Is RVer stuck with sticky black water valve?


By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is a letter he received from a reader while he was serving as’s technical editor.

Dear Chris,
Pulling the black water handle on my 2012 Entegra is getting more difficult compared to the gray water side. Is there any way to ease this or prevent it from getting even more difficult? —Ed

Dear Ed,
This is a common issue that black valves have over time and with repeated use. Lubrication wears off and material can get trapped in the track for the knife valve.

The best way to fix this for the long haul is to service the valve. The valve manufacturers like Valterra make seal replacement kits that are inexpensive and pretty easy to change. Once the tank is emptied, rinsed, and has been left open for 24 hours to “dry” out, you can go ahead and begin the job.

All you will need is a wrench, the kit, and a good valve grease. Dow-Corning 111 is recommended. Remove the four bolts from the valve head, and while lightly prying the pipes apart, remove the valve from the two flanges. There will be a rubber seal on each of the flanges. Remove those, taking note of how they seat in the flange.

Thoroughly clean the valve using a brush, cleaner (like Spray Nine) and copious amounts of water. Look for any damage on the valve that might indicate it needs replacement. Once dry, apply the Dow-Corning 111 to the blade of the valve on both sides and operate the valve until it moves smoothly. Install the new seals that come in the kit onto the flange and coat them with the Dow-Corning 111 to help hold the seals onto the flange, then while prying the pipes apart slide in the valve and align the bolt holes and install the new bolts that come with the kit.

While there are other “homebrew” ways of treating sticky valves that may work for a little while, the repair I noted here will make the valve operate like new for a long time.

As a side note, you may not “need” to replace the seals; however, any kink in the seal can result in a leak. For the minimal cost, I think it’s better to go ahead and change the seals. You can also replace the entire valve for a bit more money, but I would still apply the Dow-Corning 111 to the new valve before installing it.



5 Thoughts to “Is RVer stuck with sticky black water valve?”

  1. Seann

    Once you have gone through the work of disassembling it to clean it and use the rebuild kit would it not be easier and more practical to just replace the valve?

  2. Harry Salit

    In my coach it takes TWO hands to pull the pipes apart , where do I get the third hand to remove the valve?
    Even more difficult to replace the valve & pull the pipes apart. Pretty hard for another person to help when you are almost inside the bay blocking their access.
    So what is your solution?

    1. Dennis

      Harry, Try cutting two pieces of thin plastic sheet (like the sides of a plastic milk jug). Use these to act as a slide while pushing the valve in place. Once in place, Paul the plastic out and install the bolts.

  3. george

    I’ve never had an issue with a stuck valve but an issue with increased friction in the cable, usually at the handle end. Pull the handle out, spray lots of WD-40 on the exposed cable, run it back in and out several times and it’s good for several months.

  4. Jim

    After you dump the black tank pour a quart of vegetable oil into the toilet. Then operate the valve several times as the oil drains. I have found this works great and it is soooo simple and cheap. The same thing for the gray tank. I put the vegetable oil in my shower drain of an empty gray tank. Operate the valve a couple times as the oil drains.

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