Toilet bubbles when flush help

[E12Cheng]

Flush the toilet and it bubbles up with bad gas smell. looks like my vent is clogged not allowing air to escape the tank when I flush. Any suggestions of where I would find the vent valve? I have a 2020 3931 FB and the smell and bubbles is only happening in the forward bathroom. The 1/2 bath is fine. That you for any help here.

[twindman]

I don't have much experience on the bubbling thing, but have read many posts about don't dump until it bubbles (for those who want to fill it up and we know the gauges don't work). So to me it sounds like you haven't dumped both tanks (assuming there are 2). Since it is a 2020 model, I thought perhaps you were somewhat new with rvs or at least this model.

[E12Cheng]

Thanks but no, I dumped the tanks this morning. Dumped the black and then the grey to clean the line. I left the grey open so we could take a Hollywood shower. I thought that maybe that was the problem so I closed the grey tank valves and still have the bubble problem. I would think that the grey and black tanks have different relief vents as they are different tanks.

[twindman]

I wasn't clear enough. I meant did you dump both Black tanks. Not sure you have two, but some models do. People talk about 4 tanks - 2 black and 2 gray. Good luck.
I am sure someone will pipe in here soon.

[E12Cheng]

Thanks yes I dumped all 4 tanks.

[BB_TX]

There is no vent valve. There should be a vent pipe from your black tank up thru a wall and exit on the roof with a mushroom cap. If you look on the roof directly above your black tank you should see it. There will be 2 or 3 other similar vents up there also in different areas. You should be able to remove the cap and run a snake down the pipe to the tank.

Being a 2020 I think I would be consulting my dealer to solve the problem.

[E12Cheng]

Thank you for the reply. I thought they may have a check valve or something in the line. I will take a look in the morning to snake it. I'm in Florida and my dealer is in Alabama. if it is something easy I will give it a shot.

[grass man]

I had that issue on my 3931 in the same bath. It was clogged and only draining slow. I turned the water to toilet off and dumped several hot pots full of water down the toilet and it worked great after that. I believe this toilet seems to clog easier than the 1/2 bath one. Maybe the pipe has a bend in it and it gets caught easier, don't really know. Hope the hot water helps.

[mtlakejim]

To be sure your vent pipe is connected to the tank, you can use a water hose to run water down the vent pipe from the roof. You should be able to turn off the toilet supply, open the toilet valve and hear the water going into the tank. It wouldn't be the first time that someone at the factory forgot to hookup a line to a tank....


As a possible remedy for the future, make sure you use a LOT of water to flush solids. Not using enough flush water is probably the #1 mistake most campers make related to the black tanks.

[psomers]

Put a clear fitting on sewer connection before the dump hose. Turn on flush to flush tank. Make sure at the clear fitting that water is flowing.
My unit has a 90 degree fitting and then about 4 feet of almost flat run of sewer plumbing. I'm always having trouble dumping. I use one of these with good success: This is the whttps://www.amazon.com/Camco-Rhino-Blaster-Sewer-Rinser/dp/B00T36KRS2/ref=sr_1_9?keywords=rhino+rv+clear+connection&qid= 1584453258&s=automotive&sr=1-9orse dumping camper I've ever had

[MT167]

We have a 2013 3900FB and experience the same issue at times. You probably have a pile of poop and paper built up where the toilet dumps into the tank. It generally happens when we have been parked for 3 or 4 months, or when I don't get the black tank drain valve closed all the way. To get rid of it, use a good plunger to clear the toilet's drain pipe, add lots of water to the tank, raise the front of the trailer as high as possible with the landing gear, open the black tank drain valve, turn on the black tank flusher and let it run until the water runs clear. The toilet drains into the black tank on the opposite end of the drain and not using enough water and a good black tank treatment will let the solids settle out and block the toilet drain. When you close the black tank valve, make sure it is not leaking. If it is, the liquids will drain out leaving the pile of poop. Re-level the trailer, add at least 5 gallons of water to the tank (10 would be better), and add a good black tank treatment to the tank (one that will dissolve solids). Hope this helps.

Keith

[E12Cheng]

Thanks to everyone for the good advice. I was on Cumberland Island yesterday and today was a travel day. When I set up my camper today no bubbles and no bad smell. I guess the bumpy roads from St Mary's to Macon must have cleared the clog. My rig was is storage before my trip so that could have been part of it. I will take everyones advice and ensure I have a lot of water in my black tank. I use a product called "Happy Camper" for my tank treatment and I think it works pretty good. Again thanks everyone

[David Leak]

You have to be careful when using gobs of toilet paper, it will sometimes stick in the pipe under the toilet when it gets a film built up where it turns down towards the tank. If it does stick the toilet will spit water and so forth completely out of the top of the toilet. You may have to get the garden hose after it and clean the pipe out.

[Minitrbo]

I have the same starting recently in a high country 320MK. One big bubble when I flush. We use minimal toilet paper. Since it started we put water in the black tank, dumped it, hooked up the flush hose and ran it until it was running clear. Also ran a hose into the vent. Since then we have dumped and flushed again. The bubble continues. Oddly to my logic, if I hold the toilet flush open for ten seconds, the smell is very slightly bad, not like there is poo and whatever rotting in the tank. No other problems with the toilet.

[David Leak]

You can turn all the water off, Both outside and the pump if on, then hold the toilet valve open and look down the pipe under the toilet with a flash light, you can see if it needs to cleaned it out. Crud attaches to the bend of the pipe, which can be cleaned out with a garden hose with a good nozzle. I’d flush the black tank first.

[margerush]

I don't know where in Florida your located but we've had really good knowledgable service from the Camping Worlds in Ocala and Tampa. They should be able to work on your Montana. You should be under warranty

[paulinbaja]

If it has done this since new there may be a vent problem. Most likely the vent is clogged and checking it out will correct the problem. If since new see the dealer, if it started later run a snale down the vent to the bottom and you should be "Good To Go".

[Rondo]

Sounds to me you have the proverbial "Pyramid" in the black tank and not using enough water when flushing the toilet. You can fill the tank some and add some regular fabric softener to the tank (cup to two cups) and add more water to the tank and then let it sit for about six hours or more. This should help to soften up the "pyramid" and the flush the tank using both the OEM tank flush as well as sticking a hose down the toilet to break up the mound formed in the tank. You may have to use a pulsating of the water to break the mound up and get it to flow out the outlet into the sewer. I also use a back flush attachment on the end of my outlet that sends a stream of water up the pipe into the tank when I have done. It is a clear section with a valve on it to connect a hose too.

[Ruffuslike]

'I had that issue on my 3931 in the same bath. It was clogged and only draining slow. I turned the water to toilet off and dumped several hot pots full of water down the toilet and it worked great after that. I believe this toilet seems to clog easier than the 1/2 bath one. Maybe the pipe has a bend in it and it gets caught easier, don't really know. Hope the hot water helps.'
So, don't you afraid one day hot pot of water won't help?

[rohrmann]

What ever you do, DO NOT snake any lines in your rig. The plumbing and tanks are not as strong as you would find in a home, and there is the danger of puncturing a tank.