"Roger Long" wrote in
:

Not enough for a proper inspection plate. Strictly speaking, the bolt
holes should not penetrate the tank. Either blind holes in a thick
ring or a flange that stands up above the tank like this:

http://home.maine.rr.com/rlma/Stride...tem.htm#FOtank

so that the holes don't open into the tank is the way to go. The
lower flange on the tank in the picture was epoxied down and glass and
epoxy run over the top of the flange when it was put into place.

I'll confess to having some blind holes in the cover since the tank
gauge is installed that way. Since the gauge is up in the raised
cover, I decided I could live with it.

I would have a ring (or square as the case may be) made to the outside
dimensions of the cover and the inside dimensions of the opening. It
should be 1 1/2 to 2 times the thickness of the bolt diameter. Drill
and tap to fit the current bolt pattern and drill and tap in between
for the cover machine screws. Fasten down over a gasket with short
machine screws inserted from the bottom. You'll have to shorten the
machine screws so they end up flush when taken up. The machine screws
that hold the cover down will then be going into blind holes. The
upper gasket will seal off any leakage up through the screws that hold
the frame and the lower gasket will indent enough to let the cover
screws compress the upper gasket. If you pick the right thickness for
the ring material, allowing for gasket compression, you may be able to
avoid cutting any screws.

It's a day's work but aluminum is easy to work. It may not be
necessary to go to these lengths with your particular tank
installation but, if it is a tank that can have some head on it such
as being over filled up into the vent and fill pipe, it may be the
only way to be sure it will stay tight. Getting my tank gauge tight
with the two or three feet of test head on it letting my upper tank
siphon fill the lower brought me pretty close to stripping the
threads. Diesel is runny stuff. I got my whole system tight and
pressure tested in the cold weather and lots of things started leaking
again as soon as it warmed up.

--
Roger Long

Roger,

I think that you've got too much time on your hands. Spending a day+
resolving a minor seepage problem isn't worth my time. I realize that
your fuel system is a labor of love, but it's not mine.

Personally I think that just retapping the 2 holes for larger screws
will solve the problem. The rest of the screws are just fine and have
held for 10 years. I have plenty of other work to do and hope to get
out cruising soon.

-- Geoff
www.GeoffSchultz.org