Thursday, December 8, 2022


Is RVer stuck with sticky black water valve?


By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is a letter about a sticky black water valve 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.


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9 months ago

I have had good luck with this product.

9 months ago

I think the difficult ones are trailers- of all types. My MH is pretty much as described by Chris…it was very easy. Well, actually it was also very easy on my daughter’s TT as well! All the valves are just under the frame on the outside. A really easy fix for a sticky valve might be to simply lube the shaft- that worked for me.

9 months ago

A picture of a taken apart valve would have helped this article immensely.

9 months ago

Easy said, pry apart the 2 pipes and insert valve.
Easy if you have 3 hands, not with 2, seals fall out even with sticky stuff, when you are in a awkward position under the RV!

9 months ago
Reply to  Harry

What Harry said!

Bob Palin
9 months ago

All you will need is a wrench, the kit, and a good valve grease.”

What a joke, you also need to be a contortionist to get to the valve, I can’t even see mine buried in the tank area somewhere.

Joe Allen
9 months ago

When our valves start, emphasis on start to get sticky, I spray silicone in there after I dump and rinse. Works! You have to attack the valve when it starts to be a problem.

9 months ago

One “home brew” solution I really like is to drill into the valve body under the handle and add a zerk (grease nipple). Pump a bunch of grease into the body and work the valve back and forth and voila…

9 months ago
Reply to  Don

Remember that any petroleum based product will degrade rubber parts. I drilled a hole above the handle and squirt silicone into the blade area at least once a month while using the MH, there are instructions on how do it on you-tube however I installed a flat washer and then a rubber washer on the screw first. Along with the silicone spray I also leave the black tank valve open for a short period while the gray is opened, finish almost flushing the gray and then open the black again, the soap tends to lubricate the black tank seals.

David Ciummo
9 months ago
Reply to  Joe

Joe is right, I did the same thing and found some plug screws that I had laying around, or get a threaded set screw, and spray silicone into the drilled hole and works like a charm.