Hi, I'm new here but I thought this information might be helpful to someone else who may owner or consider buying a Jayco 165 Sport.
I recently bought a 2004 model that is in good shape and is pretty much stock. I was surprised to discover that the shower drains directly down into the black water tank, which is only 11 gallons. Meanwhile, the gray tank, which is twice as big only receives water from the sink. That's a terrible design flaw, and a sign of lazy planning and manufacturing.
So last night I re-plumbed it to the gray tank. It took about an hour and cost about $15 in parts.
Here's a shopping list (all pipe is 1 1/2" ABS drain pipe and fittings):
1 - slip-fit drain cap
1 - Vent elbow (that's the tight angle 90 degree bend)
2 - 90 degree elbows
1 - 45 degree street elbow
1 - long sweep sanitary tee (looks like this:
http://www.homedepot.com/catalog/pro...9c4bf_1000.jpg)
1 - 10' abs pipe
1 - black abs glue
I recommend pipe cutters, I actually used sprinkler pipe cutters because cutting the drain between the trailer floor and the black tank happens in a really tight area and I could just barely get the sprinkler pipe cutters around the 1 1/2" pipe.
I routed the new line along the rear of the black tank, in the space between the tank and the floor and attached it directly to the gray water line. I couldn't see a need to take the line directly to the gray tank itself.
Note that you'll need a second person to help push in the pipe that goes along the back of the tank. Everything else is a one person job.
Here are some photos of my install:
http://www.jaycoowners.com/attachmen...e42dbab906.jpg
http://www.jaycoowners.com/attachmen...7c75933703.jpg
I hope this helps someone else who may find themselves baffled by Jayco's incredibly lazy decision to drain the shower line into the tiny black tank.