheap so why not????

If that's true, then why did you post a bunch of tripe about using water?

... Yes you probably do need a new tank, but what if
it's just a leak in a connection etc .

Anyway tried to answer, wouldn't have had not someone suggested 3
psi of air.

ABYC and ABS standards call for 2 ~ 2.5 psi IIRC. But that's for new
tanks & fuel systems.

Fair Skies
Doug King

JamesgangNC wrote:
Actually filling a tank with water is a comon way to test for leaks.
Particularly with large tanks where filling the tank with fuel can be costly
and dangerous. It's not like a large fuel tank doesn't get a little water
in it from time to time.

That last point is true, but that doesn't make it a good idea to
deliberately fill the tank with large amounts of water.

Frankly, if filling a tank with water is so common, how come there is no
mention of it whatever in either standards or in contractors handbook?
It seems to me that cleaning the tank afterwards would be more trouble.

Gene's phenolpthalein test is a lot more common in my experience,
although I haven't seen it done with large tanks which are usually air
tested after scrupulously gas freeing them.

Fair Skies
Doug King

Cleaning the tank afterwards is about the same for all these options. If
you fill it with water getting the vast majority of the water out is easy,
just syphon it out. It the last remaining water or whatever that is
trouble. I take the fuel gauge sender off so I can put a syphon all the way
to the bottom. Most pickups do not go to the bottom so that whatever water
or crud accumulates will not get picked up.

"DSK" wrote in message
...
JamesgangNC wrote:
Actually filling a tank with water is a comon way to test for leaks.
Particularly with large tanks where filling the tank with fuel can be
costly
and dangerous. It's not like a large fuel tank doesn't get a little
water
in it from time to time.

That last point is true, but that doesn't make it a good idea to
deliberately fill the tank with large amounts of water.

Frankly, if filling a tank with water is so common, how come there is no
mention of it whatever in either standards or in contractors handbook?
It seems to me that cleaning the tank afterwards would be more trouble.

Gene's phenolpthalein test is a lot more common in my experience,
although I haven't seen it done with large tanks which are usually air
tested after scrupulously gas freeing them.

Fair Skies
Doug King

That's interesting. Without knowing the source of the leak or the shape
of the tank and availability of a suitable poly replacement, your advice
is to junk the tank? Tony, please get a second opinion. It's a
30-yr-old boat, and you may only have a cracked hose.
Regards, Boatdreams.
--------------------------
Steve Lusardi wrote:
Tony,
Don't even bother. Throw it away before it kills you. Never use aluminum for
a fuel tank. It is far too reactive. Use polypropylene, it doesn't corrode.
It is stable. It resists vibration. and it doesn't generate static
electricity.
Steve
"Tony Abbott" wrote in message
om...

How does one check for a fuel tank leak? The boat is a 1974 33' Silverton
with an alumimun(?) gas tank under the cabin floor, 250 gallons. It is a
gasoline based boat.

Thanks for any and all responses.