A few weeks ago when I was at Land Yacht Harbor in Melbourne, there was an older RV service guy working out on the road on someone's AS trailer waste water valves.
A subject I have always been interested in knowing more about in case I ever have problems, so I couldn't resist having a chat with him.
He was a real old timer in the profession and a very decent guy who was quite willing to share some of his experience with me - I learned a couple of things .......
(1) About accessing the valves. I had always thought you had to cut an access panel. He said you can, and many people do, but what he often did - and was doing in this case, was to loosen bolts on the metal pan that covers the tanks and valves on one side of the trailer and at the middle, leaving the bolts on the other side in place.
This allows the side of the pan where the pan to drop down to the ground giving enough room to access the valves. Leaving the other side still attached makes it much easier to lift the pan back up with everything in alignment to re-secure it I imagine.
In this case, he was replacing both the black and gray waste valves for the owner, and was doing it just this way. - took him maybe a couple of hors total.
(2) I mentioned my concern about one day having a valve rod pull out and how to deal with it, asking him how he dealt with that, especially if it was with a full black tank, and if maybe he had to resort to first getting the thank pumped out via the toilet.
He had the old black valve out and used it to show me what he said that he encountered most and how he dealt with it.
This is a bit hard to explain, and I wasn't entirely sure I understood but I'll try!
He showed me how the rod fits into the blade. I had always thought it would be either threaded into the blade or moulded into the blade, but it is not.
Instead,the operating rod has a little groove machined maybe 3/8"from the end forming a little knob at the blade end of the rod.
This fits into a little "pocket" in the blade, so allowing the rod to move the blade back and forth. The sides of the valve assembly keep the rod in place
So I asked what happens when it fails, does the plastic on the blade break allowing the rod to pull free?
I was surprised when he told me no. He said what he has always found is that the rod corrodes to the point that it can just pull out. I expressed surprise as it looks like a stainless rod. He agreed, but still told me that is what he finds.
But then the interesting part - I asked him what does he do then to empty the black tank.
He said he has always found that if he grinds away the corroded edges of the rod that had failed, pushes it back into the assembly and rotates ninety degrees it will catch in the blade and he can pull it open.
I found this a bit hard to understand, but the guy sures sounded as though he spoke from many years of experience!
I can only assume that the rod must only corrode where it is in contact with the plastic slide so that when he rotates it ninety degrees he brings a fresh surface of the rod to bear and again grab the slide
Not sure what good it does for him to clean up the rod the way he described by grinding the corroded sections - maybe it just makes it easier to put the rod back in and to easilydo his ninety degree rotation?
Probably something I would at least try if i ever had the problem, I appreciated his taking the time to talk with me and certainly thanked him!
In Barnacle Bill's excellent write up and pictures above, you can see exactly the configuration of the end of the operating rod I tried to describe.
In his case though it sounds as though the actual plastic of the blade had in fact broken away, unlike the experience that my "mentor" told me that he encountered many times!
When I asked, he told me he had not seen a broken plastic blade so far in his experience.
For what it may be worth if you should be so unfortunate!
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.