2017 Phaeton KQH Black Tank Flush Issue

[APlusParts]

i cant get water into my black tank to flush it after i dump out my last rv was simple i hooked up the hose and opened the valve turned on the water and never had a problem. this rv i dont see a valve anywhere and when i hook up the hose and turn it on no water goes in the tank it sometimes blows the hose off because its clearly closed i guess my question is how do i open the black tank flush valve?

[Lt Dan]

There is no valve and it's a common problem with the flush sprayer. Stuff gets in the nozzle holes unless it's used frequently and dries up. The only way to fix it is to remove the spray head and drill the nozzle holes out slightly larger. The spray head is accessed by removing the panel on the passenger side where the gravity fill is located. Use a thin Phillips screwdriver to remove four screws on each side and the panel will come off. It's not heavy, just bulky so best done with two people. The gravity fill tube is just held on with a hose clamp. Be sure to put some masking tape along the edges of the rear gap to prevent scratching the paint (don't ask how I learned this one). The only other thing that could be blocking flow would be the backflow preventer which should be located in a bathroom or cabinet near the wet bay high up inside the cabinet.

The spray head is attached to the top of the tank with a few screws and sealant. The hardest part of the whole repair is removing the panel. Below is what you are looking for.

[APlusParts]

Originally Posted by Lt Dan

There is no valve and it's a common problem with the flush sprayer. Stuff gets in the nozzle holes unless it's used frequently and dries up. The only way to fix it is to remove the spray head and drill the nozzle holes out slightly larger. The spray head is accessed by removing the panel on the passenger side where the gravity fill is located. Use a thin Phillips screwdriver to remove four screws on each side and the panel will come off. It's not heavy, just bulky so best done with two people. The gravity fill tube is just held on with a hose clamp. Be sure to put some masking tape along the edges of the rear gap to prevent scratching the paint (don't ask how I learned this one). The only other thing that could be blocking flow would be the backflow preventer which should be located in a bathroom or cabinet near the wet bay high up inside the cabinet.

The spray head is attached to the top of the tank with a few screws and sealant. The hardest part of the whole repair is removing the panel. Below is what you are looking for.

im very mechanical but im not good with this stuff you said remove the panel on the passenger side buy my compartment where i empty the tanks in on the driver side are you saying i have to go on the passenger side of the rv and remove a panel to get to it? also what is a gravity fill i assume you mean where i fill the water in the tank but i just hook up a hose in the same comparment on the left side by where i empty the tanks? then you mention a back flow preventer so that is something different then the flush sprayer? and this should be in the bathroom in a cabinet? im sorry to ask so much and i really appreciate your help i have had this rv since august last year and i have never flushed the tank because i have not been able to

[APlusParts]

Originally Posted by Lt Dan

There is no valve and it's a common problem with the flush sprayer. Stuff gets in the nozzle holes unless it's used frequently and dries up. The only way to fix it is to remove the spray head and drill the nozzle holes out slightly larger. The spray head is accessed by removing the panel on the passenger side where the gravity fill is located. Use a thin Phillips screwdriver to remove four screws on each side and the panel will come off. It's not heavy, just bulky so best done with two people. The gravity fill tube is just held on with a hose clamp. Be sure to put some masking tape along the edges of the rear gap to prevent scratching the paint (don't ask how I learned this one). The only other thing that could be blocking flow would be the backflow preventer which should be located in a bathroom or cabinet near the wet bay high up inside the cabinet.

The spray head is attached to the top of the tank with a few screws and sealant. The hardest part of the whole repair is removing the panel. Below is what you are looking for.

i just watched a video i think i understand now the first part is the preventer which stops the back flow then that goes into the spray nozzle its either one of those 2 my only question is where is that panel that you are talking about to accent the spray nozzle the preventer should be in the bathroom i think?

[Lt Dan]

Yes, the access panel is on the opposite from the wet bay. It's the only panel that doesn't have a door handle. A gravity fill is the little locked door on that panel where you can fill the fresh water tank with a garden hose.

The back flow vacuum break valve will be located high up under a cabinet and looks similar to below. It's used to keep water from flowing backward from the black tank flush nozzle.

[APlusParts]

Originally Posted by lt dan

yes, the access panel is on the opposite from the wet bay. It's the only panel that doesn't have a door handle. A gravity fill is the little locked door on that panel where you can fill the fresh water tank with a garden hose.

The back flow vacuum break valve will be located high up under a cabinet and looks similar to below. It's used to keep water from flowing backward from the black tank flush nozzle.

thank you

[jlturner]

Originally Posted by Lt Dan

Yes, the access panel is on the opposite from the wet bay. It's the only panel that doesn't have a door handle. A gravity fill is the little locked door on that panel where you can fill the fresh water tank with a garden hose.

The back flow vacuum break valve will be located high up under a cabinet and looks similar to below. It's used to keep water from flowing backward from the black tank flush nozzle.

That’s good info! Wasn’t sure what I was looking for.

Thx Dan

[Shutterbug57]

Originally Posted by APlusParts

im very mechanical but im not good with this stuff you said remove the panel on the passenger side buy my compartment where i empty the tanks in on the driver side are you saying i have to go on the passenger side of the rv and remove a panel to get to it? also what is a gravity fill i assume you mean where i fill the water in the tank but i just hook up a hose in the same comparment on the left side by where i empty the tanks? then you mention a back flow preventer so that is something different then the flush sprayer? and this should be in the bathroom in a cabinet? im sorry to ask so much and i really appreciate your help i have had this rv since august last year and i have never flushed the tank because i have not been able to

I have a 2011 and it has no gravity fill. The panel you are looking for is still on the passenger side. On mine, it is just a blank panel that has no purpose other than cosmetic. Removing that will show the back side of the wet bay. The sprayer that is clogged is on the top of the black tank. On mine it is on the rear top of the tank. You will want some sealant (roof sealant or caulk) to be sure you have resealed the connection to the tank when you are done. This will prevent smells and/or spillage.

If that panel ever gets damages on my rig, I will have it replaced with a door. I don’t open it often, but a door would be infinitely more convenient when I do need to open it. My understanding is that the sprayer gets clogged if you let the tank level get too high. Junk gets in there then hardens. It’s best to use the sprayer each time you dump the tank. That’s not always convenient, but it is preferable to having to service the sprayer, which is a messy job.