RV Gray Valve Repair — REAL-TIME DIY Holding Tank Valve Replacement

TheRVgeeks Plumbing, Repair, Water & Sewer 37 Comments

The blade valves on your black and gray tank outlets are the only things standing between you and a tsunami of… well, you get the picture. It’s impressive how well they work… and how long they can last. Our gray valve is the original one that came installed on our RV when we bought it back in 2003. So it’s pretty amazing that it’s held up to full-time use all these years, quietly doing its job of controlling the gray tank contents, letting it out only when WE want it to, and keeping 100% of the 65-gallon-capacity tank fully contained the rest of the time, even while vibrating along thousands of miles of roads.

But recently we began to notice a couple of symptoms of a failing valve: (1) An occasional small drip from the handle itself (primarily when pulling it for dumping) and (2) A small amount of water accumulating behind the sewer pipe cap, even though both blade valves were closed. Thankfully, it was the gray valve that was failing, and not the black valve (hang in there fella)!

So we’re doing a replacement… and we’re doing it “real-time” with only the slightest bit of editing, so you can get a feel for how long a job like this takes, and how easy it is to do.

This is our second “Real-Time DIY” (after our recent propane detector replacement). Leave a comment below to let us know if you like this type of video and if you think we should try doing more of them. And be sure to share any advice you you might have from any experience you’ve had replacing your black or gray valves. Maybe we got lucky and ours was just particularly easy!


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We're handy RVers, not professional technicians. We're happy with the techniques and products we use, but be sure to confirm that all methods and materials you use are compatible with your equipment and abilities. Regardless of what we recommend, consult a professional if you're unsure about working on your RV. Any task you perform or product you purchase based on any information we provide is strictly at your own risk.

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Comments 37

  1. I have a question. Does the new valve have an obvious orientation, or can it go either way? Never replaced the valve, but just bought a 22 year old NASH and need to replace valves.

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      Hi Shari. Good question! Ours did not appear to have any orientation… and the installation instructions didn’t indicate that there was any special way it had to go in!

  2. Thanks for the video. It’s always good to see how someone else did it prior to tackling a task yourself.
    One suggestion I would add is to have a small catch pan of some sort under the pipe when removing the old valve. That way if you have a leak it won’t get on the floor of the bay. I also would recommend a little plumber’s grease on the seals and valve prior to install.

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  3. You two probably already know this but for those who don’t…….. Before working on the black / gray valves dump the tanks with the wet bay side of the RV slightly lowered to get all of the contents out then raise that side of the RV to slightly higher than normal to stop anything dripping out when you take the valve (s) off.

    Richard.

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  4. One more thing….about greases: I use plumber’s grease for seals that are constantly exposed to water- including a Valterra knife valve I use on a Flush King. It was greased over 2 years ago and I haven’t needed to reapply since then. The stuff is from ACE Hardware but I’ll bet any brand is fine…Very cheap- I think 2 or 3 dollars for a tube.

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  5. Excellent, guys. But one question: are ALL grey valves 1 – 1/2 inch valves? I’ve been assuming mine (hidden behind the wet bay facade) is probably a 3″ like it’s black water twin.

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      Hi Don! We do know that at least one manufacturer uses 3″ pipes and blade valves on their gray tanks, as opposed to just on the black tank: Entegra, formerly Travel Supreme.

      1. Thanks guys. I’m pretty sure my Country Coach uses 3″ valves on both tanks. But I guess i’ll have to verify that before buying a replacement. My grey valve leaks slightly (from the flange) when it’s open, but not when shut.

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          1. The trials of having bought an old Country Coach! The wet bay wall is a sheet of stainless, and all the key bits are hidden behind that pretty facade. Which I’ll have to remove to get to the valves. I’ll figure it out, but it isn’t going to be obvious until I get in there…

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            Uggghh… sorry to hear that, Don! We sure wish RV manufacturers would take some time to consider what’s required to access some of these places for repair/maintenance! It’s easy for THEM to put stuff together when the RV isn’t complete yet, but SHEESH can it be a PITA doing it after the fact! Good luck!

  6. I carry a T58 screw on waste valve that connects to the waste pipe the same way a sewer hose connects. I used it once when I was not thinking when cleaning in the bath and disposed of a half sheet of paper towel into the toilet which then didn’t allow my black tank valve to fully seat. I originally purchased the valve as a temporary fix if one of my valves began leaking. I disconnected the black water valve and pulled out a fragment of paper towel and that fixed my leak. And as always, I enjoy every video you produce.

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    2. Interesting. I also have a “screw on” valve on the end of my waste pipe – but it’s always there. I use it as a “master valve” to ensure that any slight leakage isn’t waiting behind the cap when I unscrew it. But it has another even better use, which was recommended by Country Coach in our Owners manual: When dumping, I attach the hose and open the master valve before opening black water. Once Black has been emptied leave the black valve open, close the master and open the Grey water valve. Grey water will then back-fill the black tank. I let maybe 1/3 of the grey tank into the black, then close grey and open the master again – dumping the grey water which has rinsed out the black tank. Once that’s gone, I close black and open grey to let the remaining grey water flush out the hose. This system keeps the black tank much cleaner than the fresh-water flush fitting, and is super easy to do. Think about it… :-)

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        1. I also use the T58 when boondocking an extended length of time and my grey tank is getting near full so with the T58 installed and closed I open my grey valve to flood the pipes, and then open my black valve to flood grey into my black tank.

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  7. Fantastic, a real help. The valves do last a long time but, sooner or later will require replacement. Those of us that have to deal with these Items appreciate your expert help and yes, saving those bolts is a very good idea. Always find your videos helpful.

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  8. Another great one Peter. I know my day is coming, are coach will be 20 next year, and the valves are still hanging in there. This was helpful, I didn’t know how they were changed out. I could imagine having to cut pipes and all kinds of issues, so this was definitely helpful.

    Good grief, get yourself some ratchet wrenches! The ones with the flexible head are particularly useful.

    The nuts and bolts don’t care which direction they were put in, so if you did have to put a bolt on the plate side, no big thing.

    I’m a big fan of stainless steel lock nuts. Don’t rust and the road can’t vibrate them loose. Just a little extra peace of mind, although you would have to buy them, and flat washers. Ok, I live in NE Ohio- the rust belt, so for all you that go gallivanting around South east U.S., you don’t have that problem and could use regular ones.

    Don mentioned silicone grease, it would help hold the seals in place while you were assembling. So would vaseline, but you may not want a petroleum product on the seals. Nobody wants to do that twice!

    Thanks again, it’s nice to see how it’s done, and make sense of why I’ve seen them called blade valves. You know, that oh moment! 😀

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  9. Hi Guys,

    I’ve replaced lots of these (mostly for my kids and rv’ing buddies). In watching the video I saw that neat soap dispenser..an old time one, mounted there on your manifold plate. Can you source that one for me? I’ve looked high and low trying to find one. They used to be in all the public and school restrooms everywhere.

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      Great question, Don! We didn’t use any type of lubricant because the instructions didn’t call for it, the valve worked smoothly right out of the package (possibly pre-lubricated?) and the old one never got lubricated in all those years, so we figure it’s probably okay!

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