Monday, September 26, 2022


Ask Dave: My RV’s hidden black tank valve is stuck open. How do I find it?

Dear Dave,
How can I reach my RV’s hidden black tank valve? It’s out of view. The valve is stuck open and I need to lubricate it, clean it or replace it. 2018 Winnebago Vista 31BE (Class A 32′). I have the Winnebago diagrams, so I know where it is—I just don’t know how to get to it. Thanks! —Tony

Dear Tony,
Winnebago has great resources on its website under Owner Resources. You can get wiring diagrams, plumbing schematics, and even 3D views. The list shows two sets of documents for your rig depending on the serial number. However, I could not see a difference in the location of the drain valve, so I think this is right.

In this first drawing, you can see the toilet, which is 89, and the “hidden” black water tank underneath that. Follow the drain pipe coming out of the side and you see an inline valve. When you hover over the valve, it is number 58. Pulling up the parts catalog it shows the valve remote.

Finding the hidden black tank valve

It does not show where the actual handle is. However, the red handle shown in the graphic doesn’t actually go to any of the valves, so it might loop to the inline one. Either way, it looks like you need to access it from inside a storage compartment.

From what I can see from the service compartment photo, the black waste pull handle is in the lower right. You can see the cable go into the compartment.

From the diagrams, we know the valve is to the right of the service center and piping. Looking at the compartment to the right, I see a couple of access panels. I would start by taking the smaller one off first to see what is behind. You might be able to get to it from the other side. If not, you will need to take the larger one off.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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Dale Terry
2 months ago

I have an attachment to screw into the city water connection to blow the water out of the lines with air pressure. When my black water flush system quit, I attached it to the flush connection and gave it one quick shot of air through the flush valve. The flush system began working again.

4 months ago

Agree what a nutty design why make it so hard to replace or repair something simple

4 months ago

What a messed up arrangement that is. Worse than some fifth wheels. Not a typical Winnebago design. I hope the owner likes the floorplan because from my view that rig sucks.

Tommy Molnar
4 months ago

Don’t you wish all mfg’s had a site like this!

Bob p
2 months ago
Reply to  Tommy Molnar

Most can’t even run wiring through their units with any commonality much less plumbing. I had a Bounder that I needed to find the wire from the solenoid for charging the house batteries while driving, a phone call to customer service for a wiring diagram (not a schematic) got the answer, there’s not any wiring diagram as there are 6 teams wiring these units and each one has their own way of wiring, but it is wired as per the schematic. Ha! Instead I ran a new wire underneath protecting the wire. I’ll Never buy that brand again. Live and learn!

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