The black knife valve on my 2004 Holiday Rambler Vacationer 36WDD does not seal tightly, and juice seeps down in the drain. It is a pull/push cable actuated unit and is way back in the wet bay out of sight. Does anybody know how it can be accessed for service or replacement? I have tried numerous methods to clean it from above through the toilet without success. I currently have a short section of old garden hose connected to the drain cap, that is equipped with a 3/4" connector, and poking down through the floor hatch. Otherwise, it will fill the drain with liquid between dumps. I had that unpleasant surprise once. I used to put 5 gals. of water in it after dumping but now keep it empty except to travel and camp.

you may have to get at it from the under belly, worst design everi suggest thishttps://www.amazon.com/gp/product/B000BGHYJS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1twist on valve, put this where you have the cap no more surprises no more drips

Its not the vavle itself, it is the cable that is bad.

Once you determine which brand it is and have the replacement in hand, the job is pretty easy. Messy but easy. Remove the belly cover to expose the valves. Remove the 4 acrews and nuts. Place a bucket under the valve. Gently pull things apart. Lift out the blade and gaskets. Liberally grease the new parts with plumbers grease. Reinstal in the reverse order. If your careful it should take no more than about an hour.

I had a leak in mine, which has the two tank pipes, each with valve joining together. No flexibility at all and the screw on valves have rims that need a quarter inch of space to come out. I bought new valves bit postponed installing because I will have to cut a section of pipe out and put in a rubber joint. Meanwhile, someone here suggested putting a little vegetable oil in each tank - would you believe, that stopped the leak!

Thanks for all the comments. That Valterra valve looks like the answer. I had told my wife before that was posted that I thought I could make something similar but not that cheap. I looked under the bottom of my wet bay and there is no access panel there. When it gets warmer I will drop the control panel in the wet bay to see if the cable and valve can be reached but from what I can see under it that will be a lengthy reach at best. The add-on valve could be a long term solution to the problem and easy to keep clean, too. You can watch the video but not on Google Chrome. It is very educational about valves, not just the add-on part.

Replacing black tank knife valve Holiday Rambler Vacationer

13 Replies

Vacationer04
Explorer
Mar 11, 2019
I used one of those Valterra valves with great success, from 2016 until now. I noticed today, that what must be the anti-freeze from my black tank has backed up to the point, it is now seeping into the wet bay along with whatever else didn't get flushed out before winterizing dripping through the screw-in floor plug onto my driveway. I need to replace the seal in the valve or the valve itself. How can I access the valve? It is enclosed in a compartment, with no panels inside or outside that are visible. From what I can see, removing the wet bay control panel is not feasible, because of the dump valve cables being fed through it. HELP!
Huntindog
Explorer
Dec 25, 2016
MrWizard wrote:
You assume he will camp in freezing weather

He said nothing about what weather, only that he got splashed when removed the cap to attach the hose

If he empties the tank before cold weather can freeze anything in the tube
He's good to go
All true. But sometimes you can get caught by surprise with colder than expected temps.
It happened to me several times. With my last TT which did NOT have enclosed/heated valves, it prevented me from dumping when I really needed to.
My present TT WITH heated enclosed valves has never been a problem under those conditions.

Just something to consider.
MrWizard
Moderator
Dec 25, 2016
You assume he will camp in freezing weather

He said nothing about what weather, only that he got splashed when removed the cap to attach the hose

If he empties the tank before cold weather can freeze anything in the tube
He's good to go
Dave_H_M
Explorer II
Dec 25, 2016
taking that shortcut will get you in trouble just like the hunting dog says if it freezes up outside.
shepfly
Explorer
Dec 23, 2016
My two cable operated valves were totally enclosed on Ti fifth wheeler with heat so I built a small frame for just the valve area, so that access was as easy as removing a dozen or so screws. After more problems with the cable operated valves I replaced them with two Drain master electric operated ones, one of my best upgrades. Money well spent! Dave
westend
Explorer
Dec 22, 2016
I'm planning to add a wet bay to my old Starcraft. The whole bay will be heated for Winter use. The valves will be located right at the edge of the trailer for easy access and maintenance.
Huntindog
Explorer
Dec 22, 2016
One point to be aware of: The valves located in the underbelly are usually there for a reason. That area is often heated to an extent. This makes dumping is freezing weather possible.
Relocating the valve outside as is being suggested will do away with that capability... It can be a solution for those that do not use their TTs in freezing conditions though.
ernie1
Explorer
Dec 22, 2016
Vacationer 04,
I had the same setup you have in my rv and they were cable operated and the valves were located in a very difficult to reach area under the vehicle. After years of fighting with the valves, I relocated them to an accessible area at the outer edge of my vehicle and eliminated the cables, which I've decided were really not the source of my problems with the valves. What the problem was, was the lack of access to the valves for periodic maintenance like cleaning the sealing surfaces and lubricating the valves. Made the modification two years ago and am glad I did and wished I'd done it sooner. My latest mod is the addition of an electrically operated valve for the gray water line and I love it. Might do the same for the black water valve also.
Vacationer04
Explorer
Dec 22, 2016
Thanks for all the comments. That Valterra valve looks like the answer. I had told my wife before that was posted that I thought I could make something similar but not that cheap. I looked under the bottom of my wet bay and there is no access panel there. When it gets warmer I will drop the control panel in the wet bay to see if the cable and valve can be reached but from what I can see under it that will be a lengthy reach at best. The add-on valve could be a long term solution to the problem and easy to keep clean, too. You can watch the video but not on Google Chrome. It is very educational about valves, not just the add-on part.
Harvey51
Explorer
Dec 21, 2016
I had a leak in mine, which has the two tank pipes, each with valve joining together. No flexibility at all and the screw on valves have rims that need a quarter inch of space to come out. I bought new valves bit postponed installing because I will have to cut a section of pipe out and put in a rubber joint. Meanwhile, someone here suggested putting a little vegetable oil in each tank - would you believe, that stopped the leak!