Toilet air lock

thank you for all your responses. We will check them out and see if this clears things up.

Sounds like the toilet bowl has something like a pencil or pen or something like that stuck in it. What happens is the object tends to catch the toilet paper and it builds up til you plunge it freeing the paper but not the object then the cycle starts all over again. Try looking up through the the bowl with a small inspection mirror and you may be able to see whats causing you blockage.

PS yes I'm a plumber... :)

No bubbles when you first start using it?
Bubbles after a while and then you plunge it and no more bubbles?

Try using more water.
Solids tend to pile up at the bottom and eventually up the tube to the toilet. The sudden rush of "stuff" down the tube causes the trapped air up the tube causing your bubbles or burp.

More water in the tank will help those "solids" to breakdown and float away.

Of course, you could have the dreaded pyramid or clogged air vent, but if it acts as above probably not.

Old-Biscuit wrote:

Vent line is blocked due to poop pyramid buildup inside tank

This one is it 99.99 percent of the time. Chris

search for poop pyramid and read away.

Easy fix with the wand from Wally world that has the whirly bird on the tip of it.

That will probably fix it and you won';t have to start crawling all over it to no avail.

I had that problem and it went away when I used more water when flushing the solids.

If you want to get your black water tank clean, the easiest and fastest way, here is what you do.

Buy three bags of ice cubes. Fill the tank half full of water and dump the ice cubes down the toilet into the tank.

Drive your rig until the ice cubes melt. When you dump the tank the ice cubes will have scoured all the hard deposits from the tank and they will flush out down the drain.

If you have a vent problem and the pipe has not slipped down, this might help.

Black tank vent is getting plugged so tank is venting thru toilet when you flush

Tank level high blocking off bottom of vent line
Vent line has dropped down inside tank and is getting blocked
Vent line is blocked due to poop pyramid buildup inside tank
Vent line is blocked due to birds nest/debris inside at roof line.

Vent line is blocked.......you get to figure out what is blocking it

You have a pile! Chris

My guess would be an obstruction in the vent pipe or the pipe has slipped or installed below the level of the waste in the tank. Does it do it with the tank empty?