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.

Is there a strong smell of gasoline in the bilge? Could be a case of sloppy
fittings, but if you're leaking gasoline out of the tank in any quantity at all
it's going to smell pretty stong.

Do you have water in your bilge? Is there a petrochemical film on top?

What makes you suspect that you have a leaky tank?

Tony Abbott wrote:
How does one check for a fuel tank leak?

The best way is with air pressure (about 3 psi) and soap bubbles.
However, it's likely that you've got a tank partially full of gasoline,
which makes this impractical and potentiall dangerous.




... The boat is a 1974 33' Silverton
with an alumimun(?) gas tank under the cabin floor, 250 gallons. It is a
gasoline based boat.

The first thing to do is clear as much access to that tank, and the
bilge around it, as you can. Get all the water out, use a sponge and
then paper towels. If you can't dry this part of the bilge, partition it
off with some plumbers putty. After sopping up all bilgewater and fuel,
wait a while and see if more fuel appears. If yes, then track it down.

Fair Skies
Doug King

The boat is sitting on stands (thought I was at the end of a restoration
project)... all fittings are dry... caused a change of pressure to the
fuel tank moving a pipe for the fuel fill trying to remove the old fill
hose... top and side of tank are dry... we started the day, a rainy day, we
thought we'd finish assembling the engines but not a chance... no gas
fumes... started cleaning and organizing as only a few weekends left till
having her picked up for return to the sea... old, deteriorating fuel fill
hose needs replacing so I went to remove the hose... it would not budge...
but I caused a pressure change in the tank...

Me thinks (scary thought after a few tequila shots to get over this
discovery) the pressure change shifted some sediment over a hole and thus
the leak...

So a clean bidge with some clean water then became topped with petrolium...
thus the though there is a leak in the big tank under a finished floor...
thus the need to figure out how to test it to confirm and also the need to
drink more...



"Gould 0738" wrote in message
...
Is there a strong smell of gasoline in the bilge? Could be a case of
sloppy
fittings, but if you're leaking gasoline out of the tank in any quantity
at all
it's going to smell pretty stong.

Do you have water in your bilge? Is there a petrochemical film on top?

What makes you suspect that you have a leaky tank?

Tony Abbott wrote:
The boat is sitting on stands (thought I was at the end of a restoration
project)... all fittings are dry... caused a change of pressure to the
fuel tank moving a pipe for the fuel fill trying to remove the old fill
hose... top and side of tank are dry... we started the day, a rainy day, we
thought we'd finish assembling the engines but not a chance... no gas
fumes... started cleaning and organizing as only a few weekends left till
having her picked up for return to the sea... old, deteriorating fuel fill
hose needs replacing so I went to remove the hose... it would not budge...
but I caused a pressure change in the tank...

Me thinks (scary thought after a few tequila shots to get over this
discovery) the pressure change shifted some sediment over a hole and thus
the leak...

So a clean bidge with some clean water then became topped with petrolium...
thus the though there is a leak in the big tank under a finished floor...
thus the need to figure out how to test it to confirm and also the need to
drink more...


Being petrol it's a bit scary bananas & you don't say how much is in
the tank.

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,
(iii) have a small diam hose clamped to the fill or even the vent,
(iv) lift it 2ft above the top of the tank (=1 psi),
(v) top it up, mark the level at 2 ft up then
(vi) see if it's level drops over a short time.

Also once a light positive pressure is there, you can look around
accessible areas for leaks (notoriously difficult small leaks can
capillary a long way before becoming apparent/a drip).

Being petrol & the boat being on stands you can probably syphon what's
in there out pretty easily into 205 ltr drums.

Testing non pressure designed containers with air is always dangerous,
more so even than using petrol as the test liquid; also it's very
difficult to "limit" very low air pressure, particularly suggested don't
give the tank 3psi, it'll be creaking & groaning with a liquid head
pressure of 2 ft (1 psi).

The USL code for commercial boats, forbids testing with more than a 4
ft head (2psi), because rather than looking for leaks you'll be creating
them:-) or damaging the baffles/hull/decks as the tank bulges.

K


"Gould 0738" wrote in message
...

Is there a strong smell of gasoline in the bilge? Could be a case of

sloppy

fittings, but if you're leaking gasoline out of the tank in any quantity

at all

it's going to smell pretty stong.

Do you have water in your bilge? Is there a petrochemical film on top?

What makes you suspect that you have a leaky tank?

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.

Note to rec.boats regulars- I generally skip K.Smith's posts but checked
this one.

DSK

I agree with Doug.
I just had to replace my gas tank. Had to cut away fiberglass to do it, but
much better than an explosion. If you do want to pressure test it first,
make sure you plan not to use the boat for at least a few days, find a way
to drain the tank, test it, then open everything the fumes could possibly
get into and air it out well. Also wash the inside of the boat, around the
fuel tank area with purple stuff (available at any parts store), and rinse
it very, very well. Wait a day or so before going back onto the boat. If you
smell fuel, do it again. I can't express to you enough just how dangerous a
leaking fuel tank or low lying fumes can be.
Joe


"DSK" wrote in message
.. .
Tony Abbott wrote:
How does one check for a fuel tank leak?

The best way is with air pressure (about 3 psi) and soap bubbles.
However, it's likely that you've got a tank partially full of gasoline,
which makes this impractical and potentiall dangerous.




... The boat is a 1974 33' Silverton
with an alumimun(?) gas tank under the cabin floor, 250 gallons. It is a
gasoline based boat.

The first thing to do is clear as much access to that tank, and the
bilge around it, as you can. Get all the water out, use a sponge and
then paper towels. If you can't dry this part of the bilge, partition it
off with some plumbers putty. After sopping up all bilgewater and fuel,
wait a while and see if more fuel appears. If yes, then track it down.

Fair Skies
Doug King

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.

"DSK" wrote in message
...
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.

Note to rec.boats regulars- I generally skip K.Smith's posts but checked
this one.

DSK

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.

You make a fair point. If it is leaking it would probably be a waste of
time fixing it. If the leak is due to corrosion then it's probably about to
leak in a bunch of places.

"Steve Lusardi" wrote in message
...
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.