tkcas01 wrote:
newman fulltimer wrote:
Look under the sink your vacuum breaker might be bad.Does the toilet hold water in it?
This it often the cause of such odors, and in fact coming from the grey tank. There is typically an "auto vent" near the sink, the lav(s) and washer area. Even if your rig is plumbed for a washer and does not have one, it may still have an auto vent in place for it.
They do go bad over time and let air from the tank back into the RV. You can get them at any home improvement retailer.
Is that the part that's on top of the pipe?