Has anyone had a clogged plumbing roof vent pipe?

I had the same sewer smell problem that came and went frequently for about a year. I replaced the air valve as shown in earlier posts with a NEW one, but that didn't fix it. However, wrapping saran wrap around the air valve temporarily using a rubber band did eliminate the smells! No issues with draining the tank. So now a zip tie holds the saran wrap around the valve. Might work for you too?

Jim4929 wrote:
Thanks for the answers so far. Here are the answers to questions posed so far.

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5. Also, a telltale sign that a vent is blocked is that the appropriate tank drains slowly or is struggling to drain when dumping. Do you have this problem?

Wife uses the kitchen sink the most and has not complained about slowing running sinks.

Thanks for all the help so far. Please keep throwing stuff against the wall....something might stick.

Not the sink, but the grey tank itself. If it tends to gurgle or is slow draining, the vent may be clogged or, if it's the under-sink variety, defective. If you have a clear hose connector, and see air trying to head back upstream, that's a sure sign that the vent's not working as it should.

Lyle

Answer is in post 2

This has worked for me in the past. Ask the wife to stay in the rig by the sink just in case. You go up on the roof with a hose and take caps off vent pipe then stick hose down the vent turn on all the way. If there is a blockage the water will blow it back into the tank. Only thing to be careful of is that it doesn't come out someplace in the coach. That's where the wife comes in. Leave it run for a few minutes then see what you got.

I've had two RV's that had the black ABS pipe installed too high at the roof vent. Then when they installed the rain cap it plugged the pipe off. Sure made a huge difference to how well the tanks emptied when I fixed them.

Any chance that there is a dead critter lurking back there somewhere?

Thanks for the answers so far. Here are the answers to questions posed so far.

1.It could also be something like this that has failed, and needs to be replaced.

Under Sink Vent

I have one of those under the half bath sink that goes to the same vint pipe....how would I be able to tell if it has failed?

2 Is the smell a "sewer" smell or an "ammonia" smell? Different fixes for each.

Mostly sewer with a slint tinge of ammonia. Since the oder started Thursday, there has been no decrease in refrigerator opeations.

3 First of all I would check the pilot lights/stove knobs on the stove. I had one bumped on and thought it was the gray tank smelling.

Checked that out upon your recommendation and all appears normal.

4 Are all your p-traps filled with water? That water can evaporate and allow smells up thru the drain.

If all that checks out ok. It could just be a stinky gray tank.

The oder is not coming out of the sink drain as I would expect if the p-trap was empty. (last night I closed the drain and filled the sink with water in case this was the case...again no joy)

Did a complete back flush of the gray tank this morning...again no joy

5. Also, a telltale sign that a vent is blocked is that the appropriate tank drains slowly or is struggling to drain when dumping. Do you have this problem?

Wife uses the kitchen sink the most and has not complained about slowing running sinks.

Thanks for all the help so far. Please keep throwing stuff against the wall....something might stick.

Check that vent adapter under the sink, I recently changed ours. You can get them at Lowes, Home Depot or any plumbing store. :)

rockhillmanor wrote:
First of all I would check the pilot lights/stove knobs on the stove. I had one bumped on and thought it was the gray tank smelling. Turned out to be propane coming out from a stove knob that got bumped to the on position and the propane was finding its lowest spot behind the stove and into the sink.

.

X2 discovered mine at 2 am, had to open the windows and take a nice midnight stroll.

Before you go crazy and start taking the inside apart, maybe go on the roof and pop off the cap to the vent and see if you can see if it is blocked from the top. Sometimes insects and critters can create a blockage on at the top of the vent. You could also push a fish tape down the vent from the top to see if you can feel a blockage that way as well.
Also, a telltale sign that a vent is blocked is that the appropriate tank drains slowly or is struggling to drain when dumping. Do you have this problem?

Edit: Wow, take a couple minutes to type a response and get beat to it by several others. Man, I have to learn to type faster.