Black tank valve

richard5933 · April 13, 2018, 01:09:33 PM

This is the valve on our combined gray/black tank. On the small side (2"), but generally it works well. The green crud is from condensation - there is no leaking around the outside of the valve.

Problem is that the valve has started to let liquid seep past it and out the discharge hose. Not much, maybe a few drops a day. But once the tank is full I'm sure it will be worse. I've got a cap on it right now to catch whatever seeps past the valve, but that's not a long-term solution since it makes for pretty messy dumping.

My first thought was to remove the large cap and see if it can be cleaned and maybe have new seals installed. However, I can't get the top to turn and I'm afraid to try too hard as it looks pretty easy to damage the bulkhead connection to the tank.

Any one have thoughts about plan of action?

Right now my leading plan is to install a modern gate valve downstream. The piece that looks like black iron pipe coming from the bronze valve is really rubber hose. I was thinking of removing a few inches and installing a Valterra 2". Ultimately I want to have a new tank made with spin-on fittings, but that's not in the budget now.

Thoughts? Suggestions?

Dave5Cs · April 13, 2018, 04:53:00 PM

Just an idea, I would go somewhere and dump the tanks and wash them out from both ends. Then take it to where ever you work on it and take it all apart maybe get some numbers off it and or figure out where you can buy new seals etc and rebuild it. Why temporary it. You will be on the road if and when it fails with no recourse. Just sayin.

richard5933 · April 13, 2018, 06:04:56 PM

Quote from: Dave5Cs on April 13, 2018, 04:53:00 PM
Just an idea, I would go somewhere and dump the tanks and wash them out from both ends. Then take it to where ever you work on it and take it all apart maybe get some numbers off it and or figure out where you can buy new seals etc and rebuild it. Why temporary it. You will be on the road if and when it fails with no recourse. Just sayin.

Black tank is actually empty right now other than a few gallons of RV antifreeze. I have full access to the valve. Problem is that it just doesn't want to budge. The number on the valve is Stockham 125S. Can't find much info on it online, so I'm guessing it's an old style valve.

luvrbus · April 13, 2018, 06:57:35 PM

No they are still around they are called quick opening gate valves I have some Morrison

richard5933 · April 13, 2018, 07:11:22 PM

Quote from: luvrbus on April 13, 2018, 06:57:35 PM
No they are still around they are called quick opening gate valves I have some Morrison

Any suggestions on getting the top opened? Am I correct in assuming that once it's opened I have a decent chance of getting it cleaning and working again? I have no clue what I'll find inside or if there is anything rebuild-able in there. My thought is that there is probably just a bit of gunk keeping it from closing properly. Another thought - if I remove the end plug on the discharge hose I can get a hose inside the valve. Any possible benefit to getting a nozzle in there to flush things out?

chessie4905 · April 13, 2018, 07:26:57 PM

personally, I'd remove that valve and assoicater parts, and replace with conventional manual valve.

eagle19952 · April 13, 2018, 08:05:19 PM

i have no words.
I have an acronym.
K.I.S.S.

Iceni John · April 13, 2018, 08:20:14 PM

Some folk have even used plastic ball valves instead of the usual Valterra-style RV blade valves. Why not?

John

Brassman · April 13, 2018, 11:44:58 PM

If I was going to rework the valve I would remove it. It's a top dollar quick action gate valve, as has been mentioned. But if it's a leaker, what do you do?

richard5933 · April 14, 2018, 05:20:15 AM

Changing out the main valve would require removing the black tank. Even with the tank out and the valve removed I could not simply swap it for a modern discharge valve, since the flange for the tank only has a 2" opening. Then I'd be at the point of removing and replacing the tank with a new one. That's just not in the budget right now. I've gone as far as the cash allows this year doing what's already been done, at least if I'm going to have a buffer for the inevitable problems on the road. For now I'm looking for something that will function and allow for relatively easy dumping until the tank can be replaced at some point in the fall or next spring.

I see two viable and affordable solutions right now:

1. Add another valve downstream.

2. Figure out how to open the bronze valve without damaging the tank and/or flange. (I've never opened one and haven't been able to find diagrams/photos of the process so I don't know how well this would work or if it would help.)

And one possibility if the parts exist:

3. Remove the current valve & flange and replace with a modern setup. This would only be possible IF there exist a way to add a bolt-in flange to an existing tank without having access to the inside of the tank. (There is no way possible to reach to the back side of the flange location other than through the flange itself.)

chessie4905 · April 14, 2018, 06:16:36 AM

how close is the toilet flange to that end of tank? If it's close enough, you can remowe tank and, after cleaning, reach down and remove nut holding valve. enlarge hole to accept larger standard valve with flange nut and gaskets assys and install. Reinstall tank. If toilet flange hole is too far away, cut hole in top of tank above valve. Patch hole with same plastic material, gasket and several ss sheet metal screws. Dont overtighten and strip screws.

olebusman · April 14, 2018, 07:39:29 AM

How about taking the old flange out of the tank and spinweld another flange, of the 3" size, for a slide valve. Spin weld with a router. olebusman

richard5933 · April 14, 2018, 08:31:31 AM

Quote from: olebusman on April 14, 2018, 07:39:29 AM
How about taking the old flange out of the tank and spinweld another flange, of the 3" size, for a slide valve. Spin weld with a router. olebusman

Have you ever done this? How do you think it will go over the holes from the bronze flange? If you look at the photo, the mounting holes are outside the 2" actual opening size. Not sure if there will be enough overlap from the lip of the spinweld flange to cover the old mounting holes.

olebusman · April 14, 2018, 03:10:22 PM

I have not. I made my tanks out of abs plastic therefore easy solvent weld. Google spin weld fittings.

kyle4501 · April 14, 2018, 05:01:18 PM

I see nothing wrong with adding a valve down stream for the short term.

For the long term, if you can't service the existing valve, replacing it with a PVC ball valve would be my first choice.

If the existing valve can't be serviced, you may as well sacrifice it to save the hassle of changing out the tank bulkhead.

Sometimes, simply using a cut off wheel to cut into the hub so a couple of pry-bars can be used to expand the hub & make it easier to turn.
I have also had good luck using a grinder to remove as much of the old valve as possible without damaging the threads on the parts I wish to keep. Then it is easier to remove.

Careful application of concentrated heat has benefits. Improper application of heat can result in exponential negative results, so use heat with caution.