Recently we went to Virginia . I know what you're thinking.... why would anyone want to go up to cold country from Florida ? Well to make things simple I was over ruled . So my wife , son , and two g...
I've had the loose vent cap under the sink as well and just had to tighten it back down. The big question would be what you thought you could identify from the bad smell, human waste or rotten food in the grey tank? In your toilet area, do you leave a 1/4" of water in your bowl? It helps make a seal.
another troubleshooting thing you can do is remove the vent cover on the roof and chase the vent tube to the black tank to make sure it isn't plugged with debris or a mud nest.