Toilet malfunction

[ThorMan]

When I flush the toilet in my MH it bubbles back when first flushed open. I assume it is a venting problem. Where do I look to solve this issue?

[dougrainer]

Most common cause is the Toilet 3 inch down tube is too far into the tank. 2nd Most common cause is the 1.5 inch VENT pipe is inserted too far into the tank almost touching the bottom. Once enough water gets in the tank that vent tube cannot exhaust air. Doug

[ThorMan]

When I get home I will put a ladder up to the vent and check it out. This MH was purchased new two years ago, and has done it before. This is the first time out with it this season, and it worked perfectly for the first tank full. I wonder if it came from the factory with some kind of plastic covering to keep bugs out, and that was not removed by the dealer when prepping it?

[opnspaces]

Does it bubble every time you flush? Or does it start bubbling as the tank fills? Has it bubbled since you bought the RV, or is this something recent? I can think of only a few issues that could cause this.

Empty the tank, turn off the water, open the flush valve and look down the hole. If you can you see the bottom of the tank is it clean? It should be clean if you just dumped the tank. If there is a bend in the pipe on the way to the tank is there anything in the bend that needs to be cleaned out? Now fill the bowl and flush, does it bubble?

As suggested check the roof to see if the vent is plugged. You will have to scrape out the caulking over the screw holes in order to remove the cover.

With the roof cover off check to see if the black plastic vent pipe has slid down into the tank, or is it all the way up to the level of the roof. If the pipe slides down into the tank it will submerge the end of the pipe in liquid and prevent venting. You might be able to get something in the pipe and pull it back up level with the roof deck.

Put a garden hose in the vent pipe and have someone turn the water on while you listen. You should hear the water hitting the bottom of the tank. If you don't hear the water hit the bottom, or if the pipe just fills up you have a clog.

If the pipe is plugged you're going to have to figure out a way to clear it. The hose might do the trick. Or maybe get a 2 oz lead fishing weight and a spool of string. Lower the weight down until you hit the clog. Now pull up about a foot and let the weight fall. Have someone go under the RV and listen to see if the weight is hitting the bottom of the tank.

[ThorMan]

ScottG wrote:
You don't leave the black tank vavle open do you?

No, I closed it after emptying it last.

[ScottG]

You don't leave the black tank vavle open do you?

[DutchmenSport]

Roof. Pull the vent cap off. See if bees or wasps have built a nest and clogged the pipe. If it looks clear, get an old garden hose and shove it down the vent pipe. If it reaches the bottom it's clear, something else is going on then.

While you have that hose there, you might as well turn the water on and clean your tank out too! If there are any clogs or poop pyramids, this may help break that down.

You could also try shoving the garden hose down the toilet. I'm assuming yours does not drop straight into the holding tank, but goes down a pipe, probably at an angle, and then into the tank ... ker-plop!