Ok who knows there toilet/black tank systems

[StirCrazy]

Ok so the used camper I bought three years ago has and issue I havent been able to track down yet. so the toilet works perfect, tanks are good (I had to change the guts of the dump valve as it was weeping)
but I still have an issue

so when I am driving and pull over to use the washroom or when we get to the campground and I go to use the washroom right away it smells like a outhouse. this goes away and it is fine for as long as we are camping.

so it only happens when I am driving, the vents are closed when I am driving so its not getting sucked in the roof vents, the seal in the toilet holds water, and there is a little water in the bowl when I am driving.

any ideas where I should look next??

thanks
Steve

[StirCrazy]

dougrainer wrote:
Everybody assumes it is Black odor. Maybe, but after 44 years as a RV tech, most of the time it is Gray tank odor. Most people(SMART people) use a Black tank Deodorizer and break down chemical. Very few use a Gray tank chemical. What I do is dump and flush BOTH tanks. Then I install Pine Sol(about a quart) in the GRAY tank and then drive the RV. IF you get Pine sol odor, then you have a Gray tank problem.

I'll try that if nothing else seams to work, only because I can replace a seal while its in my driveway but I need to load the camper to do the test.. I have to wait for my 5th wheel to be fixed and brought home before I can load the camper... I need a dedicated camper truck I think haha.

dougrainer wrote:
1. IF prepped for a washer Dryer, odds are the P trap has NO water and that is the source.

nope its a 1991 slumberqueen camper. no room for them fancy things

dougrainer wrote:
2. Air admittance valves Install a plastic baggy over them and test, OR just replace they do not cost much

same thing, didn't use air atmittance valves on these, runs to short to need them, I was actualy hopingit was somthing that simple when I went hunting for them yesterday.

dougrainer wrote:
3. The down pipe for both the black and gray may not be sealed or installed to the top of the tank. To check fill both tanks to over full. Water coming up into the toilet bowl and water coming up into the shower pan, IF you get water flowing out off the top of the tanks, that is your leak.

I hope its not at the top of the tank as I think I would have to dissasemble 1/2 the camer to be able to reseal them. but the outside tanks and the vents are solid.

We did have a coupe times where there was water on the floor of the wet bath but there was aboslutly no stink or dirty looking water asociated with it so I figured it was a temporary leak even from the supply to the toilet, which I want to look at anyways.

dougrainer wrote:
4. The roof top tank vents, make SURE the 1.5 inch ABS pipe extends ABOVE the roof line and the pipe is sealed where it comes thru the roof. VERY COMMON

I did re-seal around them last summer and bought new caps thinking that would help.

dougrainer wrote:
PS, IF a Black tank odor, the Flange rubber seal may be worn and bad.

this is what I am going to do in the next coupke weeks. starting to get warm enough to work on things and since it is a 1991 camper (even though it looked brand new) it could have a bad seal

[StirCrazy]

Ok so I went out and looked all over the camper there are no air atmittance valves in the camper at all, no places that sugest they were ever used.

Like vents in home plumbing I believe you only have to add a vent if your sink is more than a spicific distance away from the stack.

in my camper the kitchen sink has about 2.5 feet of pipe (if that) then it is in the grey water tank, the other end of the grey water tank is about the same distance from the bathroom sink.

so I guess im back to the toilet seal... its a older camper maybe it is hardened up. I'll change that out then this spring we will find out if it worked.

in the mean times, if you think of anything else I should check let me know.

Steve

[mordecai81]

I had the OP's same issue under the same conditions. Replace the foam floor seal under your toilet. I bet it fixes the problem.

[Bobbo]

dougrainer wrote:
3. The down pipe for both the black and gray may not be sealed or installed to the top of the tank.

My 2017 Airstream has had bathroom odor since new. This past summer, I was at an Airstream Rally at the Mothership (Airstream factory). I had them check the odor out. The vent pipe going up inside the wall had a joint that was not glued.

[stevenal]

I have heard in these forums of vent pipes slipping down, or not installed properly to begin with so they protrude well into the tank. One the liquid rises to the bottom of the vent pipe, they no longer vent properly.

[dougrainer]

Everybody assumes it is Black odor. Maybe, but after 44 years as a RV tech, most of the time it is Gray tank odor. Most people(SMART people) use a Black tank Deodorizer and break down chemical. Very few use a Gray tank chemical. What I do is dump and flush BOTH tanks. Then I install Pine Sol(about a quart) in the GRAY tank and then drive the RV. IF you get Pine sol odor, then you have a Gray tank problem.
1. IF prepped for a washer Dryer, odds are the P trap has NO water and that is the source.
2. Air admittance valves Install a plastic baggy over them and test, OR just replace they do not cost much
3. The down pipe for both the black and gray may not be sealed or installed to the top of the tank. To check fill both tanks to over full. Water coming up into the toilet bowl and water coming up into the shower pan, IF you get water flowing out off the top of the tanks, that is your leak.
4. The roof top tank vents, make SURE the 1.5 inch ABS pipe extends ABOVE the roof line and the pipe is sealed where it comes thru the roof. VERY COMMON

PS, IF a Black tank odor, the Flange rubber seal may be worn and bad.

[opnspaces]

All drains except the toilet need some kind of venting after the P trap to avoid a siphon effect draining the trap. Look under the sinks at the P trap and you should see a vertical T. The top of the T will either be connected to the vent pipe to the roof or terminate about a foot above the trap. If it terminates you can reach up and unscrew the AAV and see if air passes in both directions. The AAV is a one way valve letting air into the tank but not letting the air and stink back out of the tank. If you can pass air both directions replace the valve.

[StirCrazy]

Grit dog wrote:
^Bingo. Or black vs gray smell is typically totally discernible to all but the most oblivious sewer dumper. Lol

Does it happen all the time or only if traveling with partially to very full black tank?
Only had 3 “RVs” now but all of them were the same, both older and fairly new units. If black tank was fairly full and we’d travel a distance, like any sustained highway driving, the black tank odor would come into the camper.
Not the P traps or gray.
And no other odor issues.
Seal around bottom of toilet like mentioned recently could be it.
My solution was to dump what I hoped I could have dumped 100miles sooner, lol.

I am leaning towards the toilet seal myself. if its not hard I may just go for it, or at least check to see if it is all tight first haha..it looked like a brand new toiler when I bought it sticker still on it and everything ... I am trying to think about if it happens only when I have stuff in there and I think so. maybe I'll see how hard it is to change that seal and go from there. thats the only thing that makes sence to me.

[StirCrazy]

RLS7201 wrote:
If the Air Admittance Vent doesn't fix your issue. There is another possible reason for the stink inside your RV. When going down the road, the inside of the RV goes into a negative pressure, caused by the large flat area in the rear. This allows the pressure differential to induce a stink in the RV. I replace the caps on the roof vents with sanitary Ts, to put the tanks into the same pressure as the inside of our MH. Or you can purchase the rotating roof vents. Rotating roof vents.

Richard

I have to take another look but I have never seen an air atmittance valve for the bathroom or the kitchen sink for that matter.. my thinking has been that maybe the vent is plugged or not venting right, but the smell is only pulled into the bathroom not the rest of the camper where I would expect it if that was the issue

[StirCrazy]

MFL wrote:

enblethen wrote:
Water sucked out of drain traps
No water in drain traps
Vent under washroom sink stuck open, if equipped. air admittance style vent

I agree, it doesn't sound like the black tank could be the issue.

Easy to fill drain traps, including sinks and shower, when stopped. Does smell go away?

Jerry

the smell goes away if I don't fill them. but I do fill them all up before traveling and they still have water in them when I get to where Im going. once I am stopped the smell will go away with in say 15 to 20 min

[StirCrazy]

opnspaces wrote:
Yes probably an air admittance vent AKA cheater valve the is not longer a one-way valve. Available at Lowes or Home Depot for around $10

there all p traps. and why would that be on the black water system?

[StirCrazy]

enblethen wrote:
Water sucked out of drain traps
No water in drain traps
Vent under washroom sink stuck open, if equipped. air admittance style vent

all p traps still have water, that was my first thought..

I'll have to go look again I have never seen an atmittance valve in this camper.

Steve

[RLS7201]

If the Air Admittance Vent doesn't fix your issue. There is another possible reason for the stink inside your RV. When going down the road, the inside of the RV goes into a negative pressure, caused by the large flat area in the rear. This allows the pressure differential to induce a stink in the RV. I replace the caps on the roof vents with sanitary Ts, to put the tanks into the same pressure as the inside of our MH. Or you can purchase the rotating roof vents. Rotating roof vents.

Richard

[Grit_dog]

^Bingo. Or black vs gray smell is typically totally discernible to all but the most oblivious sewer dumper. Lol

Does it happen all the time or only if traveling with partially to very full black tank?
Only had 3 “RVs” now but all of them were the same, both older and fairly new units. If black tank was fairly full and we’d travel a distance, like any sustained highway driving, the black tank odor would come into the camper.
Not the P traps or gray.
And no other odor issues.
Seal around bottom of toilet like mentioned recently could be it.
My solution was to dump what I hoped I could have dumped 100miles sooner, lol.