I have cable operated Valterra/Bladex dump valves that failed to operate. I know that the cable type can be troublesome, so I explored the reason for the hard operation. I found the cables were not the issue, they moved freely. It turns out that the blade seals pipe to pipe just fine but there is no seal to keep "stuff" out of the area where the blade is when retracted. I sawed the valve apart to verify the fact and it was a mess in there. Given the fact that buildup is inevitable, the life of this type of valve is limited. Of course a direct rod operated one can be used till operation becomes extremely difficult, but a cable will buckle. I installed tubing from the inside of the new valve and ran it along the cable. If operation begins to stiffen, I will shoot silicone or something into the valve.If there is a better design out there, please let me know. It appears the electric models just use the faulty design.

Well of course there are better valves. But probably aren't ones that you will be buying. Generically that sort of valve is a "knife edged gate valve". And there are a multitude available in industrial catalogs: McMaster-CarrThose are heavy metal ones and a bit pricey you'll notice. But they do have PVDF seals. Most valving of this sort shows up in the manufacturer's specialty catalog and not general catalogs. They are available in many materials from engineering plastics thru exotic alloy's like Carpenter-20. You can get all sorts of operators from handwheels thru electric or pneumatic operators. Some examples:imagesWhen I was buying things like this we thought nothing of spending $600 or more for a small 1 inch valve. The prices go up rapidly when you add options.Just remember that: "An engineer is someone who can do a $100 job for $10" and that's why the valves on RV's are not top of the line. They do the job at a low cost.

After dumping... could a person disconnect the dump hose, then leave the gate valve open and flush back up in the area with a forceful large volume of water? Is there any way to access it?I've never examined one of these in detail. Just wondering if it could be done.

Also why it is important to flush some clear water down after pulling the valve. You need to wash any cling on's off of the valve. That will keep the valve and seat clean and working easy. Plus it helps avoid the leakage that sometimes happens when the valve does not fully close and you get a surprise when you remove the end cap to dump.

coolmom42 wrote:After dumping... could a person disconnect the dump hose, then leave the gate valve open and flush back up in the area with a forceful large volume of water? Is there any way to access it?I've never examined one of these in detail. Just wondering if it could be done.There are elbows and extensions with hose attachments for backflushing. Get a clear one and you can see what comes out.There is also an end cap valve which is useful if leaks happen.

The usual cause of debris in the valve body cavity is the practice of LEAVING the valve OPEN while camped. This allows the slower moving liquid/solids to fill into the normal gaps in the valve cavity. When you dump a tank with liquid in it, the rush of debris/water is enough to keep the debris from settling in the valve cavity. Once the debris is in the cavity, there is NOTHING to do except pull the valve and manually clean it out. Cable operated valves, it is easier to clean out once the valve is pulled. Rod(Handle) driven valves are harder to clean because the odds are the debris has been FORCED into the valve body because you can push harder and the cable will just flex. But, backflushing or trying to install a chemical will not get rid of the debris in the valve body. You have to dig it out with a screwdriver. Doug

Is there a better dump valve? | Good Sam Community

23 Replies

Lynnmor
Explorer
Jun 04, 2017
suprz wrote:
I dont think i have seen any dump valve with a different configuration of the seals / blade location or tolerances. The only thing i could suggest to try is to see about getting a new set of seals for the valve from the manufacturer or rv dealership parts dept. to help mitigate the issue. In any case good luck with your search, and dont let folks get to you on here.

Thanks for the input. I did try to point out that the seals are completely out of the picture when the blade is pulled open. With the valve open, there are gaps on each side that let anything flow into the area around the now open blade. I was hoping to find a brand that does a better job of blocking that opening.

Valves that are directly operated may only exhibit somewhat stiffer operation, but will continue to work. Cable operation cannot push a valve closed that has much increase in drag. Folks that do not have cable operated valves should not compare their experience and should not be commenting.

I do understand the problem, having dissected the valve and saw the gunk causing the drag. There is no way to keep any and all material out, with the sewage gushing thru the open valve, a small amount will go into the aforementioned gaps.

I looked at electrically operated valves and might do that next time. The thing that I found is that all the switches are for interior use only and I don't have a convenient place. For now, I have replaced the entire valves on the gray and black tanks.
msmith1_wa
Explorer
Jun 04, 2017
The only solution I can think of would be to install ball valve of the appropriate size. Provided the pipes are long enough. This probably won't be easy. And definitely not inexpensive.
suprz
Explorer
Jun 04, 2017
I dont think i have seen any dump valve with a different configuration of the seals / blade location or tolerances. The only thing i could suggest to try is to see about getting a new set of seals for the valve from the manufacturer or rv dealership parts dept. to help mitigate the issue. In any case good luck with your search, and dont let folks get to you on here.
j-d
Explorer II
Jun 04, 2017
Our valves, with cable extensions, are installed at 90* and have worked since the coach was new including nearly 04 years full-timing. Recently, black started to leak. I added one of to avoid "surprises" when I take the cap off.

But!!! About that time, I started a tank flushing process where:

1. Dump Tanks, Black then Gray
2. Leave Black Valve Open
3. Block Toilet Open
4. Pour 3x 2.5 gallon buckets of water down toilet
5. Notice Coach Drain runs Clear
6. Secure everything as Usual

I no longer find that the cable valves are leaking out toward my add-on valve.

I'd think a tank flushing system would help, but we don't have one and I started doing this. It seems to help.
fpresto
Explorer
Jun 04, 2017
What is sad is that if even a small portion of what you said is correct them almost none would work but by far the majority seem to work fine. How do you explain that? By your theory they would all plug. In 30 some years, through multiple RVs, I have never had an issue. No member of the club I camp with has had an issue except for one who had the handle come off. Proper dumping and flushing will keep the valve clear whether you wish to accept it or not.
Lynnmor
Explorer
Jun 03, 2017
It's a shame that one cannot post any kind of issue without being accused of being the cause. Ask a simple question about replacing a part with one of higher quality and the subject causes the finger pointing and not any mention of alternate parts.

I explained about an open area in a dump valve, even posted a photo, and the clear message is lost by those that need to pontificate. SAD
dougrainer
Nomad
Jun 03, 2017
Lynnmor wrote:
With just one person needing to work on "thousands" of dump valves, one might conclude that there may be a problem.

Well, smart ***. There are Tens of Millions of dump valves out there. MOST of the ones I fix are CAUSED by the RV owner. NOT a defective valve. Doug
Lynnmor
Explorer
Jun 03, 2017
With just one person needing to work on "thousands" of dump valves, one might conclude that there may be a problem.
dougrainer
Nomad
Jun 03, 2017
I understand what you are saying. But, I have 38 years of working on RV's INCLUDING thousands of dump valves. There is NO flaw as you describe. IF debris is getting where you state, then either the valve or the seals are not to spec. Now, the Valve makers are insistent that the valves be installed either 90 degrees to the ground(95 percent are)or upward or the handle at 12 o clock which is ideal but almost impossible on the majority of installs. Any deviation down from the 90 degree can allow debris to flow into the valve body cavity at the handle end. But your complaint, I doubt I have ever seen it. Usually as I stated the paper/debris is jammed into the end cavity by the blade. Doug
MrWizard
Moderator
Jun 03, 2017
if flow goes into the pull area with the valve around 50 percent open

then the seal is BAD, at that position the blade should be in full contact with enough seal that is there no flow toward the pull shaft area

leaving a valve partly open to dry the tank is one situation that can damage seals
the slide body gets stuck to seal, and the seal gets damaged, when the valve is closed

not saying you did this, but its been know to happen

somebody reasonably commented about leaving gray valve open, and now has tapoles in his gray water tank, stupid frog