Black tank draining problem.

[CM Sandman]

Hey Texas Camper,
My Girlfriend and I are full-timers, & have a "New" 2017 Solitude 375 RS that we just traded up for it at the end of 2017 & LOVE IT. However we have the same type of "problem". We had originally purchased a 2016 Heartland Edge 397 Toy Hauler in May 2016. (Lots of stories about it not many good...) When I pulled the dump valve on the EDGE there was always a massive rush of brown waste water filling the pipe completely and it would eventually slow to a trickle. On the new Grand Design when the tank shows 3 or 4 lights and I pull the dump valve for my black tank I can usually hear a glug glug glug sound like there is a vent problem and it's sucking air from somewhere or something? The waste water comes out just like you said in a somewhat slow flow only filling the sewer pipe about 1/2 way. After noticing this the first couple of dumps I did a bit of research and investigation. I read on a couple of threads that some grand designs had been sold with vent pipes or toilet pipes installed incorrectly, (Too long, sticking down into the tank) so I pulled the vent pipe (after checking with GD) out of my black tank and checked that it was installed correctly and put a sewer camera in to check the toilet pipe too and they both look to be installed correctly. So then I went up on the roof and ran an small hand-crank sewer auger down the single vent stack and it went right down and I could hear it splashing and when I pulled it back up & out, it had evidence of TP on it so I'm pretty sure it went into the black tank. I also installed a new Camco Cyclone Sewer Plumbing Vent. The new vent did not seem to make much difference with my case but i do know they help pull the sewer gases up and out better than the stock ones. So all that said and done I've just been trying to dump it every week on Sunday. On Sunday it's usually at 3 lights so I hook up the flusher hose and let it run for a minute or so and then pull the the dump valve, the waste water comes out slow but it comes out. I use TanktechsRx to treat the tank and they recommend that you do not completely empty your tank so you retain some of the "mother" culture. So the little bit left in the tank works out fine. I've also read in a couple of posts about some peeps having problems with the valves not shutting correctly and I think this has happened to me a couple of times too. What I mean is the valve was pushed in all the way but was still letting liquid seep past so when I went to dump there was not much liquid in the tank and the waste did not flow well, in fact the second time it happened I pulled the dump valve and nothing came out! So I disconnected the flusher hose and connected it to the Camco RhinoFLEX Rhino Blaster Back flusher I keep on the outlet pipe and closed the gate and turned it on. Almost immediately the waste started flowing but it was really thick like the water had seeped out. So now when I close the valve for the black tank I keep an eye on the clear tube and make sure the water stops flowing before I clean up and put stuff away. Still at a loss for what the problem actually is but the grey tanks seem to flow much better when I dump them?

[Juliet Wiskey]

I just purchased a 2018 Grand design Solitude 373fb and I have the same drain problems. I pull any of the four dump valves and it takes 10 to 15 seconds for the fluid to start running. It runs real slow. I called the factory and asked a service rep for any documentation they would have on that particular model that would illustrate the layout. He did send me this

file:///var/mobile/Library/SMS/Attachments/b6/06/B90D72E1-3E24-4EC1-ACBF-18FC6A5CE49F/IMG_2927.jpeg
You will notice the two forward black and gray tanks face for and aft with the outlets facing rear. And the two rear tanks go side to side with the outlets to the right. That means the rear tanks dump out and to the left hits another elbow to the left into the main manifold. Each of the forward tanks enter this manifold as well makes one more left and out. That’s a long run and a long cable pull to the dump valves as well


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