Need Insight in Plumbing Issue

[Tamgary211]

Hi there,
Yes I am a relative newbie and I am a bit stumped with the plumbing in our '67 Caravel. From the looks of my Toilet's under belly it looks like the shower & sink water just stay in the piping instead of going to the black tand and when I open the cap to hook up to the sump and when I do all this nasty stuff dumps on me.When I open the valve in the bumper area I can see the ground thur looking in the toilet. How the heck is the toilet water going to the black tank when I can see straight to the ground? I have read the original manual and just don't get answers.

Can someone fill in the gaps here. Thanks a bunch

[repairsart]

Hi, '65 Caravel owner here. I just replaced the rotted plywood underneath the rear wall of the sink/shower/toilet area and am beginning to button everything up. Needless to say I had to remove the fiberglass insert and toilet and rest of the plumbing. My problem is the replacement size of the water line.
The grey water from sinks and shower stays in the drain pipes until you remove the cap from the line as you stated. The black water from the toilet stays in the holding tank (small) until you open the thetford valve which allows it to flow out. The grey water line runs to the thetford valve and connects to it below the black water valve area.
In my Caravel the toilet opening of the black tank on top and thetford valve opening on the bottom of the black water tank are offset by a few inches. You can close the thetford valve and the black water will not flow out but you could take the cap off the waste line and have the grey water run out. (boondocking). Hope this was helpful.

[Tamgary211]

Awww....Enlightenment!!

So the Grey water from the sink does stay in that drain pipe...But what keeps it from getting all over you when you take off the cap to drain the black water tank which is what is happening now.....Is our thelford valve stuck open?? I tested it and looking down the toilet with the thelford valve in the closed position I could not see the pavement.

Thanks so much for the information. I really want to take off the shower pan like you did, but after last week when some really icky water back flowed up the shower drain I am shuttering to think of what would have happened with no pan to contain it...

Joanie