The dreaded potty burp, can't eliminate it

[Wind_Surfer]

Long time RV'r and have dealt with the potty burp before but this time I can't figure it out. Interestingly the pipe connecting the toilet to the tank would sometimes back up implying a 'pyramid'. I would take the cleaning brush and 'push' at the water and it would clear. Pipe to tank is about 3 feet in length.

I have (gently) snaked both the toilet and vent. As far as I can tell there is no "PYRAMID" and the vent is clear.

We have always used plenty of water during usage and have had this rig for 5 years.

Thoughts?

[Old-Biscuit]

Tank burps when empty after dumping and cleaning.


That is a blocked/obstructed VENT line.

UNLESS toilet line to tank is NOT emptying

Go to Home Depot/Lowes/ACE Hardware and purchase a 'Drain Blaster'
Screws onto a garden hose, push it down toilet line and turn on water. It will expand to size of line sealing it and then blast away with high pressure clearing out line.
Then if toilet stills burps.try it on vent line from roof

They have 3 sizes...get the 1 1/2" to 3" model

[Wind_Surfer]

It does not appear that the vent pipe has moved. I went onto the roof to snake it and all looked normal.

Are the vent pipes just clear pipes without any type of one way diaphragm type of valve?

The toilet pipe does make two 45's but snaking the pipe did not bring back any tissue or 'other' things.

Tank burps when empty after dumping and cleaning.

[Beaker]

My old fifth used to do this. It had a curved pipe and when getting full it seemed like the tissue would start backing up in the pipe. It would burp and when this happened I know it was time to dump although if I "pushed" it like you did, I would get a couple more days.

[gbopp]

You said the vent is clear but, did the pipe slide down into the tank?