Black water flush repair

[MDPD]

This explaination of the repair I made to my black water flush in my '06 36' Journey is a little lenghtly, and I unfortunately didn't have a camera handy but I hope this helps someone with the same issue.
When attempting to flush my tank last week I found that the water would not run in and later found that the bathroon and part of the living room were flooded. I checked the threads on this forum and then called Winnebago. The tech person I spoke to advised me that the back flow/vacuum breaker had apparantly malfunctioned and I would have to change it. Believe it or not, the faulty valve is inside the wall seperating the bath from the living room and the only way to replace it would be to remove the cabinets in the toliet area which would necessitate removal of the toilet or to cut an access hole in the living room wall behind the mirror. All this would be many hours of labor and damage the wall. I devised an easy repair that I will attempt to describe.

I removed the white panel in the valve/hose compartment which exposed the spray inlet to the tank.
I removed the pex fitting from the black water tank and replaced it with a 1/2" insert elbow which is threaded on one side and barbed on the other.
On the top of the existing hose connection where your rinse hose would attach I attached a 1/2" PVC check valve to which I attached another insert fitting but straight instead of an elbow like placed on the tank itself.
Between the two barbed ends I attached a piece of high pressure clear hose and tightened them with hose clamps. I cut the hose long enough to make a loop that is higher than the tank as a second backup to the check valve to eliminate any chance of black water backing into the hose fitting.

Works like a charm and the total for the materials at Ace Hardware was under $20 and I didn't have to destroy the coach. The total time it took was under two hours (including downing 2 beers) and that included the trip to the store.

I hope I described this well enough and it saves somone a lot of time and money.

[skigramp]

Two comments:

1. It sounds like you figured out a replacement technique for the defective check valve on the back flush for the black tank ...
2. I worked on a farm a couple of summers when I was growing up ... when farmers irrigate row crops from a lateral (their name for a small ditch) they use siphon tubes ... when a siphon tube is filled with water it will carry water up over the side of the lateral and onto the crops as long as the crop is lower than the level of the water in the lateral ... the point of this is that the "loop" itself will do nothing to prevent back flow once your hose is filled with water !!!

[royinflorida]

On my Horizon I discovered that no water was going into the tank from the black water flush fitting. The people at Lazydays spent several hours trying to find the check valve you mentioned. It was in the wall next to the bathroom door alongside the toilet. Seems that Winnebago had installed it backwards when they built it. The tech said he had seen it happen before and even thought the coach was 5 years old, no one had discovered it since they just assumed it worked when the flushed the tank. Thankfully mine didn't leak and LD covered the cost of the repair.

[AFChap]

One time several years ago, when I turned the water outside to flush the tank it sounded different, then I heard screams inside the coach and water streamed out the compartment ceiling immediately in front of the water bay. I just happened to have that door open too. I turned the water off, checked everything, then slowly turned it back on and everything worked as normal. It has never happened again. My theory at the time was that I was hook to a very high pressure hydrant w/o a pressure regulator, and that applying all that pressure very quickly caused some sort of malfunction. But I never could picture how there would be a way for water to get out of the water line. Why would that input water line need a vacuum breaker? Seems it would be a direct solid line into the tank. Check valve yes, but why a vacuum breaker? There is already a vacuum breaker for the black tank under the throne room sink.

[DAN L]

Quote:

Originally Posted by MDPD This explaination of the repair I made to my black water flush in my '06 36' Journey is a little lenghtly, and I unfortunately didn't have a camera handy but I hope this helps someone with the same issue. When attempting to flush my tank last week I found that the water would not run in and later found that the bathroon and part of the living room were flooded. I checked the threads on this forum and then called Winnebago. The tech person I spoke to advised me that the back flow/vacuum breaker had apparantly malfunctioned and I would have to change it. Believe it or not, the faulty valve is inside the wall seperating the bath from the living room and the only way to replace it would be to remove the cabinets in the toliet area which would necessitate removal of the toilet or to cut an access hole in the living room wall behind the mirror. All this would be many hours of labor and damage the wall. I devised an easy repair that I will attempt to describe. I removed the white panel in the valve/hose compartment which exposed the spray inlet to the tank. I removed the pex fitting from the black water tank and replaced it with a 1/2" insert elbow which is threaded on one side and barbed on the other. On the top of the existing hose connection where your rinse hose would attach I attached a 1/2" PVC check valve to which I attached another insert fitting but straight instead of an elbow like placed on the tank itself. Between the two barbed ends I attached a piece of high pressure clear hose and tightened them with hose clamps. I cut the hose long enough to make a loop that is higher than the tank as a second backup to the check valve to eliminate any chance of black water backing into the hose fitting. Works like a charm and the total for the materials at Ace Hardware was under $20 and I didn't have to destroy the coach. The total time it took was under two hours (including downing 2 beers) and that included the trip to the store. I hope I described this well enough and it saves somone a lot of time and money.

imo you are good to go IF you use an external one way anti syphon valve such as the small item in this illustration when you hook up a hose to flush your black water tank.
that is what i do.

RV Hydro Flush - Product - Camping World