Vent issue-help me understand this

tinstartrvlr wrote:
Evening everyone,

I seem to have an issue with the gray tank venting properly, and it only occurs while taking a shower.

There is a rotten stench that comes from a ceiling level kitchen cabinet, with a lesser smell coming from under the kitchen sink and from the bathroom vanity.

Roof vent is clear, the under sink vents seem okay; by that I mean I took them off and the diaphragms seems to be moving freely. I don't know how to tell if they are faulty however.

Don't believe the water heater is the source because I never have the smell unless showering, (hot water doesn't smell otherwise) and I use the shower daily. Diligent about flushing the water heater regularly.

No dry P traps, no break in the vent pipe that I can find; I have tried all the usual suggestions I have read here previously, but I certainly could have missed something.

So it was suggested to me by a neighbor that I leave the gray tank drain valve open, and voila, no smell.

Anyone know why leaving the gray valve open would eliminate the smell?

Where does your vent exit your RV? I would check and see if something maybe mud dobber, bird nest, has plugged the vent. The smell's would seam to come from the vacuum breaks. When you open the gray water dump valve you are "venting" the tank.
Let us know what you find.
Bill



.