Black Water Flush Blocked

[ElliotA]

I just picked up a 2006 28' Safari that had basically never been used. The owner lived in it for three months while she built a house and after that it had been sitting in a field for over 4 year.

When I first took it out I found that the black water tank discharge was clogged with toilet paper and I used a flush adapter on my sewer hose and a hose wand to wash it all loose. I assume she never used chemicals and used regular toilet paper.

Everything seems to work right now except that there is a blockage in the built in black water flush system. When I connect a hose to it no water goes into the black water tank and all I get is an overflow around the skid plate protecting the black water tank. I checked inside the bathroom where you can see the plumbing for this system and there are no leaks there.

Is there a valve or something that needs to be opened? Remember this trailer has almost never been used and for sure the black water flush had never been used.

Elliot

[dznf0g]

I sounds to me like there is a leak where the BW flush line enters the black tank. If that's the case, it will involve some disassembly to get to it. I am not sure of your unit's setup, but on mine, I believe I would have to drop the tank pan and tank. Or, at least CUT an access into the pan.

I would tell you to just forget using the flush system, (many seem to think it is ineffectual at best anyway) except if you do have a leak there, I believe you will leak black water into the pan whenever the level is as high as the flush head. That could be NASTY!

[Silver Goose]

Look for this valve. I found this under the closet on my 27FB. It may be elsewhere in different floorplans. It could be anywhere in the line between your BW flush connector and the tank sprayer and should be in some accessible location (under sink?). Mine was secured too tightly to the wall from the factory and was cracked allowing water to run out under the belly when I tried to use it.

If you can get a visual on the valve, have your helper turn on the water. The water pressure moves the piston to the upper position, applying pressure to the ball/spring valve and then passing on to the sprayer. The ball valve is supposed to prevent back flow and when pressure is removed, the piston drops to the lower position allowing the input line to self drain.

By observing this valve, you should be able to determine if it or its connections are the problem or if the leak is beyond at the much less accessible sprayer head.

[dznf0g]

Originally Posted by YankeeDoodle

Look for this valve. I found this under the closet on my 27FB. It may be elsewhere in different floorplans. It could be anywhere in the line between your BW flush connector and the tank sprayer and should be in some accessible location (under sink?). Mine was secured too tightly to the wall from the factory and was cracked allowing water to run out under the belly when I tried to use it.

If you can get a visual on the valve, have your helper turn on the water. The water pressure moves the piston to the upper position, applying pressure to the ball/spring valve and then passing on to the sprayer. The ball valve is supposed to prevent back flow and when pressure is removed, the piston drops to the lower position allowing the input line to self drain.

By observing this valve, you should be able to determine if it or its connections are the problem or if the leak is beyond at the much less accessible sprayer head.

Although the layout may vary between floorplans, my airbreak also leaked, but it showed as dripping at the joint between the belly pan and the rolled gray sheet (at the frame) as well as through the city water access compartment, outboard and rearward of the tank pan. I had no dripping at the pan

[ElliotA]

I checked the airbreak valve as suggested and it seems to work OK and is not leaking. I guess there is a breakage where the line enters the tank.

Is this something that could have happened due to freezing weather? I had to replace the Thetford toilet valve as it was cracked and leaking due to not being drained and freezing.

[dznf0g]

Probably not, unless the black tank was significantly full during the freeze. I suspect just a bad fitting of the spray head into the tank.

[KJRitchie]

When I winterized last December I was at a campground with full hook ups. It was about 32F. I was able to fill the black tank up to almost full, dumped, the tried to fill up the black tank again via the flush. No water was coming into the tank. My black tank flush line has no one way valve. It was broken and replaced it back in 2013 with an elbow fitting. I figured it was just cold or maybe frozen so I didn't worry about it. I just dewinterized, the temperatures in the 70s and the black tank flush line is still plugged. There is no screen on the black tank hose fitting so maybe their is grit in the line. I'm wondering if hard water can plug the small holes. I may try putting a water softener in the tank and also pumping is some CLR to the valve to see if I can clear it. If that doesn't work looks like I'm going to have to get the valve replaced.

Kelvin

[gnowlin]

just wondering if you ever got a resolution to your backflush line being plugged.
just had the trailer out this week-end at Abilene state park, first time since being winterized in oct. last yr. backflush worked fine then. tried to BF today, and water would not enter tank. I have not checked for the back flow (preventer) valve that is supposed to be inside somewhere. just finding about that. any suggestions are greatly appreciated.

silver bullet,& little blackie: 2012 , 25' International,/ 2015 , 2500 chevy truck.

[Al and Missy]

Mine was plugged with stuff from the tank. The holes are small and when the level of the black tank gets high enough suspended solids can be forced into the holes. when the level goes down, the stuff dries and hardens.


On my trailer the fitting was mounted in a hole in the side of the black tank with three screws and bedded with a sealant. When I had to replace my valves I pulled it and cleaned it by soaking it in bleach overnight. It still doesn't work so I'm guessing the line is blocked somewhere, probably plugged up with the same stuff that clogged the fitting. Also there is a check valve screwed onto the fitting in the water compartment but I can't get it off to check it.


Al

[cwf]

these are 'standard'... buy a new one and replace the old.. It is the American way!