Doug Dotson wrote:
I guess you meant Joker Valve.

No...I meant downstream of the whole toilet.

The only thing that could do that is the vented loops.

Nope...they're the least likely candidate...worst case in a vented loop
is, it becomes just a loop, unvented.

Likely possibilities are sea water calcium carbonate buildup in the head
discharge line (did you take a look inside when you had it off to
rebuild the toilet?) or a partial clog created by something that
shouldn't have been flushed--which can be in the line, or in the L/S if
you've flushed solids or TP without running it...or a barnacle may have
attached itself to the discharge thru-hull, preventing the L/S from
discharging.

Whatever it is, look downstream of the whole toilet...'cuz backup into
the bowl can only mean one thing: something downstream of the toilet is
creating backpressure that won't allow the flush to pass. The longer it
takes for the backup to appear in the bowl, the further downstream of
the toilet it's likely to be.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://69.20.93.241/store/customer/p...40&cat=&page=1