under belly sag

[locogk28]

we just purchased a 2018 keystone hide out 299rlds. where the black tank is the under belly is sagging what is causing this and could my tank me broken at mounting points ?

[cliff]

There are a couple of causes. i had one where the valve leaked and sagged the chloroplast. That's probably the easiest to fix. Another is the black tank or its vent is leaking. Then, maybe the bolts. You got to open the under belly to see. It ain't no fun. I used a piece of sheet aluminum when I was done and sealed the edges with acid cure slicone.

[JRTJH]

Before you go "opening the underbelly looking for problems that don't exist" you might want to do some comparisons to other trailers....

Coroplast will "droop in the middle" on "perfectly normal trailers", so without knowing what you're describing and whether it's a slight bow in the middle or a "nearly dragging the ground and obviously filled with water or XXX"

Don't jump on the bandwagon of "It's a problem and I'm screwed" until you compare it to other trailers. My coroplast has "sagged in the middle" since the trailer was new and it's no worse than it was when we took delivery in 2013.....

[sourdough]

John is right. If you have some "drooping", until you see something that indicates there is a cause I wouldn't go tearing up everything to find there was no reason to do it. Mine droops and has for years. When it did spring a leak from the galley holding tank it conveniently leaked right through a screw hole and alerted me.:D

[bsmith0404]

Mine also has a sag. A lot of it is caused by the insulation in the belly. The colorplast will compress the insulation near the edges where it’s screwed to the frame, but as you get further away from the screws, the coorplast saga instead of compressing the insulation. You can always use a small drill bit to place a small hole in the center of the sag and see if anything comes out.

[Macgregor]

Be careful if you are going to do any drilling or trying to put a screw in to support the sag. The tanks may be right against the coroplast. There are no supports for the coroplast in the tank areas on my trailer and it does sag a bit.

[Badbart56]

Make sure there is no liquid causing it to sag. I overfilled one of my grey tanks because the gauge didn't work and it over flowed from the vent. The RV technician simply drilled a hole in the middle allowing it to drain. I keep better track of how many showers between draining the tank now!

[bsmith0404]

Make sure there is no liquid causing it to sag. I overfilled one of my grey tanks because the gauge didn't work and it over flowed from the vent. The RV technician simply drilled a hole in the middle allowing it to drain. I keep better track of how many showers between draining the tank now!

I leave the gray shower valve open because that tank fills too fast. I’ll dump the galley gray after the black to help flush “stuff” out of the hose.

[mtofell]

Make sure there is no liquid causing it to sag.

I agree with this - you should be able to feel if its holding water which would rule out a few possibilities.

[flybouy]

I started to get "underbelly sag" when I hit my late 50's.:facepalm: Oh, you're talking about the trailer, never mind!:lol:

[flrtrader]

I've heard there are kind of easy replacement material for this underbelly fabric. Has anyone installed that kind of "Hard" replacement?

Thanks

[Jerry Bies]

I agree with badbart56, drill a 1/4 or 3/8 hole in the middle of sag,see what comes out. Have you lost any hydraulic oil, one of my hyd lines was 1/4 turn loose that found its way into the sag. I cut the underneath cover big enough to fit my head in to find the drip. I cut access hole on 3 sides and used aluminum duct tape to seal covering.
Used black spray paint to cover up aluminum tape. Ok now

[KRumm]

If it bothers you you could do a couple things... open it up and in the middle install a piece of wood strut that you can put a screw in the middle, or drop a 2x4 piece from the floor in the middle to the height of the belly giving you a screw spot in the middle or without opening up the belly add an aluminum strut across the sag area and secure it on each side...

https://www.lowes.com/pd/Steelworks-1-2-in-W-x-8-ft-L-Mill-Finished-Aluminum-Weldable-Trim-Channel/3058183

[chunker]

First I would get under the trailer and push up on the coroplast. It naturally sags between the mounting points. Normally it will push up with little resistance. If it's hard against something, like an unlikely tank sagging, there will be considerable resistance to pushing up. Randomly drilling a hole in the coroplast could result in a face full of what ever liquid has collected there and potential drilling into a tank with even more catastrophic results. IF you feel resistance when pushing gently up on the coroplast, remove some side screws and bracket to view it from the side. You've received a package or bought a produce with a warning label, "DO NOT CUT". That warning is for a reason and should apply to areas around the tanks. Look before you leap/cut/drill.