By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is a letter he received from a reader while he was serving as RVtravel.com’s technical editor.
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 the sticky black tank valve from getting even more difficult? —Ed
This is a common issue that black tank 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. 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. Molykote 111 from Dow Corning 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 Molykote 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 Molykote 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 tank 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 Molykote 111 to the new valve before installing it.