[C320-list] Leaky fuel tank?

[Marek Fluder]

​Guy,

Thank you for sharing your experience.
I have determined at this point that the tank is not at fault - put 5 gal
of diesel in it, pressurized then checked placing the tank on all sides
(excluding the top, but I do not anticipate this scenario...)
I have to settle for the conclusion that you came to  - it will remain a
mystery.
I feel that most likely the cause in my case was one of the hose-tank
connections leaking when the boat is heeled substantially and the tank
could shift a bit putting the strain on it.
My tank had only about about 5 gallons in it when I observed this, so
overfilling was not the culprit.
One benefit out of this exercise was learning that my fuel gauge shows 1/2
full with 5 gallons left...

Kind regards,
Marek
2005 #1028


​

On Wed, Jun 22, 2016 at 2:36 PM, Guy Smith <smitski2001 at yahoo.com> wrote:

>
> Hey Marek!
> I feel your confusion.I had a similar problem last season with Pleiades, a
> '97 #452. The evidence of a leak was traced to the same area that you saw
> pooling. I pulled the tank over the winter and had it inspected and
> pressure checked with the sending unit still in it. All was good with the
> tank. Since the pooling was under the tank, the only other culprits could
> be the fill and vent lines which are smooth connection fittings or the fuel
> lines, which are barbed. Since it was winter and I didn't pay attention to
> how secure the rubber lines were attached when I took them off (it was
> cold!), I assumed that it was some connection to the tank or faulty
> hoses. I do remember over filling the tank to where the fuel bubbled out of
> the vent during a fill, so I may have had fuel in the rubber fill and vent
> hoses for a time until the fuel level decreased. It may have seeped out
> then. I inspected the hoses and did not find a smoking gun, replaced some
> and put it all back together. I'll keep an eye on it now, but I do still
> wonder what it was. Sometimes you just have to call it a mystery I
> suppose.  I also noticed that the tank was not sitting flush on the hull in
> the foot frame, so there may have been some rocking working on the hoses. I
> corrected that issue with some well placed rubber pads before cinching it
> back down.
> I also added a diesel/air fuel separator while I was crawling around in
> the locker. Much easier with the tank out. Now the vent should not burp
> diesel during fills.
> Fuel/Air separator
>
> Sorry if this doesn't help. Sometimes you just need to hear from someone
> who commiserates... :)
> Regards,~guy
> Pleiades'97 C320  #452Worton Creek, MD
>
>
>       From: Marek Fluder <marekf at gmail.com>
>  To: "C320-List at Catalina320.com" <C320-List at catalina320.com>
>  Sent: Wednesday, June 22, 2016 9:21 AM
>  Subject: Re: [C320-list] Leaky fuel tank?
>
> Rick,
>
> Thank you for your advice.
> Fuel was pooling at the lowest (forward port) corner of the tank before
> overflowing the foot-frame that secures the tank in place.
> In the past I have sealed my leaky sender unit on the top of the tank
> (another common issue).
> This time I did not see any evidence of any leaks from the fittings, hoses
> and the side walls therefore I concluded it must be the corner or the
> bottom where I cannot see without pulling the tank.
> I have snapped some pictures.
> <http://www.catalina320.com/mediagallery/album.php?aid=297&page=1>
> Your idea of pressurizing the tank partially filled is going to be my next
> step.
> I would like to have a clear evidence before dropping close to $1000CAD for
> a new tank...
>
> Thanks again.
>
> Marek
> 2005 #1028
>
> On Wed, Jun 22, 2016 at 7:56 AM, Rick <rsulewski at bex.net> wrote:
>
> > Mark,
> > I replaced my tank a year ago because I had experienced a nasty sender
> > leak over the winter from an overfilled tank and did not want to endure
> > another fuel clean up mess over in the next several years given the age
> of
> > my hull (20 years) when the tank could be expected to begin leaking.  My
> > reasoning was  why wait for a fuel leak that day was predictable?
> >
> > Based on my research of aluminum tank leaks across several manufacturers
> > most diesel aluminum tanks can be expected to develop leaks within plus
> or
> > minus 5 years of the 20th year.....a matter of not if, but when the tank
> > can be expected to leak.  My review of the 320 discussion list pointed
> > toward many 320 tank leaks occurring at the lowest portion of the tank's
> > seam weld or the lowest portion of the wall nearest the tank's welded
> edge
> > near the forward & portside corner area.
> >
> > Did you see any evidence of fuel residue in the suspected area of the
> > typical 320 tank leak? Have you considered pressurizing the tank with a
> > small portion of fuel in the tank? Given the 320 discussion list tank
> leak
> > details I observed, owners seem to report evidence of tanks weeping well
> > before the leaks growing worse over time.
> >
> > When I received my new tank, the tank's fuel filler hose was securely
> > sealed with a flexible cup like cover that was pushed onto the filler
> inlet
> > that could also be clamped to that fitting. Also, all of valves were
> > closed. When I opened a valve I could clearly hear the air pressure
> > equalizing within the tank, suggesting that the tank was still under
> > pressure when it left the factory, perhaps due to the temperature
> > differences from when it was packed or the elevation differences from
> when
> > & where I am located. This suggested to me that the variables involved in
> > pressurizing the tank where tightly controlled by the tank's sealed
> valves
> > and the filler pipe seal and that the tank was still under several PSI
> for
> > a sustained time.  That is why I suggest attempting to replicate the tank
> > weeping with a small amount of fuel in the tank for a period of time
> while
> > the tank is left under pressure vs. simply looking for an air leak bubble
> > with soapy water.
> > Rick
> > 1995 320 hull #277
> >
> >
> >
> > -----Original Message-----
> > From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On
> > Behalf Of Marek Fluder
> > Sent: Tuesday, June 21, 2016 9:30 PM
> > To: C320-List at Catalina320.com
> > Subject: [C320-list] Leaky fuel tank?
> >
> > I have pulled my diesel tank today for inspection based on research on
> > this list archive and my observations of diesel showing up in bilge area
> > and around the tank. All fittings and sender unit on top were dry. Now I
> am
> > puzzled as I pressure tested the tank spraying soapy water and nothing.
> The
> > tank looks solid. Question to listers that replaced the tank - was the
> leak
> > on the tank obvious?
> > I am stumped.
> > Marek
> > 2005 #1028
> >
> >
>
>
>
>