Cleaning the black water tank

[MagillaGorilla]

I have an 06 Holiday Rambler Admiral. I have owned it for 3 years and the black water tank has never drained completely.

Out side, where you dump the tank, there is a hook up for a hose that is supposed to flush the tank. When I hook up the hose and turn the water on nothing happens. I have the tank drain open and no water comes out.

The tank gauge always reads 1/2 full and there always seems to be something in the tank when you look in it.

I tried putting in 20 pounds of ice on my last trip. I read that it would slosh around and free up anything that was caught in there. It seems to have made no difference.

Anyone out here have any ideas?

[kofire]

Id fill it up with dish soap and maybe some type of unclogging chemical. Then go drive around for a bit. Then drain it and go from there.

[dodge_guy]

Also, because the tank always has a bow or low spot in it, it will always look like it has liquid in it. (Edit, I see that was covered in the last post) The gauge reading full is probably due to toilet paper stuck on the sensors. Once you get the tank flusher working the gauges should read correctly. All they are is terminals that provide an electrical path through the water. There are 4 or 5 terminals depending on how your gauge reads. I'm betting it empty and the gauges are giving false readings.

If you can't get the rinser working they do sell a wand you put down inside the toilet that has a sprayer on the end. It's a bit more intrusive and possibly messy but they work!

[Lwiddis]

On the last dump of a trip I elevate the side opposite the drain two to three inches.

[troubledwaters]

You need to actually verify the tank is not draining completely.

"The tank gauge always reads 1/2 full and there always seems to be something in the tank when you look in it."

Tank gauges are notoriously wrong. And looking in the tank all you will see is "wetness". Stick something in the tank so you can actually measure how much water is in it. A small amount on the bottom is no big deal (1-inch ±). Several inches (2 or more) is cause to figure out what the problem is.

A bow in the bottom of the tank is quite normal and may hold an inch or two of water that will never drain. More than that may indicate something is blocking the outlet (or it may indicate you have a larger bow in the bottom - on an eleven year old unit that may be entirely possible).

[Old-Biscuit]

The 'spray nozzle' holes are plugged up
OR
The 'anti-siphon vacuum breaker backflow' device is not opening


'Vac Breaker......typically under bathroom sink

'Nozzle'....thru side of black tank


Disconnecting lines at Vac Breaker and then pouring CLR, Lime away, etc down hose to nozzle and letting it sit MAY free up clogged holes.
Some nozzles (if accessible) can be removed from tank





Hose connecting to bottom is from the hookup on side of RV
Hose connecting to the side is going to nozzle




ICE.......
Doesn't do anything. It's just expensive water


Being a 'used' rig.....unknown history buy a bottle of UNIQUE Digester
Treat black tank and then drain/flush to remove any left behind stuff

[MagillaGorilla]

2oldman wrote:

MagillaGorilla wrote:
Out side, where you dump the tank, there is a hook up for a hose that is supposed to flush the tank. When I hook up the hose and turn the water on nothing happens.

Ok, is there a twist valve you need to turn?

Not that I see. Its just a 3/4 inch hose connection

[2oldman]

MagillaGorilla wrote:
Out side, where you dump the tank, there is a hook up for a hose that is supposed to flush the tank. When I hook up the hose and turn the water on nothing happens.

Ok, is there a twist valve you need to turn?