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Black tank line

Traveling_Savag
Explorer
Explorer
New to the lifestyle and can't figure out why my black tank line fills while traveling. I emptied the tank the last two times before traveling....and made sure valve was closed. When I get ready to hook up, I opened the pipe to attach my hose and waste pours out. How is it getting past the valve?
12 REPLIES 12

maillemaker
Explorer
Explorer
Traveling Savages wrote:
New to the lifestyle and can't figure out why my black tank line fills while traveling. I emptied the tank the last two times before traveling....and made sure valve was closed. When I get ready to hook up, I opened the pipe to attach my hose and waste pours out. How is it getting past the valve?


My RV is nearly 30 years old. When I remove the outside dust cover to hook up the hose, nothing ever comes out.

It sounds like you are getting leakage past the valves.

An easy way to test is close both valves and remove the outer dust cap.

Then continuously flush your toilet, filling up your black water tank.

If you see water coming out of your dump connection with the gate valve closed, you have a leak.

If not, fill up your grey water tank and see if that is leaking at the gate valve.
1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"

fourthclassC
Explorer
Explorer
FWIW.... I replaced the rubber seals from valtera instead of the entire valve assembly. Mine still leaks a little. I should have changed the entire assebmly- not that much more. I am guessing the blade has scores in it or some abrasion which won't allow it to seal completely eventhough I put new seals in. Pound wise/penny foolish....

Dusty_R
Explorer
Explorer
On our current mh the black tank is ahead of the rear axel, with the dump station. The gray tank is behind axel, there is a built in pump to move the gray water to the dump station ahead of the axel. Because of this maybe a cup of gray water will always come out when the cap is remover when getting ready to dump.
Because of this I have built a way to dump the gray at a different location.

Dusty

opnspaces
Navigator
Navigator
Flushable wipes should never even go in your stick and brick toilet, let alone in your RV toilet.

In over 15 years owning my trailer I have only once ever had something spill out when I open the cap. I'm pretty sure somebody on the storage lot pulled the handle as a joke on all the stored RV's. Other than that the drain pipe is always dry when I remove the cap. I would say if you have more than a few teaspoons full of liquid drain out then you have a valve leak.

Next time you dump flush the tank a few times while rapidly cycling the handles to try to dislodge the paper stuck in the groove. If that fails you can either replace the gate valves or add an additional valve at the cap.

Replacement gate valve

Twist on valve
.
2001 Suburban 4x4. 6.0L, 4.10 3/4 ton **** 2005 Jayco Jay Flight 27BH **** 1986 Coleman Columbia Popup

bguy
Explorer
Explorer
Never never never never never

never never

flushable wipes never never

never never never







never





ever
---------------------------------------
2011 Ram 1500 Quad Cab, 4x4, 3.55, HEMI
2009 TL-32BHS Trail-Lite by R-Vision

Pipeman
Explorer
Explorer
I have found in all my trailers that there is residual fluid that just doesn't get drained. It builds up at the sewer cap so you get your feet covered in ..... I put an end of line valve on my sewer line and now no feet getting wet. I also have a clear elbow at the sewer line end of my hose(at the trailer) so I can see when the grey water gets dropped to clean out the black water hose. Look here- https://www.campingworld.com/twist-on-valve-27868.html?cgid=sewer-connection#start=16&cgid=maintain-your-rv%2Fsewer%2Fsewer-connection%2Fsewer-adapters-valves-fittings
Pipeman
Ontario, Canada
Full Member
35 year Fire Fighter(retired)
VE3PJF

MFL
Nomad II
Nomad II
Has it always done this, or just recently? It is common for residual water to remain in longer pipe when draining. Then with travel/moving, it gets to the dump exit. If you are talking about a quart-half gal, this is likely your issue. More likely to be gray water though, than black tank water.

My galley tank has a long line to sewer exit, and has done this since new. My solution was to install sewer cap, with garden hose attachment and small cap. I can loosen small cap, hold hose under, open small cap to drain residual, before opening large cap to attach hose.

Jerry

sempka
Explorer
Explorer
If the valve is a pain to get at, see if you have enough clearance to another valve at the discharge point.
2000 Holiday Rambler Admiral

blownstang01
Explorer
Explorer
Assuming this isn't a new unit, replace the valve. They are cheap and easy to replace, the gaskets get worn after a while and leak.

ItsyRV
Explorer
Explorer
How are you making sure the valves are closed? If you're having leakage, I would not rely just on the valve handle's location as an indicator. Do you do a water dump (pour a few gallons of water into the tank) after closing the valve to see if any leakage is occurring?
1994 Itasca SunDancer 21RB - Chevy G-30 chassis.

1492
Moderator
Moderator

DutchmenSport
Explorer
Explorer
How much is getting past? Is it a gusher, like when you empty the tanks, or is it a tickle?

If it's a trickle, it could be a bit of residual water left in the pipe that didn't drain out completely. You put the cap on and there was still some fluid in the pipe. I know, that just doesn't sound right, but sometimes they can drip for a while after the valve is closed. There is some distance from the valve to the end of the pipe.

Or...

The slide valve is not closing all the way. Toilet paper, gunk, or anything could be caught in the slide valve, where it seals in the track. If this is the case, then...

One thing you can try to do, is empty the black tank and flush it out by backwashing (if you can do that), or black tank flusher, or with a toilet tank wand down the toilet. Clean the tank out, and get it as free of "gunk" as possible. Now that it's cleaned out and empty, fill the tank with about 5 or 10 gallons of water. Make sure the valve is closed. Make sure the cap is on the end of the outlet. After adding the water, move the slide valve in and out several times. What you are trying to do is clean off any gunk that may be caught in the groove the slide seats in. The reason for the clean tank is to ensure no new "gunk" will get caught in the slide valve. Sliding back and fort several times (might) clean it free. Now, open the end cap and let the "gunk" run on out (and hopefully it's not too nasty.)

If that does not work, they do make some products to help clean the slides by adding it to the tank water. I've tried a couple of these, and found them not to be very effective. Vigorously moving the slide back and forth did more good than anything.

And there is a third possibility. The valve is sealing good, but when traveling, it wiggles open. I can't imagine this happening, but if the tank is empty (they are never truly empty) there would be no back pressure on the valve allowing for it to slide. Or it's possible, if your slide is operated by a cable, the cable is not letting it shut all the way.

FYI, even though your tank may appear to be empty, as soon as you move the camper, the fluids on the bottom of the tank will move around and eventually find the outlet. As said, there is always some left in the tank, unless you can turn the camper on it's side and shake it out.

Try cleaning the slide first with the water method. See what happens. There's no cost involved there, and I'm a firm believer in doing the least evasive "thing" first.