Black Water Flush slow

[Jefird]

New-to-me 2005 Voyage F33. I’m not new to RVing: we bought a brand new 1994 Sunrise in Alaska, totaled by water damage recently.

With my Sunrise, when I pulled the valves I would encounter an energetic, satisfying whoooosh, which would in a couple minutes slow to a trickle. Black water, sink water, gray water, it was all done in a few minutes. But I bought the Sunrise new, made sure the tanks were full when I dumped. Not sure previous owner of this Voyage knew to do that and not easy about what’s in there now.

With this, I pull a valve and wait. Just a lethargic trickle even when the tanks are near full. I can see the material coming out through the clear plastic elbow, but it comes out much more slowly than in my Sunrise. 15 minutes or more and I close it up, still not sure tanks are empty. I have cleaned it several different ways: Camco Rhino Blaster, on board black water flush, baking soda and vinegar. Drive around with 10 pounds of ice cubes.

Any ideas better than pulling the valve and running my snake through it?

[Jim_HiTek]

Sure sounds like some nasty stuff is clogging the outlet pipes. PO had really long hair and a lot of it maybe?

I would think you might need to try some water softener, Dawn liquid soap, some bleach, let it fill, drive around that way for a while, and then use the wand.

There are services that will come and blast your tank out with high pressure steam. Hope it doesn't come to that.

[Morich]

Any chance you've found a solution? There are some less extreme methods to go about clearing a clog. One that is down and dirty (way dirty!) is to use a lid with a hose connection on it and force water back up into the holding tank. Since the load all comes downhill, running water fast back up into the tank can work to dislodge anything that is hanging up on some small point or connection.
The dirty part? When you have flushed it out, figure out how to clear ALL of the drainage before you take the lid off!! You can drain the liquid out through that hose connection but there going to be quite a bit that will not go through the hose and you will NOT want it hitting you in the face. Separates the men from the boys type thing?

[Jefird]

Thanks for your replies, guys.

Where this stands now is, I’ve dumped a full box of baking soda down the toilet, followed by a gallon od vinegar and two gallons of warm water. I’ve seen such a brew unclog stubborn drains, maybe it’ll work here as well.

[Johnnyg]

I attached a pic of a gate valve with fresh water port up stream of the valve to push water up into the clog. Not nearly as challenging as the cap but a little cleaner.
Also might check if the vent is clogged. One easy way to check is to have someone hold the toilet open while dumping the water to see if the flow increases.
Good luck and let us know what you find.