Blocked Built in Tank Spray System - Montana Owners Club

ontheroad10 · 08-02-2017, 10:44 AM

I am sure others have had this experience. For some time I have had problems trying to spray out my black water tank with the built in system. Water comes spewing out at me after trying to run water through it. Seems like nothing is getting inside. I have been told to try to apply chemicals to the tank in an effort to dislodge possible built up on the hose going into the tank. I know that another option includes removing the connector from the outside, but I have been discouraged from doing that by a technician. I have even read that people have been encouraged to run a compressor though the opening. Anybody successfully handled this problem?

Butch & Kathy · 08-02-2017, 10:53 AM

It sounds like your back flow device is bad. I had similar problems and also developed a leak. Like most people I removed and bypassed mine. On the 3160RL it is under the bathroom sink. You should locate yours and try bypassing.

fre1fred2 · 08-02-2017, 10:54 AM

How ironic...I tried mine for the first time this weekend and had all kind of water squirting out at the connection...I thought I just needed to add another rubber washer..but looks like it may be another issue..

cw3jason · 08-02-2017, 01:46 PM

Many post about the back flow preventer being installed backwards. it is a check valve and will only allow flow in one direction. could be under the bathroom sink or in a wall behind the shower or like mine in the basement behind the panel going to the convenience center. check for proper installation and function. it is easy to remove and is just a spring loaded check valve. I have also seen a few post about a kinked line at the black tank, just before the nozzle. Hope you find your issue.

ontheroad10 · 08-06-2017, 03:38 PM

Thanks to everyone that responded. I looked under my bathroom sink and found this setup. I was told that the white tubes connect to the anti siphon valve. Anyone recognize it. Hope my upload works

Bad Moon · 08-06-2017, 04:56 PM

Same problem with mine. I guess I need to start tearing into it.

twindman · 08-06-2017, 06:03 PM

Mine quit working and I looked under the sink. Just took the thing apart and all it had was a marble in a tube (sort of). I took the marble out and it works great. Of course no built in back flow preventer now.

jeff_banning · 08-06-2017, 06:14 PM

Quote:

Originally Posted by twindman

Mine quit working and I looked under the sink. Just took the thing apart and all it had was a marble in a tube (sort of). I took the marble out and it works great. Of course no built in back flow preventer now.

Last camper back flow was cracked and flood bathroom. Ordered new unit and it would not flow until I did same, removed the spring and ball.

Fireman1317 · 08-06-2017, 07:51 PM

I just tried to use the black tank flush on our brand new 3950BR today and surprise surprise it just sprayed water back out. I'm tempted to find the back flow preventer, remove the check valve and use a backflow preventer at the hose connection.

PeteandJoan · 08-07-2017, 09:31 AM

Quote:

Originally Posted by Fireman1317

I just tried to use the black tank flush on our brand new 3950BR today and surprise surprise it just sprayed water back out. I'm tempted to find the back flow preventer, remove the check valve and use a backflow preventer at the hose connection.

By installing it that way at least you will not get the inside of your RV flooded if and when it fails....and it probably will fail. mine was only a few months old when it started leaking. Last year at Goshen Rally Keystone sent me over to Tiara RV and they replaced it and that one failed 3 months later. So far so good on this last one...fingers crossed. Keystone should install the brass model to begin with.

cw3jason · 08-07-2017, 07:43 AM

You can remove the valve and push on the check valve. if it moves up and down, it could be installed backwards not allowing water to flow. if it doesn't move, it is simple to replace.

GLENNCALVIN · 08-08-2017, 03:12 AM

Had the same problem on my 2017 293 RK. Found the valve under the sink in the bathroom, I removed the guts of the valve and sealed the top of the valve. works fine

Retire 2022 · 08-08-2017, 06:49 AM

I had the same issue with our 3811ms the first time I attempted to use the tank flush connection. I got frustrated that the when I connected the hose to the black flush tank valve the water sprayed out around the connection back at me. Luckily my son (26 yr. old) who suggested checking to see if there was a rubber washer in the flush connector. There was not; put in a hose washer with cone screen and NO MORE SPRAYING BACK AT ME. Black tank flush problem solved. Not sure if this is your issue or not but it fixed ours. I couldn't believe that is all it took to fix the issue. Works great now.

Former StClairSailor · 08-08-2017, 09:55 AM

For those of you who haven't had the anti-siphon valve fail yet, don't forget to put a pressure regulator on the hose to the tank flush. If not, you will blow the anti-siphon valve when hooking up to a hose faucet with more than 60-65 psi. And if it does get blown you will have a significant leak. First hand experience. lol Rather than putting in another one, I bypassed the valve and use a backflow preventer on the end of the hose I use for the tank flush.

whutfles · 11-23-2017, 12:02 PM

We have a 2012 Montanna Mountaineer 326RLT with anti-siphon valve under our bathroom sink. After we bought the RV new we used it a few times late in the year for 2 or 3 day stays and emptied the tanks each time as we left the park. No issues. Then we took it to Texas for the winter and put a wye on our city water faucet with one hose going to the black tank. After emptying the tanks I just turned off the small valve on the wye at the city connection and left that hose connected at the RV and to the wye. After about 2 or 3 dumpings I noticed water in my garage. It was comming from the bathroom floor above the garage dripping from a water line that went up into the floor. I went inside the camper, under the bathroom sink cabinet and found the water comming from the anti-siphon valve. I called the dealer and he offered to send me another valve. But he asked me to do a test. He had me turn on the water to the backflush and observe if I had any leaks - I didn't. Then he had me turn the water off at the wye - performing the same operation I had done earlier. We waited for about 5 minutes and then all of a sudden here came the drips thru the floor, from the same hose under the bathroom sink. Then he had me perform the test again and after backflushing, then turning off the water at the wye, he had me disconnect the hose from the wye and let the water drain out of the hose near the wye. Walla, no leak 5 minutes later. The technician surmised that after turning off the water at the wye, the pressure in between the hose and the anti-siphon valve will slowly leak out. When the pressure gets so low that it cannot force the diaphram in the anti-siphon valve against it's opening, it will allow the water in the hose to bypass the seal and leak out into the cabinet below the sink.

He explained that the anti-siphon valve's purpose is to prevent contaminated sewage from traveling thru the backflush hose back into the city water water line. I asked how it did that? He said there is an opening in the valve (in the top bell part). He said if the tank got too full it would force a diaphram to close off the incomming hose from the city side and allow it to run out into the cabinet under the sink. But when the water comes from the other direction (from the city line) the same diaphram closes off the opening in the bell and allows the water to follow the line into the tank. So when the water pressure leaks by the diaphram after the water is shut off, it runs out into the cabinet rather than following the hose into the tank. Now this is not how I would have designed an anti-siphon valve to work. I think I would have added a drain hose to let it go thru the floor and drain out onto the ground rather than contaminate my bathroom and garage, but no one asked me.

So I now have my hose connected to a wye at the city water faucet running to my backflush connection. The other exit of that wye feeds my fresh water. But near the camper I installed another wye in the backflush line with shutoffs on each end of that wye. One exit from that 2nd wye goes to the backflush and the other exit has nothing connected to it. When I'm done draining, I cut the water pressure on the wye at the city faucet. Then I immediately open the valve on the wye near the camper that has nothing connected to it which allows the water in the line to drain onto the ground. Have been doing this for 8 years and have had no leaks from the anti-siphon valve since.

So when you think your anti-siphon valve is bad because it is leaking, immediately drain your hose after cutting the water pressure and see if it still leaks. Probably won't. I give all the credit for this fix to the technician from Leach Camper in Lincoln, Ne who was patient enough to stay on the line with me to listen to my problem, to think it out and find a solution.

**scottz** · 11-23-2017, 08:39 PM

Quote:

Originally Posted by whutfles

He said if the tank got too full it would force a diaphram to close off the incomming hose from the city side and allow it to run out into the cabinet under the sink.

So when the water pressure leaks by the diaphram after the water is shut off, it runs out into the cabinet rather than following the hose into the tank.

Are you saying that it is a normal occurrence for either raw sewage or water from the black tank flush connection to leak out inside the unit? I find this hard to believe.

I think an overfull black tank would just cause the toilet to back up.

**Carl n Susan** · 11-23-2017, 12:54 PM

The anti-siphon valve expects the incoming water to disconnected and the pressure eliminated so it can drain the residual water in the line. Leaving it connected to the water source does not allow the water to flow backwards and out.

Leaks from the valve are the proven result of leaving pressure in the input line. Your improved wye system effectively produces a path for the water to drain.

mhs4771 · 11-23-2017, 04:46 PM

Leaving the Back Flush line connected can cause other problems. Friends left theirs connected and noticed a few days later their Black Tank was full, seems the shutoff on the Y didn't close completely, which could have resulted in a really stinky situation.

whutfles · 11-23-2017, 06:08 PM

I can see that happening. We've had the unfortunate experience of the black tank plugging up. With the help of a traveling repair service, we learned how to use a reverse flo connection. The problem started with a couple of stays in state parks that didn't have sufficient water pressure in the backflo, uneven surface at the dump station and not being able to visualize when the tank was empty, just going by sound. When we connected the reverse flo tube in our drain, it was clear plastic and we could see what was comming out. So there is a 2nd wye in our backflush hose that goes to the reverse flo connection. So when I am not dumping, the wye is off at the city water, it's off to the entry of the wye that goes to the backflush and to the reverse flo and the other 2 ends of that same wye are off also. So there are 3 valves turned off before it can get into the backflush hose. And on about an annual basis i replace these wyes.

When I pull the black taink valve, and after it initially drains, I faithfully refill the black tank with water by closing the drain at the reverse flo connection and allowing water to run back into the drain and into the black tank from the bottom while at the same time run water thru the backflush sprayer which is filling the tank from the top. I count to about 200 and then open the reverse flo valve to drain. This probably fills the black tank about 1/2 to 2/3rds. A considerable amount of waste will come out. I repeat this a 2nd time. Still more waste comes out but less than previously. Then after done draining, I open the stool valve and hold it open to about a count of 80 putting some water back into the tank. During this time I put 2 tbsp of enzyme powder and about a 1/2 cup of dawn dish soap. It's amazing how this stuff slithers out when you drain it again. Have never had a plug since. Along with this process, the secret is using sufficient water each time you flush paper.

**scottz** · 11-23-2017, 08:49 PM

I also don't fully understand the purpose or need for this anti siphon device unless just to satisfy a code. I don't see how liquid in the un-pressurized black tank could ever make it's way into the pressurized water hose.

And why an anti-siphon device with an air vent inside the trailer instead of a simple check valve?

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