Black Tank Flush weirdness.

[TayaraTravel]

On a 2017 GT: On last stop returning from a long trip we decided to give the "Black Tank Flush" a try. Followed directions to hook up a garden hose to the connector inside the dump access door and turn on. (Black tank already emptied by usual macerator pump.) Immediately water (fresh, we are sure) began dripping out along the bottom edge of the van to the left (cab-ways) of the access door. Aborted the action and then flushed the black tank a couple more times the usual way.

Later noted clean water inside van, running out over floor emerging from underneath furnace and refrigerator. I'm guessing the initial flow of water pooled and caught somewhere, and is now escaping as the van is driven.

Any ideas?

On a side note, I later noticed a warning inside the dump access door:

This properly scared me, since I had no idea what a "fullway valve" is. After googling, found out it is just the black water valve by a different name, and the warning is a CYA in case some idiot leaves the hose connected and filling and wanders off to make dinner.

[Lily&Me]

Might check your owners manual for troubleshooting, also call the service department at your dealership.

Good luck.

Maggie

[CDONA]

The black tank flush does not have an inline shore water pressure reducer.
It has been noted from the TT side that the anti syphon valve will blow and flow water into your rig. There are posts on replacing these with stronger other than plastic valves.

I slowly open the shore water valve and listen for the end of air bubbles traveling thru the hose, then slowly open shore water fully.

I think it is the high pressure hit of those air bubbles with the shore water full on that pops the syphon valve.

[TravlinMan]

I also had to look up fullway termination valve and when I learnt what it is, I felt like that sticker had played a joke on me.

[TayaraTravel]

Originally Posted by CDONA

The black tank flush does not have an inline shore water pressure reducer.
It has been noted from the TT side that the anti syphon valve will blow and flow water into your rig. There are posts on replacing these with stronger other than plastic valves.

I slowly open the shore water valve and listen for the end of air bubbles traveling thru the hose, then slowly open shore water fully.

I think it is the high pressure hit of those air bubbles with the shore water full on that pops the syphon valve.

Thanks! Is that a temporary "pop" that goes back to normal when the pressure is removed, or have I permanently popped something open or broken it?

[UKDUDE]

The black tank flush has a valve to prevent black water from escaping out the hose and causing contamination. My guess is that valve has been installed backwards. Airstream is noted for making errors like this.

[TayaraTravel]

I dropped it off at the service center today. The service manager seemed familiar with the problem. We'll see what happens.

[TayaraTravel]

Originally Posted by TravlinMan

I also had to look up fullway termination valve and when I learnt what it is, I felt like that sticker had played a joke on me.

It's right next to the Turbo Encabulator.

https://www.youtube.com/watch?v=Ac7G7xOG2Ag

[Prairie]

I had the same problem. The check valve in the flush line from the hose to the black water tank was cracked. Probably from freezing. It's located behind the microwave. Good luck!

[Titus]

I removed my backflow valve. I have a fitting with a shut-off at the end of the hose. I turn on the water then connect the hose to the Interstate, then open the valve to flush the black tank. Then I shut the valve and disconnect the hose. Thus, I have a manual anti-backflow approach that does not freeze, crack, and flood the interior.

[Boxster1971]

Originally Posted by Titus

I removed my backflow valve. I have a fitting with a shut-off at the end of the hose. I turn on the water then connect the hose to the Interstate, then open the valve to flush the black tank. Then I shut the valve and disconnect the hose. Thus, I have a manual anti-backflow approach that does not freeze, crack, and flood the interior.

Great solution! Thanks.

[thiel]

Three things I've learned on this front:

1) there is no pressure regulator on the black tank flush inlet, so high pressure is a good way to blow the valve.

2) Winterizing procedures seem to ignore the black tank flush system, so many problems seem to be a result of freezing.

3) in my case (i had a similar problem in my trailer) i opened up the access to find that the black tank flush connection to the interior plumbing had not been screwed on -- it was completely loose. Tightened it and it seems fine now.

[mssciteacher]

Had the same problem with our 2016. Dealer repair tech said the plastic valve blew out so they replaced it with a better metal part. The same thing happened the next time we were out. Turns out they INSTALLED IT BACKWARDS and never bothered to test it (although they claimed they did). Don't know yet what the long term result will be having water covering our floor now multiple times.

[thiel]

BTW... I did some black tank flushing this morning and it was quite rewarding. I'd be willing to bet I had the cleanest black tank in the whole campground

[MelGoddard]

Originally Posted by TayaraTravel

It's right next to the Turbo Encabulator.

Notice how he keeps a 'straight face' during his delivery??

[MelGoddard]

The 'Turbo-Encabulator' influences the 'Riostatiscope' that attached to the 'Fritzonaires.". It's purpose is to influence the 'Riostatiscope' to 'Taselate' the action of the 'Gizmofreeny'!

[RandyNH]

Originally Posted by Titus

I removed my backflow valve. I have a fitting with a shut-off at the end of the hose. I turn on the water then connect the hose to the Interstate, then open the valve to flush the black tank. Then I shut the valve and disconnect the hose. Thus, I have a manual anti-backflow approach that does not freeze, crack, and flood the interior.

Originally Posted by Boxster1971

Great solution! Thanks.

Just so I understand correctly, there is a backflow preventer in the line which keeps the bio hazard materials from traveling back down the line to the water connection point and cap, you've removed it because you installed a shut off valve on your hose (don't they all have shut off valves, you know the handle) so now any splash or overflow that makes it into the line is sitting there waiting for you to remove the cap and connect your hose?

[73shark]

Originally Posted by RandyNH

Just so I understand correctly, there is a backflow preventer in the line which keeps the bio hazard materials from traveling back down the line to the water connection point and cap, you've removed it because you installed a shut off valve on your hose (don't they all have shut off valves, you know the handle) so now any splash or overflow that makes it into the line is sitting there waiting for you to remove the cap and connect your hose?

He has a shutoff valve on the end of the hose that he has connected to the black water flush connection. He shuts off the water before disconnecting the hose thereby preventing any contamination of the water in the hose.

[AirstreamCSH]

As a follow up, I had a similar problem with a 25FB that was new. Turns out the factory crimped one of two crimps on the elbow so water poured into the pan plus under the shower. Wasn't a valve problem but a simple quality control one.

[thiel]

On this subject: how many of you use a dedicated hose for black tank flushing... vs just using your fresh water hose?