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Old 01-10-2021, 02:35 PM   #1
New Camper
Join Date: Jan 2021
Location: NC
Posts: 1
Black tank sagging below basement

Hi all,

We purchased this used 2018 Sunset Trail 289QB travel trailer in August. Just returned from a trip from FL to NC and when i was winterizing it I noticed the black tank is now visibly showing underneath (didn't notice this in FL).

The tank was empty for traveling, I tried manually lifting it to see if it was loose and it wouldn't budge (good?), I put blocks and wood underneath the tank in case it dropped more (it didn't) and filled it for one last cleaning. There were no leaks in or outside of the camper, and it didn't sag as a result.

My question is, how can I fix this? I couldn't find any diagrams of the underneath without the (not sure what it's call, black cardboard like stuff).

I saw other threads where this happened to the freshwater tank and folks reinforced it with wood.

I'm assuming to cut the black 'cardboard' around the tank underneath and see what has come loose. and go from there?

Thanks all.
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Old 01-10-2021, 03:09 PM   #2
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What ever is on the bottom for a cover should be fastened to the frame with screws or the like. I would take those out to get it opened up for inspection. If you cut it, you will be making more work for yourself.
My guess is they have/had some type of support in there for the tank that let go allowing the tank to drop. It probably either broke or pulled loose the PVC pipes that are connected to the tank also.
Once you get it back up and fixed, put some extra support pieces under it. Probably the easiest would be either angle iron or lite channel iron running across frame to frame.
Good luck.
Let us know how it turns out.
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Old 01-10-2021, 05:51 PM   #3
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What I found to be a good support is a metal fence post. It's design prevents sags.

Cut cut the wings off and cut to length. Then bolt to frame.
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Old 01-12-2021, 04:21 PM   #4
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Yea that tank is definitely broken loose. I would be amazed if the pipes are still connected at the top. those fence posts are excellent for bracing tanks up.

You need to get that belly skin down and get that tank back up. I suspect the cross members pushed out and the lip of the tank slipped off and down.

I've seen metal pipe straps used to keep the crossmembers from spreading once tanks are back in place.
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Old 01-17-2021, 03:22 PM   #5
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Had that happen on my grey water tank,screws in one of the straps stripped out,went back with bolts
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Old 01-17-2021, 03:40 PM   #6
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Youíre definitely going to have to drop the coraplast underbelly. Itís not all that difficult- just a little time consuming. Iím sure there are plumbing lines on the verge of breaking. The good news is this gives you a chance to do a complete inspection of the stuff in the underbelly. Also a good opportunity to install tank heaters or add insulation if thatís something youíve been thinking about. Iíd also give a hard look at the mounting straps of your fresh water tank. They usually skimp on securing those and many have posted about their fresh water tanks breaking loose.
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Old 01-17-2021, 04:55 PM   #7
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Once dropping the underbelly watch for screws, scrap wood pieces, hunks of wire & who knows what else, the guys on the assembly line don't bend over to pick up anything, if it falls it stays.
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