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Old 05-10-2015, 08:12 AM   #1
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1972 31' Sovereign
Silverton , Oregon
Join Date: Aug 2014
Posts: 53
Black Tank Cracked - 1972 sovereign

I have a minor emergency, we have a trip scheduled for the 6th-8th of June, so I figured it was time to tackle the black tank leak. It turns out it wasn't the valve, it was the tank itself. Well the tank and the valve. so I need a new tank, I could try and weld it up, but the crack is in the area of the valve flange and is pretty long, so I would prefer to replace the tank. My problem is our mid bath late 1972 31' sovereign has the black tank on top of the floor. It looks like Inca has a H201 in the airstream specific catalog, that looks like it matches, other than the drain fitting should be 3" pipe thread.
There were no shims under my tank. but the Inca tank shows a slope. would you shim it, maybe some foam? I'll call them on Monday, but have any of you used this tank?
This is a double post, sorry

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Old 05-10-2015, 09:07 AM   #2
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1964 22' Safari
modesto , California
Join Date: Jul 2010
Posts: 499
Can Of Beans,

Sorry to here of your tank trouble. I do not have your particular tank, however I have used Inca Plastics in Ontario, CA. for all 3 of my tanks. I think they will also custom build almost any size or shape tank you need.

They are a great company, I can highly recommend them. I visited them and watched the process, Pretty facilitating for us nerds. I liked the way they spin on the fittings.
Hope you get fixed up in a hurry.


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Old 05-10-2015, 09:54 AM   #3
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1991 34' Excella
Princeton , New Jersey
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Considering your time frame I would consider fiber-glassing the leak area. I would rough up the area with #80 sand paper.

Place a layer of glass over the crack, leave it 24 hours, then drive sheet metal screws along each side of the crack, not driving them all the way in and then glass over again. Floating the screws will allow the second coat of resin to encapsulate them. Most resins can be over coated without sanding if the second coat is applied while the first coat is Green, not fully set.

If the valve connection is involved I would glass all the way around it for mechanical support for that side of the crack.

I have glassed the top of a tank that had a ft long crack.
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles

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Old 05-10-2015, 11:01 AM   #4
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2005 39' Land Yacht 390 XL 396
Common Sense , Texas
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If the tank is black plastic, which I suspect it is, then it is ABS. In such case, I would repair it with ABS glue and layers of glass cloth and/or plastic screen wire. An ABS tank repaired like this would be as good as new, IMHO.

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Old 05-10-2015, 09:31 PM   #5
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1972 31' Sovereign
Silverton , Oregon
Join Date: Aug 2014
Posts: 53
It's not abs, it's white polyethylene. Definitely a milk jug. it's only black on the inside . I could probably weld the tank, but I have doubts of the duration of the fix, and since I had to cut up the plumbing to get it out, I don't want to do it again any time soon.

It looks like the Inca tank isn't quite right per their print online, it would put the vent pipe in the bed instead of inside the bathroom. I'm hoping it's a misprint, or they can modify the shape to fit my application.
Thanks for all your replies, I'm glad to hear that you think highly of them, I'll definitely call them tomorrow.
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Old 05-11-2015, 08:38 AM   #6
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1973 21' Globetrotter
Houston , Texas
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I just recently bought an Airstream "stock" tank from Inca for my '73. During the order process, it sounded like they could spin on the fittings/connections wherever you wanted them, I just lucked out and the one they had was exactly configured as I needed it. I believe it took 2-3 weeks from the time I ordered the tank for it to arrive. Getting hold of someone there to talk to and to take my order seemed a bit of a game of phone tag, but they came through in the end. No complaints.

My old tank was polyethylene as well, and cracked particularly around the entry and exit fittings. My original tank had a slight slope to the bottom of it like the new one, but I don't believe there were any shims to support the slope, and the weight of the user of the toilet was all on the tank, which is probably what led to the cracking. When I rebuild my bathroom, I will enclose the tank in cabinetry that will support the user so that the tank isn't getting deformed, also plan to shim the sloping bottom so that it doesn't wobble around.

good luck!
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Old 05-11-2015, 08:46 AM   #7
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1955 22' Flying Cloud
1964 17' Bambi II
Clear Lake Shores , Texas
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Tank Support

Definitely bad practice to have weight on the tank top.
I had a nice aluminum box built to cover mine and support the toilet...
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Old 05-11-2015, 07:19 PM   #8
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1972 31' Sovereign
Silverton , Oregon
Join Date: Aug 2014
Posts: 53
The Inca tank was the right tank, the catalog dimension was just wrong. I ordered it today, under $300 shipped, makes me happy enough. hopefully I can get it inside of two weeks. I see what you mean about the toilet, it has the plywood to spread the load to the edges of the tank on the 3 sides, and it all seemed ok, no cracks on top, so I may just run with it for now.
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Old 05-16-2015, 09:17 PM   #9
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1972 31' Sovereign
Silverton , Oregon
Join Date: Aug 2014
Posts: 53
tank cracks

So after looking at the tank some more, the top is indeed cracked in several spots around the closet flange, so today's project was to build a support for the toilet, and my wife decided, a new tank deserves a new toilet, so a Dometic 311 will be going in as well.
looking at the old toilet support, I don't really understand what Airstream was thinking. the plywood support didnt reach the edges of the tank, and the tank is shorter than the box it's in.
the tank must have been hanging from the closet flange which was supported by 1/4" fiberboard until that sagged down and then it rested on the tank which sagged down.
so the new support is a 3 3 sided box of mohogany and 3/4" plywood that fits tight underneath the toilet support box. now the toilet will be supported by the floor. the tank will rest on the floor, and the closet flange hopefully will be screwed in only until it contacts the plywood support.

this all hinges on the new tank being similar to the old tank. I'm waiting till the new tank comes in to drill the hole in it.

anyway pictures
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Old 02-20-2016, 09:09 AM   #10
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1972 31' Sovereign
Silverton , Oregon
Join Date: Aug 2014
Posts: 53
it worked out great, Inca plastics was very helpful, he went out and measured the mold for me to make sure it would fit. The only problem is the vent pipe location, it still fits inside the cover in the bathroom, but \i had to clearance the floor a bit more. they moved the fitting closer to the toilet in order to get it firmly attached. the original airstream tank had the fitting right at the edge of the tank. it was only a difference of 1/2" or so.

my next project is to put in a gray tank after gutting out the interior.

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