Blackwater Valve

I have noticed when I pull the handle on the slide valve to dump my blackwater tank it seems to function a little strange. When I pull the valve all the way out, it flows for a few seconds then seems to almost stop. I can push the valve back in about 3/4 of the way, and the flow begins again. At this point the valve is only 1/4 open.

As part of a routine maintenance, the previous owner had both valves replaced in February of this year by Marathon in Texas. Since I have never had one of these valves apart, I don't really know how they look inside. I assume it is just a flat blade that moves out of the way and allows the flow. I don't understand why the flow would decrease when I pull the handle all the way out?

Can someone shed some light on how this might be happening? It's not really causing a problem, but I would like to understand what is going on.

Dale,

Sounds like you have a Krakman sized Anaconda wedged in your tank that needs extraction.

Just flush these down the tank and you'll be in good shape. Remember to have the valve open.....

Attachment 3267

Jerry, I can't believe how fast I got the solution to my problem. Since I don't have any of these, how about bringing some of the Trick Balls to Spearfish? I am sure this is probably the solution, but I don't think I fully understand the theory behind it.

Dale,

Unfortunately, or luckily if you are the Krakman, I won't be in Spearfish, but I am sure the ACME truck has already been there and will be making another stop prior to the rally.

Dale,

I'll have the Acme Balls with me in Spearfish!:eek:

It almost sounds like a vent problem. On my grey water, it flows real fast for a few minutes and them almost stops until it vents (you can hear the woosh) and then empties. My black water full flows without any stop until empty.

If it is a venting problem there will be a distinct oil canning sound as the tank goes to a negative pressure and then returns to atmospheric pressure.

It sounds like there is some blockage and moving the valve reorients the blockage.

May I assume the practice has been to let the tank(s) fill before dumping so the pile of poop is pushed out with the water flow? Some folks who stay in one spot for an extended time period leave their valves open and the net result is a serious accumulation of solids that accumulate over time and can create future dumping issues.

On a subject not related to the elimination of waste directly, I found a part for my shower drain, the strainer, that started to discolor and the holding tabs were beginning to break.

It was available at Lowes. Mine is a 4 1/4" strainer and brass. I found the exact brass piece and I'm happier than Truk is that JDUB is not going to Spearchucker. It's made by Oatey #420043.

Jon, I empty the tank once a week. It is usually about 3/4 full. I think it has been acting the same way all the time, so I am assuming there is not a blockage, but I really don't understand why it is working the way it is. I may try opening the valve and have Paulette flush the toilet at the same time. I assume that would tell me if there is a vent problem.

I dumped the tank again to see if I had a venting problem, but I didn't get a repeat of earlier performance. I opened the valve wide open, and it all drained out. I had Paulette flush the comode, but that made no difference at all. "If" I have a problem, it must be in the valve itself, but I don't understand how that could be. I guess I'll wait and see if the same problem arises again.

I usually dump the black tank once a week, and I flush the tank each time, so I am pretty sure there is no build-up of any kind on the bottom of the tank.

How would one replace such a valve? Is it complex?

Adam

There are some things that can fail on our coach that we do not even want to think about.

This is one of them.

Everything on our coach can be fixed, including the waste valves. Fortunately they are very reliable except when you drive over something that damages the assembly. I won't name names but there are some on this forum that can tell you how to go about making the repairs.

Can we change the topic?

Dale,

FYI... My black valve was hard to pull. I drained the tank and rinsed real good a couple times. I then removed the 4 bolts that hold the blade in place and was able to move the blade box around and lube it with silicone. I think it could easily have been removed from the plumbing, but I didn't need to go that far.

This is only for our vintage CC's, as the plumbing is fixed and glued in place, but the knife valves can be moved around and/or removed I believe for replacement.

Or, call Jdub, he is the resident stink expert!:D

Why is it when someone can't name names, my name will eventually appear?

During the infamous J. Buffett "ROCK" concert incident I did remove my 45 degree dump pipe hookup. Requiring a new valve in the process.

Actually a pretty easy job, after you get the tank emptied. Since there was a clean break, there was no way to hookup the hose. So we headed to Chicago to find the Dave Matthews Memorial Bridge.

After emptying the tank it's just an unbolting, and possibly pvc cutting job. I'll try to provide some pixs later on.

One trick I learned from Trukman (why is it he's the goto guy when it comes to pooh.) is that after emptying the tank, and before removing the valve, use your low level system to lean the bus AWAY from the opening. You might also want to have a box of disposable gloves on hand.

Mike

Funny, I did not see your name appear except on your post.

I do recall that the Mothership was a part of several poop chute stories. Care to add any more detail for our newer members?

Remember, you outed yourself.

Haven't performed this task myself, but I've helped another guy replace his.

Not a major job by any means BUT it is VERY IMPORTANT to make sure the waste tank is completely empty. Tipping the bus away from the outlet is a great idea..... and still be prepared for a little "spillage" which is unavoidable.

It's also a good idea to make sure the replacement valve is well lubricated when installed, as it will ensure smooth operation for a long time.

Good luck!

I just removed my broken 3 inch waste Coupler which was damaged by a small boulder as I turned a corner in a RV park. I noticed Liberty had glued the fitting into the PVC 90 with silicon instead of PVC glue. It made it much easier to remove the damaged part w/o breaking the 90 degree fitting. I'm thinking this might be a well thoughtout consideration by Liberty.

Gary,

I think thoughtful consideration is not having the thing hang down in the first place. Our Royale had that issue, but we are free from it now.

Attachment 3279

We also learned at OSH that you can swivel this set up where the discharge comes straight out so the honey wagon can easily hook up. And the valves are easy to change and service, unlike the Royale where you also had to get on your knees to hook up the dump hose.

That is a nice set up . Liberty has one holding tank however and the drain outlet for the tank is at the very bottom. It looks like Marathons 2 tanks are elevated.

Quote:

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Originally Posted by Roadrunner

I have noticed when I pull the handle on the slide valve to dump my blackwater tank it seems to function a little strange. When I pull the valve all the way out, it flows for a few seconds then seems to almost stop. I can push the valve back in about 3/4 of the way, and the flow begins again. At this point the valve is only 1/4 open.

As part of a routine maintenance, the previous owner had both valves replaced in February of this year by Marathon in Texas. Since I have never had one of these valves apart, I don't really know how they look inside. I assume it is just a flat blade that moves out of the way and allows the flow. I don't understand why the flow would decrease when I pull the handle all the way out?

Can someone shed some light on how this might be happening? It's not really causing a problem, but I would like to understand what is going on.

---

I have had a similar problem and I assumed is is some type of air lock that occurs. If I shut the valve and reopen it flows properly again.

Pam thinks its a build up of Gas, I'm not buying that one, but we do eat lots of tacos.

Dale, Getting this Thread back on track, I have noticed the same thing you posted at the beginning. I have always thought it was toilet paper jamming up at the discharge bend. I wonder if Septic Tank approved paper is better to use. I have also seen Buses at different repair facilities with the same issue. They call it " A Clog " and the new guys always get stuck with the job.

Jim, The one thing I don't understand is that if it is really a clog, why would it drain fine as soon as I push the valve back in to about 1/4 open. That would seem to be reverse logic. You would think if it is clogged when open all the way, it would surely be clogged when only open 1/4 the way.

There surely must be a logical explanation to this if it is happening to others. It has never been a problem, just a mystery. I am considering the disassmbly of my valve just to see how it works. I am surprised that someone hasn't taken one apart and has a picture of it.

Whatever you do, do not, I repeat, do not get down there and look up that pipe to see why it drains slow.

I read somewhere recently that according to consumer report that Charmin, and Angel Soft toilet paper disintegrate quickly.
It might be worth a try of either of these, before you bothered to disassemble anything.

It is possible that if paper is blocking the knife (guillotine) valve that when one pushes the valve even partially closed that, that movement is enough to cut and dislodge the blockage.

You could drain and thoroughly flush your tank, then to make a test refill the tank,(with clean water only) and drain it as though it were black water. If it acts the same as with real black water you can then check for a venting problem.
If the water drains uninterrupted and in a fashion acceptable to you, then look at the tissue issue, or perhaps something more substantial as the culprit.

I don't think it is the valve itself per se. If the valve moves freely and seals whatever it is controlling then it should be OK. If there were a material lodged in the valve permanently, then it would (never) function properly.

I'm with Jim on this. Vent problem. With the valve wide open the fluid is going out faster than air can replace the space, and it can not gulp air thru the hose so the flow stops.

Does your washer/dry vent into the black water vent pipe, possible causing lint to build up in the vent pipe.

GregM

I once did an experiment to see how toilet paper dissolved. Put a sheet in a bowl of water for a few days. Tried several different brands. Most do not dissolve at all.

The RV specific brands do fall apart after about 3 days.

Since we use the same toilet paper that we used in the Marathon, I am inclined to believe that the paper is not the culprit. I never had a problem with the Marathon. I am wondering if it is something with the design of the system that causes a vent or draining problem.

If this was a venting problem I am certain Dale would hear the oil canning as the tank drains, then bubbles work back up through the drain to restore atmospheric pressure to the inside of the tank. Also, before that happened he would hear every trap inside the house, in the shower, the sinks, etc. being sucked dry. Paulette would hear each trap gurgling as air is pulled through them.

It isn't a venting issue.

In the opening post, Dale stated that if he reduces the flow to 1/4, then the tank drains just fine.

That says to me that the valve will flow freely, because there is a venting to the tank that will support that flow.

If the tank valve is open full then possibly there is not enough venting to support full flow?

The valve at full flow could , because of the configuration of the fittings, and or the area where the valve is mounted, be causing a turbulence that disrupts the flow?

What is not known is if that particular tank and valve combination ever drained the way Dale expects it to, nor if the valve in question is the original valve, or some replacement by a past owner, or if there is some article submerged in the tank that is moved over to the inlet to interrupt the flow when the valve is at full flow, but held at bay at 1/4 setting to allow draining?

The tank could be oil canning and Dale has not heard it. I think his tanks are polyethylene, and not stainless, and would have a much quieter and dull sound to them. They could also be covered in insulation?

I am only guessing here as is everyone else. It's now up to Dale to take it apart and come to a conclusion. :eek::eek::D

Dale,

Did you not read what I posted? Take the valve apart.

Has Jdub been in your coach?

I agree with Truk.... the only way to know for sure if the valve is working properly is to open it up and take a peek :(

Not the most enjoyable of jobs, but relatively easy and you'll know once and for all if the valve is the culprit....

Remember:


Empty.

Lean.

Glove.

Inspect.

mm

Jim C., Note that in my first post, I said when I open it all the way, and it slows down. I can close it down until it is open only 1/4 of the way and it flows freely. I am going from 4/4 open to onloy 1/4 open.

I have drained the tank twice since I made the first post, and it seems to have drained fine with the valve open all the way. I do agree with Jon that I don't think it is a vent problem.

I think what I need is someone with experience working on this kind of problem!

Because of the nature of the holding tank valves, if the tank is ventilated, and the valve is fully open the flow should literally fill the sewer hose. If it is a venting problem no matter if it is a metal or plastic tank there will be noises that can not be ignored.

So assuming the venting is OK which I strongly believe to be the case, the only reason for a flow interruption would be material inside the tank that is larger than the opening, or a valve that is not fully opening. I will assume Dale is fully opening the valve. That matter in the tank is likely to move around and block the opening sporadically. Before I chose to start disassembling the drain valving and look into the tank to see what is going on I would try some enzymes to digest the material every time I emptied the tank to see if mother nature could digest the waste.

My criteria for deciding to disassemble the valving would be when the drain time starts to take longer than the repair job will take. Until it reaches that point I would find things to do while my tank is draining.

Dale,

After you have drained the tank, have you held a mirror under the opening, and with a goose neck flashlight, looked into the opening to see if there is something blocking it?

Denny, I haven't tried looking in the drain. It always drains with no problem. I just don't understand why it would seem to drain faster at 1/4 open compared to wide open. If I really start having a problem, I will take it apart.

I was originally just wondering if anyone else had ever had a similar problem or if anyone had dissambled one of the valves. I may have to install an electric valve just so I can get that "other" crowd off my back.

Dale, If you quit picking on us Liberty guys we will quit picking on you.

These valves are nothing more than a sliding gate like a guillotine. As it is opened the blade just retracts leaving an unobstructed flow path. I still believe that you have something in your tank that moves towards and blocks the opening. The greater the opening the more that foreign matter is pushed towards the opening thus blocking the flow path. With reduced flow that obstruction isn't pushed into or towards the opening.

Our push button valves are the same valves you have except instead of pulling a tee handle we actuate an air cylinder that pulls.

If you pay me $5.00 I will let you see the push button at Spearfish. If you pay me $10.00 I will let you push it.

Jon, I'll go for the $15 option. Your crew removes the valve, looks in the tank, and drains and flushes, in that order.

Or I may get industrious and take this valve apart this week just to make sure I don't have a blockage.

Dale,

My people have considered your fine offer of $15 and have decided to forgo the opportunity to earn four gallons of diesel fuel.

It would appear your problem will require your personal touch.

Don't forget to tip the bus AWAY from the drain.

Dale,
I wouldn't worry about the other group getting on your back. That simple valve is much easier and less expensive to replace than the complicated electronic ones. Besides, you still have to get out and place the hose onto the valve and into the dump station. So what are you saving by having an electric valve unless you want to dump while moving down the road? Although, I do remember seeing a photo from a previous POG rally where someone did hit the switch and let the contents flow onto the nice concrete pad they were parked on. I guess there is something for everyone.