Black Tank valve leaks need advice.

Xvatorguy

Advanced Member
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Dec 3, 2017
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34
Recently took delivery on 2021 Isata 3 , figured it was time to un winterize it in case we can find somewhere to go.
When I unscrewed the drain cap I thought it unusual that a couple gallons of Rv antifreeze drained out. I wanted to test out the holding tanks to be sure of no leaks . Grey talk holds fine , of course it’s the black. So now on my brand new Isata if I use it I can leave a full pipe of sewage when I take the cap off prior to opening the valve.
I am looking for suggestions to solve this I have flushed a couple tanks of fresh water with same results.
 
Initial thought, can you reach the valve blade? You may have a piece of construction debris in the valve seat. Just rinsing may not be enough to dislodge it. Next thing I would do is disassemble the valve to check for damage. You're lucky in that it's all still clean. :rolleyes:
 
That is an unfortunate scenario. We just got a new 5th wheel back at the end of November, and we had the same problem. Lucky for us, it was the gray and not the black. But, the process to fix will be the same. We figured, if we have someone fix it for us (mobile tech 45 minutes away) or bring it to the dealership (4 hours away) the time, and diesel, etc just isnt worth it. So we bought a new valve on Amazon for like $14. Not sure the cost for the black valve as it is larger diameter pipe. With the tank empty (if it has been used, I would really flush it good if possible), remove the 4 bolts on the valve, Separate the pipes from the valve, and pull it out. Then separate the pipes, slide in the new one, and install the 4 bolts and done. It is literally a 10 minute job. Be mindful you dont over tighten the bolts. But other than that very straight forward and simple to do. Its frustrating to have to do it on a new unit, but it just seemed like something that was not worth the trouble to have it fixed, and I just did it myself. Your other option, remove the current valve, give it a clean, lube it, and put it back in. Possible one of the rubber washers didnt seal right.
 
You may know this, but the actual valves are on the passenger side of the RV opposite the drain handles. If you look under the passenger side, can you see if there are any issues where the cable joins the valve? Have someone operate the valve handle and see if you spot any issues. My bet is also on construction debris keeping the valve partially open. If you open the toilet and use a flashlight, not sure if you can see the seal? One of the unfortunate things on the Isata 3 is the extremely long cables needed to reach the actual valves.
 
I added a valve on the end of the exit pipe, and a small clear piece on other side. I don’t open till hocked up to dump. Sometimes a piece of toilet paper can prevent closing. I also move valves open and close while rinsing to prevent any debris getting stuck.
 
While those valves that turn onto the end of the sewer port work, you really should fix it correctly in case you ever want to dump just the grey and not the black. You've been given some good advice on how to do so.

Another thing to check... there have been many, many reports of the cables that actuate the valve having issues. Many are routed improperly and bind to the point it doesn't close the valve.

If you have cables to the valves, check them too.

It should be under warranty and you shouldn't have to buy or fix anything.
 
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I had black tank valve problems a while back. Replaced with electric valve. Much better
 
Ya really need a good valve at the black and grey tank drains. An additional valve where they both exit to the sewer is an OK backup but you need to close the grey valve to avoid contamination with black stuff.

Silicone spray on the valve blades frequently is all ya need to restore their sealing and operation. If not replace the entire valve. I think I've done it twice on my black tank, never on the grey. Yeah, it's a poopy job.

-- Chuck
 
Not unusual...if its brand new, maybe the valve did not seat properly. I'd open and close and test with fresh water for a bit. See if you can clear the debris, or as others have said look at how the cable is routed for the valve. Make sure its not kinked or has a sharp bend.
 

Hard to answer your question without knowing the location of your black tank relative the sewer drain. As far as I can tell, what you're dealing with is a common design issue not something that can be repaired. The solution suggested above is simple. That device is sometimes called a line end shutoff or something like that. Same thing happened to me with a new fifth wheel. There's a pipe run of about 15 feet from the tank to the drain point (where I attach the drain hose). The valve for the tank is close to the tank, So that 15 feet of pipe may contain several gallons of waste water even with the tank valve closed. So when you undo the drain cap, you get a messy bath. For me it was grey water that came gushing out. A little research on this site led me to that line end shutoff valve which attaches where you attach the sewer hose and has a bayonet connection to attach your sewer hose to. I mounted mine semi-permanently using gorilla tape. When I need to drain my tanks I remove the cap, hook the hose to the added valve and open it. Any waste water in the pipe goes out. I then drain the tanks as usual. When I'm done I hope to remember to close the drain end valve and replace the drain cover.
:signhavefun:
 
How to spray silicone onto both sides of drain valve, even if closed

Ya really need a good valve at the black and grey tank drains. An additional valve where they both exit to the sewer is an OK backup but you need to close the grey valve to avoid contamination with black stuff.

Silicone spray on the valve blades frequently is all ya need to restore their sealing and operation. If not replace the entire valve. I think I've done it twice on my black tank, never on the grey. Yeah, it's a poopy job.

-- Chuck
I drilled into the plastic housing above the pull sliders for my black and gray drain valves. Then, I installed a nominal 1/8" brass plug into the holes. (Buy the plugs at your hardware store to figure out what drill size to use. I actually used a tap to put in proper pipe threads.)

This area does not get tank fluid on it at any time, so there is no risk to getting sewage backing out of the hole.

When the valves get a bit sticky, I remove the plugs and spray silicone into the holes. I can do this when the valves are closed if I am having trouble opening them. And, when the tanks are drained, I spray silicone into the holes while operating the slides back and forth.

It works like a charm. Photo attached.

–Gordon
 

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I drilled into the plastic housing above the pull sliders for my black and gray drain valves. Then, I installed a nominal 1/8" brass plug into the holes. (Buy the plugs at your hardware store to figure out what drill size to use. I actually used a tap to put in proper pipe threads.)



This area does not get tank fluid on it at any time, so there is no risk to getting sewage backing out of the hole.



When the valves get a bit sticky, I remove the plugs and spray silicone into the holes. I can do this when the valves are closed if I am having trouble opening them. And, when the tanks are drained, I spray silicone into the holes while operating the slides back and forth.



It works like a charm. Photo attached.



–Gordon



Nice fix! I might just copy that. Thanks for sharing.
 
After several full tank flushes it has appeared to of cleared any debris. Thanks for all the suggestions.
 
I had the same problem, didn’t get lucky like you and had to actually change the 3” blade, on a not new system. Its every thing you’d imagine it to be when taking out the 4 bolts and pulling the old assembly and seals out, maybe worse.

Getting the old one out is messy but very easy. Getting the new one in while keeping the seals in place on both sides of it not so easy. I had to take the valves for the black tank, grey tank and galley tank apart, all the hangers so I had room to slide opening apart enough to get the new blade and seals in. I decided I didn’t want to put it all back together just to test for leaks and find I didn’t get a seal back in and have to take it all back apart/together again so I went to Home Depot and got a 3” black ABS union I added about 3’ down stream of the valve, like the factory should have done from the start to make it all easily serviceable in the future.
 
After several full tank flushes it has appeared to of cleared any debris. Thanks for all the suggestions.



Not that lucky,just slowed the leak about a gallon a day. What valve is used on new Isata 3 . Would like to replace the seals before its used.
 
our black tank valve leak was caused by a poorly routed cable. not hard to fix once you gain access. had to cut through the coroplast. it's amazing how well it works once the cable was able to move freely.

i also bought one of those valterra screw on valves so at least i did not get a rush of liquid every time i opened the cap.
 

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