Help with fuel tank mounting and pressure testing

[Jimmy H.]

Hi, the previous owner of my boat had removed the deck, tank, stingers, etc... and I haven't seen this exact one mounted before. It does have brackets on each side so I'm thinking I can just glass in two boards under the mounts like in the picture and call it a day. It would have no real contact with anything to prevent moisture and corrosion. Thought?

As well how could I go about pressure testing it? I think 3 psi is the number to test with but what type of gauge and which do I connect it too and getting the air in then sealing it without air getting out?? The pic below shows one threaded fitting and two hose with clamp fittings. It is 4' in length and holds 20 gallons.

Thanks!!

The wood piece would be different and it would "float" slightly off the hull with PB.

Tank cleaned up nice, can it be pressure tested easy?

 

[Streetgang]

Re: Help with fuel tank mounting and pressure testing

Well as it turns out mfg and testing tanks is what we do every day...so lets walk thru this.

I will assume that the internals of the tank are sound and we can go forward,,,but it that isnt true then stop right here.

Testing, is nothing more than sealing up the threaded fittings, and the flanged pipes with rubber stoppers. You can find these easily through McMaster or the equivalent in your neck of the woods. 3 or 6 max psi (US) is outer limits. The real trick is to use windex to spray onto the weld seams let alone all over the tank and then patiently watch for bubbles.

So if that all goes well you have a good chance to go forward, but I want to warn that all this is for naught if the internals are crapola.

As best you can determine what is tank material ? aluminum, galvanized ?? Year of boat ?

Good luck and hope this helps.

 

[Jimmy H.]

Re: Help with fuel tank mounting and pressure testing

Well I have no idea how the internals are. I do know I had some fuel in the tank when I first got the boat and the gauge on the cluster read properly as far as I could tell. I assume then the sender may work ok but other than that??? I work at an auto dealer and I know some guys have a borescope I could use to take a look with. Would that be the right idea to check the internals?
The tank is aluminum and not galvanized, year of the boat is 1986 and the stamp on the tank shows it was tested/inspected in 1985.
Anything else I can do?

 

[Jimmy H.]

Re: Help with fuel tank mounting and pressure testing

I checked the tank internals last night and looks great inside. If the pressure test passes today/tonight then I woudl like to install it this weekend. Any thoughts on just having it attached to the two mounts front and back only. Nothing supporting it anywhere else. Again it is a 28 year old aluminum, 18" wide, 48" length, about 7-8" tall and 18 gallon capacity.
Thanks!

 

[mxcobra]

Re: Help with fuel tank mounting and pressure testing

mabie? mount tho board like you said. Use foam to hold it in place....

 

[jigngrub]

Re: Help with fuel tank mounting and pressure testing

Your tank should be installed like this:

Installed between stringers with bulkheads for and aft, stringers and bulkheads fiberglassed to the hull for a watertight compartment in case you tank develops a leak so your bilge won't fill with fuel.

The tank has to be bedded in with expanding urethane foam to support it and to prevent movement.
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In the picture below there is not enough clearance between the top of the tank and the bottom on the decking for hoses and connections.

 

[Jimmy H.]

Re: Help with fuel tank mounting and pressure testing

Thanks Jig,
I did want some expanding foam but the more I read it seemed that a lot of re-builds weren't using it so not to trap moisture between it in the tank. I want and will use it though so it is very secure. Also I'd like to enclose the entire tank except for the fittings, from what I can gather the engine cover also covers that top back 6-8 inches of the tank so when removed it allows access for those fittings. I dont want to permanently cover the fittings as I would like some type of access.
Excuse the pictures, I cant get on photo bucket here at work. The first shows what I think is evidence that the back top section of the tank was not covered by discoloration and the second pic shows the front part of the engine cover raised a bit for what I thought was access to those fittings. This 2nd picture is of another boat but I have those exact pieces stored under my deck.
So recap... I will mount with hardware on the two brackets front and back, I will foam it in as well. It will all be enclosed except for the front top area with the fittings.I will make sure bildge water can still run under the tank. sound ok? Hope that makes sense, harder to explain without more pictures. Thanks