Sewer vent smell - need advice

Old-Biscuit wrote:

mrkoje wrote:
I've had the black tank pretty darn close to full and nothing out of the ordinary. I'm not sure I'm 100% on what you mean by a burp. I'm taking it as gases escaping from the toilet opening when flushing. When I flush it does get smelly but it doesn't make an audible sound!

YES............tank venting up thru toilet because vent line (if slipped down into tank) would be blocked and as you flushed the air/gases in black tank would have to come up out of toilet.

It does make an audible sound when that happens......and can spray back.

So it sounds like a 'craftsmanship' install......vent line cut to short. Should be at or above roof line and sealed from 'attic' area of roof.

Well I haven't had any "spray back!" Hopefully never do though it's possible with some the DWs cooking lately!

Rollnhome wrote:
Stick a steel measuring tope down the vent. Unless their is a bend it should go to the bottom of the tank. Take a measurement. When pulling the tape out you should be able to catch the bottom of the vent pipe. That will give you another measurement. From there you will know if the pipe is on or close to bottom of tank. If not on bottom it should be sealed at top of tank, try to gently turn or lift up.it should not move. If it doesn't move I'd add a coupling or 360 vent. If it moves....go get a beer it's going to be a long day.

I'm going to do this. Really I'm just hoping who ever was in charge of installing the pipe was lazy and cut it too short. At least that way I can make quick work of extending it out. I didn't want to remove the rest of the vent cover today because I'm going to need one of those 360 covers to replace it. Once I take the rest of the old cover off I should be able to see a little bit better on whats going on in there.

myredracer wrote:
It also could be a faulty air admittance valve for the grey tank. It will be inside the vanity cabinet. The smell from a grey tank can be almost as bad as a black tank. The valves are one way and are not supposed to let gases/odors back into your RV.

We have to replace the AAV for our galley tank which is under the kitchen sink. It's only months old. We're far away from home on vacation and DW kept complaining about a smell. I wouldn't have suspected a faulty AAV that is so new. One wiff next to it confirmed it's not working...

They just screw onto the ABS pipe and don't cost much.

Though that is a possibility I've pretty much ruled that out so far. Reason is that the smell is faint under the vanity in the bathroom yet it is strongest around the base of the toilet. Once you open the toilet you better run - I wish that smell upon no one ever. Also, after I did some investigating on the roof it is kind of obvious that something jacked up is going on with the vent pipe. Because it looks so jacked up I'm reasoning that is the most likely candidate on why it's not venting properly.

mobeewan wrote:
How about using an inspection camera to put down the toilet into the black tank to see if the pipe has slipped down?

I could go this route but being I don't have an investigation camera immediately accessible I'll try the tape measure method first. Though it is a good reason to get another tool!


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Thanks all for the replies. Some good ideas I didn't think of and confirmation of what I kind of thought might be the issue.

I'll let you know how it goes. I'm going to order the 360 vent tomorrow.