Faulty Black Water Valve

For those not familiar with changing the knife valves, simply loosen the four screws holding the valve in place. Loosen each screw SLOWLY, one at a time. Do NOT remove the screws completely, just loosen them. As you do so, the valve will start to separate and the "fluid" will begin draining out. Have a pail or similar container under the drain to catch the fluid as it drains out. Empty as necessary, then repeat until tank is empty.

If the tank is empty, simply remove the four screws, separate the valve from the connection and remove. When reinstalling, ensure BOTH large O-rings are securely in their respective housing recesses before tightening.

Finally, as Jeff, found out..if one valve fails, it's a good idea to replace both...they're not that expensive and it'll save you the trouble of removing everything twice. While you have the valves off, run a hose inside the tanks in both directions to ensure clean and trouble free dumping for years to come....Dennis

Houston...We have re-established service! After many, many hours of "what-if's", probability analysis (not really) and many great suggestions by everyone here, we have an operational black water valve without having to notify the EPA or having to post incriminating video on Youtube (sorry everyone who asked for video) :thumbsup .

I was going to wait a couple days before attempting to resolve the situation but decided the long, slow rains today would be beneficial in helping to eliminate any evidence should there be any. So I moved the Bus outside (stored inside), strung out the garden hose, slipped on the newly purchased long rubber gloves, connected the portable tank...and took my last breath of fresh air. Since the discharge angles down immediately after the valve I decided to drill a hole in the discharge elbow in a position that would allow insertion of a long screwdriver to reach the gate blade. The hole was drilled at the diameter that I could later tap 1/4"NPT and install a pipe plug when done.

I inserted the screwdriver against the gate blade and pulled on the handle just to confirm the valve was stuck...but I could feel it move! I pulled the valve handle full open and could feel the screwdriver slide along the gate blade until it was fully open! Great - it's not stuck closed! Wait...nothing is coming out...pause...prod around with the inserted screwdriver...hear a few dribbles, then a little more...uh ho - realization that I may have dislodge whatever was plugging the discharge and it might just coming gushing. Quickly closed the valve then slowly cycled it back open. A few more dribbles, then finally a decent flow!

Fortunately there was only about 15 gallons in the tank so I didn't run the risk of over filling my portable tank. Did a major spray in the tank to dislodge more junk - I suspect its been building up there before I acquired the motorhome earlier this year. So I'll do some more cleaning on it over the next several days and probably replace the valve anyway.

Such a relief and nice to breathe fresh air! Thanks for the suggestions and the link!

This thread from a couple of days back may have the answer you need.

Brett - Since the stem won't come out of the endcap I suspect part of the gate may still be attached to it. I'm considering using a Dremel cut-off blade to just remove the stem cap. If I can get the cap off and the stem out then I'll try the larger bolt you suggested.

Of all things, I purchased a replacement gray water valve last week because it was leaking - should have change the black while I was at it!

Have you tried screwing the stem back on the blade?

If the blade is stripped, try to find just a slightly larger thread-- bolt or all thread.

Mr. Jeff wrote:
Well yuk! After a long weekend with four kids needless to say our tanks need to be emptied. so off I go to the local dump station, get all hooked up and pull the black tank valve and....nothing. Not even a dribble. I have now determined that the T-handle stem has separated from the valve gate blade.

So now the BIG question - how do I get this valve open, while connected to a dump line, without becoming a scene from the movie RV? And yes, I will absolutely change it once the tank is empty!

Anybody want to help? :h

OK
I have never actually takem one apart but I think the rod is factory wedged into the gate valve?If so heres an idea.Chip away at the black plastic area where the metal pull rod comes up till u can get the rod out.Wrap tape around the the rod and drive it back in like a wedge into the hole it comes out of and then see if it hold,s good enough to now be able to pull the gate valve open.
Ok if its threaded like wolf says then maybe put tape on the threads and see if it will hold at least enought to get it dumped