Black tank overhaul: Thetford to Valterra tank fitting conversion/ plastic weld

[tweezerlips]

As it turns out, the original white ABS Thetford mounting flange at bottom of black tank was a slip fit with hose clamp. The tank is Polyethylene just has a green tint to it. I used a RotoZip to cut the four corners off of the mounting flange so that I could spin (still thought it was threaded in) the flange out of the tank due to the plywood surrounding the flange was cut tight around the flange. Once I cut the four corners I could feel around above the flange and discovered the hose clamp. Used the RotoZip again to cut the rusted screw and pulled out the flange.

I have ordered a new Valterra valve, valve flange and collector. Just hope the collector aligns up the 2" gray waste line once installed. Not such a difficult project but it does require a bit of research and this forum was very valuable information to have.

[VintageRV]

Wonderful! Great job sticking with it.

[jack9443]

i HAVE a 1977 Argosy center bath 28' my dump vale comes stright down and with the thetford to valtera adapter and a 90 i am only 9 " off the ground, below the campground dump connection and we all know it don't run up hill
I am trying to change out all the thetford also

[jack9443]

used thetford valve to black tank and glued and 3/4 "screws to attach a 3"90 with a 2" heal turned towards front of trailer then a street 90 and 2" of 3" pipe to connect a valterra bayonet
then connected a 2" valterra blade valve to the heal plumbed to gray tank now instead of straight down with an adapter its now turned out and gray tank dump is easy to get to it was under on frame works great