[BigBoy2U]

OK thanks, I can't seem to smell it in the basement. I checked the cold air return and even with the fantastic fan on and I can feel air coming in from the basement (nothing beats that kind of dirty musty smell) I can not smell it. But if I leave the bathroom window closed and turn on the bathroom exhaust fan or the fantastic fan it stinks. But only in hot weather...LOL

I am pretty sure I need to pull the toilet and check the O ring. I just can't believe a poor seal at that point would make that much smell.

The odd part was when I was on the roof the roof vent had no odor at all. It was in the high 80's that day and the bathroom was stinking but the roof vent had no smell.

I even emptied the black tank thinking the pipe might have slipped down and still no smell.

On my last trailer the roof vent always smelled like a sewage plant.