Hi All, We have a 1998 diesel pusher that we just bought. There is a sour smell inside the RV that hasn't gotten worse or better over the past couple of weeks. We installed a new fan thing on the black tank vent on the roof. (It looks like something from the Jetsons and it's supposed to whisk away all smells from that tank.) That didn't make any difference at all. The smell doesn't seem like sewage, it's just sour and unpleasant. We empty our tanks regularly and we have started using an enzyme pack in the black tank. Is there something that I can try and put down the kitchen sink or something to see if that would help? Should we put another thing on the other roof vents? Any ideas?