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Old 02-03-2016, 07:18 AM   #1
1 Rivet Member
2011 27' FB Flying Cloud
Box Elder , South Dakota
Join Date: Nov 2013
Posts: 8
Thumbs up Black Tank Drain Valve Won't Close !

We have a 2010 27FB Flying Cloud. We are very careful about what is put into our toilet, so we make it a habit to use campground restrooms for our solid waste. When we must use the toilet for solid waste, we always use RV safe toilet paper. Recently, we found it necessary to do just that. When we did our dump, we could not make the drain valve completely close. This repair could be expensive, so we opted to fix it ourselves. Research revealed that we should use a good cleaner,(like Happy Camper Extreme Cleaner), or we could buy a high pressure wand, but most of the wands are too short to reach the valve through the toilet. Then we found what is called a "Flush King" ! This devise is used to back flush into the black tank from the outlet pipe. The reviews looked good, so we purchased the Flush King at Camping World for $50. (Yes, you can probably get it cheaper !) After doing several back flushes, the debris was flushed out of the tank and away from the drain valve. The Flush King is now part of our "Full Timer" inventory.

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Old 02-03-2016, 08:19 AM   #2
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2012 27' Flying Cloud
W , New England
Join Date: Oct 2012
Posts: 4,679
Black Tank Drain Valve Won't Close !

That's great! Panic inducing experience I'm sure!

I learned a trick here that helps too. First - before dumping the black tank, be sure it and the gray are 100% fill. Empty the black and the nearly 40 gallons of water will do a pretty good job moving everything out of the system, but here's the trick. Leaving the black handle out, lift up the stinky slinky so it's above the pipe then open the grey tank for say 5-8 seconds then close it. This will put 10 or so gallons up through the pipe and in to the black tank as a sort of back flush too. Drop the slinky and the black will drain again. I usually do that twice then close the black and let the gray finish.

Good luck!

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Old 02-03-2016, 09:18 AM   #3
1 Rivet Member
2011 27' FB Flying Cloud
Box Elder , South Dakota
Join Date: Nov 2013
Posts: 8
We tried the Stinky Slinky maneuver, but that didn't work.
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Old 02-03-2016, 09:59 AM   #4
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2005 30' Classic
Burlington , Ontario
Join Date: Sep 2008
Posts: 2,269
I put a third slide valve on our combined grey/black water outlet. (where the cap goes.)

The main reason I put it on was to eliminate the small amount of waste water that sometimes comes out when I am at a new campsite and remove the cap to hook up the slinky.

I think this happens sometimes due to sight differences in level from one campsite to the next and waste water remaining in the piping after the valves - or maybe slight leakage from the slide valves.

It did occur to me also that if could provide a handy temporary solution if at any time one of the main slide valves won't close properly - as you experienced.

Brian & Connie Mitchell

2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.
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Old 02-03-2016, 04:10 PM   #5
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1988 25' Excella
Montrose , Colorado
Join Date: Sep 2007
Posts: 28
Black water valve

I agree with all of the above methods to clear the black water tank. We have had our trailer for 29 years, original dump valves. Grey water valve is still nice an easy to open/close. Black water a little stiff but still works. Both with no leaks. I have recently given attention to the black water valve. First, I dumped about 5 gallons of very hot water into that tank after draining it. Let water sit for half hour or so, then open and let it drain for an hour or so. Turn of the water supply to the trailer and drain until no pressure or flow, to keep water out of the tank. Close the BW valve and dump in about a quart of vegetable oil, the least expensive that I could find. Let it sit for an hour, then go to the valve handle and then quickly open and close it. Do this about 6 times to work the oil into the valve grooves. Then from the outside, while the valve handle is pulled out, using silicone spray, spray the handle shaft as far as you can, back into the housing area and pull the handle in and out several times until you feel it becoming free with less resistance. Give it try. Sure worked for me.
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