Grey Tank 2 only dumps to gray tank 1

2021 Heartland Road Warrior 351. Four months old. Bath and half. Both front and rear dumps have worked perfectly until this weekend. Grey 2 showed 1/3 full and wouldn't dump. Black 2 dumps perfect. Front tanks dump perfect. I added extra valves to both front and rear to avoid the surprises we all seem to have experienced when pulling caps to install hoses. With my front main dump open, my Grey 2 is now dumping out my front dump. There has to be an auxiliary line in place for this right? I'm thinking some kind of blockage below the grey valve but above the Tee on the rear dump. We are leaving wednesday for a 10 day trip and I hate to head out not knowing the issue. Local dealer has been less than helpful.


Active Member
You could put some dye in each of the tanks and watch as the water comes out to be sure you know which tank the water is coming from as you pull the valve.

Additionally, you could drop the underbelly to take a look and see how things are plumbed. You could also cut the underbelly to look up inside, and then tape it back together, but unless you have a really good idea of where you want to look, it may just be easier to drop it. I have used both options depending on the problem.

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Well-known member
Don't trust those level gauges. Your tank could be empty. I'd open the drain just a little if nothing comes out, then add some water to the tank & see it flows out. If it doesn't then you have a blockage. Good luck