Odor from kitchen sink cabinet on 3850

[cardinalrancher]

Last fall had odor coming from kitchen sink cabinet. Did not have full hookup. The odor went away after draining tanks. Is it possible the tank vents on top of unit were plugged?

[mcwhirtj]

That might cause sewer gas to vent back through the p-trap into sink, but I can't see how it would vent in the cabinet space. Odd.

[Flybob]

Check under the sink for a vacuum breaker valve like photo below. They are notorious for sticking open allowing tank gases to escape. You can try tapping it, but usually best to replace it. Can be purchased ant some big box stores.

[cardinalrancher]

Thanks guys for your help. Will check that vacuum valve. I can see how that would stick and allow gases to escape.
Thanks again!

[mcwhirtj]

Originally Posted by Flybob

Check under the sink for a vacuum breaker valve...

And I learned something today! I was not aware of such a thing. Now I am! Thanks for your reply - seems like this is most likely the OP's problem.

[fenderbender]

Originally Posted by mcwhirtj

And I learned something today! I was not aware of such a thing. Now I am! Thanks for your reply - seems like this is most likely the OP's problem.

There's one under the bathroom sink too. I replaced both at the same time and solved that problem. Bought them at home depot

[CedarCreekWoody]

It is called a air admittance valve, intended to let air in but not out. It is not unusual for one to malfunction. A temporary fix, until you can replace, is to cover with a plastic bag and seal with tape. That will stop odor but sink may drain slowly or pull the water out of the trap (and let odor in that way).

[rlh1957]

If it has been sitting and water in the p-trap evaporates enough, smells and gases from grey tank could come up in the camper, especially when you turn on or have an vent fan on. Every so often go in and pour a half quart of water down each drain in shower, bath sink, kitchen sinks. This keeps the water seal in place. Unless you will be draining the grey tanks. I pour the grey tank treatment in so the tank smell is killed and also some of that stays in p-trap to keep that water from going sour as well.

[Larry-NC]

Originally Posted by CedarCreekWoody

It is called a air admittance valve, intended to let air in but not out. It is not unusual for one to malfunction. A temporary fix, until you can replace, is to cover with a plastic bag and seal with tape. That will stop odor but sink may drain slowly or pull the water out of the trap (and let odor in that way).

Or a plastic bag and a rubber band.

Larry

[Wolverine 1945]

Originally Posted by cardinalrancher

Thanks guys for your help. Will check that vacuum valve. I can see how that would stick and allow gases to escape.
Thanks again!

I would try removing them and cleaning them before I would replace them !!!

[bill and theresa]

they are less than $5 at THD. I just replaced mine.

[jacknife]

Just exactly where is the valve ? It all looks like pipe which is the valve ?

[CedarCreekWoody]

On the top of the black pipe on the right. It screws on.

[jacknife]

Got it thanks !