Black tank flush clog

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2humans_2bulldogs

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Nov 28, 2016
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I am currently dealing with a clogged blank tank flush and it is pretty frustrating. I have a 2015 Keystone Cougar 337fls 5th wheel. It has a tank flush that you hook the hose to from the outside.

I have tried filling the tank with "Unique" waste digester. I have also been using Tank tech RX for a couple of months now and letting the tank get nice and full before letting some water out, per the instructions. I really don't want to have to pay to get this unclogged and was wondering if anyone here has ever dealt with/solved this issue???

Any suggestions are greatly appreciated!!!

Thanks!
 
I don't know how the plumbing is set up in that unit, but there are wands you can get that hook to a garden hose to blast apart the clog. I made one years and years ago out of 1/4" copper tubing. It could be bent to hit the sides or bottom of the tank as needed. You need a pretty straight shot from the commode into the black tank for that one to work though...
Good luck.
 
You've been a member for 2 years now so I assume you've always let the tank get nearly full before you dump and that you don't keep the drain valve open while camping. So it appears like Caryl asked, is it your flusher that's plugged? I had one a few years ago that plugged up.  The campground I was staying at had a water main break and after fixing the break, my flusher picked up some sand from the water system and plugged up. The only way to fix it was to cut a hole in the belly and remove it from the tank. Then flush it out real good and reinstall it.
 
yeah, I guess I misread the OP. It's NOT the tank drain valve that's plugged but the flush system to rinse the tank?

Maybe this will help: 
https://www.youtube.com/watch?v=-YPkEcyhf3k

 
Two things to try. Hook an air compressor up to the fitting and slowly raise the pressure until the clog breaks free or you get nervous about the pressure level you are reaching. Or with the tank empty, use a shop vac to try to pull out the clog if you think something may be clogging it up from the inlet side
 
kdbgoat said:
Two things to try. Hook an air compressor up to the fitting and slowly raise the pressure until the clog breaks free or you get nervous about the pressure level you are reaching. Or with the tank empty, use a shop vac to try to pull out the clog if you think something may be clogging it up from the inlet side
Click to expand...

We need to know what is plugged. We are just speculating right now.

If it is the flusher that's plugged and you decide to use a compressor, something you must know. In my case, I had a tank rupture. That's another story. I contacted the manufacturer and they said they only test their tanks to 1 PSI.  So if you go above 1 PSI, you could be in for a BIG surprise. Your tank may take 15 PSI but I wouldn't take a chance. Make sure the drain is open and the sewer discharge pipe has no cap on it.

 
Rene T said:
We need to know what is plugged. We are just speculating right now.

If it is the flusher that's plugged and you decide to use a compressor, something you must know. In my case, I had a tank rupture. That's another story. I contacted the manufacturer and they said they only test their tanks to 1 PSI.  So if you go above 1 PSI, you could be in for a BIG surprise. Your tank may take 15 PSI but I wouldn't take a chance. Make sure the drain is open and the sewer discharge pipe has no cap on it.
Click to expand...

Perhaps I'm missing something here, but isn't the tank vented to the atmosphere through the sewer vent stack?  I can't imagine how you could pressurize the tank unless you cap that pipe.  Seems to me that blowing out the flusher should be unable to pressurize the tank assuming the vent isn't blocked.  I'd be more concerned about blowing up the water line to the flusher, blowing it off the flusher altogether or blowing the flusher into the tank.

Naturally, fresh water tank is another story.
 
Perhaps I'm missing something here, but isn't the tank vented to the atmosphere through the sewer vent stack?  I can't imagine how you could pressurize the tank unless you cap that pipe.  Seems to me that blowing out the flusher should be unable to pressurize the tank assuming the vent isn't blocked.  I'd be more concerned about blowing up the water line to the flusher, blowing it off the flusher altogether or blowing the flusher into the tank.
Click to expand...
Me too. Yes, the tank is vented and it is highly unlikely a vent could be clogged tight enough to build much air pressure in the tank, if any at all.  The flush water line, however, is an entirely different matter. A kink in the water line or tiny clog at the jet into the tank can block it completely and it will pressurize in an instant.  Also be aware there is a anti-siphon valve (backflow preventer) in that line that could be damaged.
 
The first lines the OP posted:

2humans_2bulldogs said:
I am currently dealing with a clogged blank tank flush and it is pretty frustrating. I have a 2015 Keystone Cougar 337fls 5th wheel. It has a tank flush that you hook the hose to from the outside. ?
Click to expand...

Pretty clear to me that the problem is in the flush, not the tank clogged.
 
kdbgoat said:
The first lines the OP posted:

Pretty clear to me that the problem is in the flush, not the tank clogged.
Click to expand...

If it is the flusher, the only way to clear it is by taking it apart. Blowing air into it would only make matters worst. They probably picked up some sand from a water system and the sand plugged up the small holes. Once it's removed, they'll need to clean out the holes with a small pin.  Been there done that. 
 
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