Unexplained Odors

Check the roof vents, and the air admittance valves, which are normally under the sinks. Also the battery fluid levels.

It is smells like rotten-eggs i would check the battery fluid levels... Your older trailer may only have a single mode converter/charger in it and it is well known here that batteries will boil out their fluids being on the 13.6VDC charger for long lengths of item...

Hopefully if your are low and haven't been in this condition you can just add distilled water and be ok...

When mine did this I ended with a shorted cell after I thought i caught mine quick enough and the battery failed...

A fully charged battery sitting with no load should read 12.6-7VDC across the terminals. With a shorted cell mine read 5.6VDC at the terminals (GAME OVER)

Roy Ken

you should treat your gray tank like you do to the black water tank.

Your tanks are all vented to the roof. You should have one vent for each tank and each sink should have it's own 'cheater' valve. (Your shower or bathtub is most likely vented to the roof).

I've never had this problem, but check your roof vents to make sure hornets or mud daubers have not built a nest inside your vent on the roof. Easiest way to find out is to simply remove the vent end and stick a garden hose down the pipe. If you have a garden hose with the end cut off, it will work a bit easier.