Difficult waste tank valves

Dayle1 · 03-08-2016, 05:43 PM

Well after 5 yrs use, the cable valves have become way too difficult to operate. It takes all the strength I have to open them. I tried mineral oil on the seals and spray lube on the cables, neither made any difference. So, I dropped the underbelly and disassembled the valves. What did I learn? The problem is not the cable being tight, twisted, or crimped. In fact once the black tank valve was clean and hanging loose it was an ez two finger operation.

The problem was solid waste, soap, etc that builds up inside the valve body behind the gate valve. This is what made it very difficult to open the valve with less impact on closing the valve. The issue is how Crossroads and probably other manufacturers install cable operated valves. In an ideal world, the valve body and valve stem would be vertical so that gravity and constant operation would keep solid waste from building up around the valve. Worst case installation would be with the valve body down. But neither of these are practical options. Horizontal is practical but not much better than straight down. But Crossroads does even worse than horizontal, they install the valves rotated about 30 degrees down from horizontal. While this makes it ez to route the cable under the tanks, cross members, etc., it is guaranteed to leave solid waste building up behind the gate valve with no way for it to drain or be flushed out. With a little more effort, the valves could have been installed at least 30 degrees above horizontal. Making the change now would be more difficult.

**mark5w** · 03-08-2016, 06:09 PM

Larry, do you have any pics of the valve the way it was installed?

Donjamin · 03-08-2016, 08:28 PM

Larry,

What type of tank treatment are you using? Is this problem with your black tank, grey tank or both?

D.

harley · 03-09-2016, 08:51 AM

This would be a good project for Christines new replacement,Kathy Fuller.

travelin texans · 03-09-2016, 09:13 AM

I use a good healthy squirt of el cheapo dishwashing liquid after draining & flushing the black tank & then filling/draining til suds are gone. I have also added approximately 1/4 cup of el cheapo cooking oil to each tank after draining, both method worked for me.

Dayle1 · 03-09-2016, 02:10 PM

The issue is not what type of lube is used or how frequent, although these certainly are a factor. The issue is this, the valves are installed with the shaft pointing below horizontal. All waste water contains solids that will settle out of the water, especially when the water is not moving, this means that solids can build up in the cavity that the blade needs to retract into when opening the valve.

I've cleaned two of the valves so far, not too difficult. After lowering the valve so the shaft is higher than the blade and removing the seals, I put a bucket under the valve and use a spray bottle filled with soapy water plus operate the valve a few times to flush out the solid residue.

BTW, I've research electric operated valves and at least one manufacturer specifies that the valve must be mounted with the shaft between the 10 O'Clock and 2 O'Clock positions.

I fully understand why CR installs the cable valves the way they do and don't expect that to change. But this is more of an FYI, for those that have had their cable operated valves fail or difficult to open, then most likely it is not the cable, but the residue inside the valve cavity. Now if each of the valves had a mini flush line installed into the valve body, that would be ideal.

Just to add this, my black tank treatment is 3-5 flushes after most dumps. Then adding a 1/4 cup of Dawn and about 10 gallons of water prior to the drive home. Then dumping at the house with several more flushes. Finally, several times each year, I again use Dawn and fill the tank to the bottom of the toilet (which puts soap suds out the vent pipe), let sit 24 hours and then several flushes.

geondebi · 03-09-2016, 08:20 PM

When my PP was only two years old the black tank would leak when you opened the cap. Besides the valve I added to the hose connection point I wanted to change the valve. I pulled the bottom cover and found the valves and removed the black tank valve. In replacing the o rings I could not get them to seat with out rolling. When CR built the trailer the installed the tank and glued the pipe. That to say there was not very much movement or room to pry the valves apart to insert the new valve. I had to end up putting in a union to get some movement. I was a real pain but got it done and works fine now.

bandb · 03-10-2016, 03:30 AM

When I was surprised by some waste water pouring out when I took off the sewer cap it was apparent that the black valve was not closing completely. I followed the suggestions on the forum and added a gate valve at the end of the sewer pipe. After getting so irritated by the difficulty of opening and closing the black tank valve I cut into the sewer pipe and added another gate valve so I now leave the cable operated black valve open and use the gate valve for dumping tank. It works great!
Bruce

Dayle1 · 03-10-2016, 06:19 AM

Quote:

Originally Posted by bandb

When I was surprised by some waste water pouring out when I took off the sewer cap it was apparent that the black valve was not closing completely. I followed the suggestions on the forum and added a gate valve at the end of the sewer pipe. After getting so irritated by the difficulty of opening and closing the black tank valve I cut into the sewer pipe and added another gate valve so I now leave the cable operated black valve open and use the gate valve for dumping tank. It works great!
Bruce

For a year I have carried a 3" replacement valve and extra threaded rod. I can easily remove the cable valve, drill a 1/4" hole thru the I-beam and switch to a conventional manual valve with no need to redo the lines. But, now I know that the cable is not the issue and that if the angle of the valve is not changed, then residue will still be trapped behind the blade. Hopefully you installed your valve with the shaft pointing up. Maybe it is time to think seriously about adding 3 new valves below the underbelly. I already use the safety valve at the end of the outlet.

TxCowboy · 03-10-2016, 12:50 PM

Quote:

Originally Posted by travelin texans

I use a good healthy squirt of el cheapo dishwashing liquid after draining & flushing the black tank & then filling/draining til suds are gone.I have also added approximately 1/4 cup of el cheapo cooking oil to each tank after draining, both method worked for me.

That, sir, is an excellent suggestion! I never would have thought about that. LOL

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