Forum Discussion

Mickeyfan0805's avatar
Mickeyfan0805
Explorer
Jun 05, 2013

Black tank - small leak into drain pipe.

We've gone out twice so far this year, and both times we have been confronted with the same problem...

When leaving the park, I empty the tanks, flush, and then refill a few gallons in the black tank. I close all the valves and everything seems to seal up nicely. The next time I return to connect the sewer hose, however, I check the valves to make sure they are closed, but when I open the cap on the pipe, it releases 2-3 cups of liquid that has somehow 'escaped' the black tank. Once that drains out, there doesn't seem to be any active leak that I can find.

In summary, it seems as thought somehow, perhaps while in transit, a small amount of liquid is leaking past the valve on the black tank and into the drain pipe.

Any ideas or suggestions (fyi - this is a 9m old unit)?

7 Replies

  • ksg5000's avatar
    ksg5000
    Explorer II
    Jun 06, 2013
    Worst case senario you can replace the gate valve - not expensive. Sometimes you get crud stuck and the valve won't close properly - sometimes the rubber gasket shifts out of place. Try cleaning - if that doesn't work take the gate valve apart and reset/replace gasket as appropriate.
  • camperpaul's avatar
    camperpaul
    Explorer
    Jun 05, 2013
    You can clean the groove in the gate valve with one of those round toilet brushes that looks like a big overgrown bottle brush.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Jun 05, 2013
    After empty, disconnect the hose, then backflush w/ hose nozzle while working the valves open and close. If that fails, replace seals in valves.
  • bmet2000's avatar
    bmet2000
    Explorer
    Jun 05, 2013
    Another cause of my gray tank leak was a piece of plastic, more like a plastic wrap. Not sure how it got in there, but more than likely from the manufacturing process (like a workers sandwich wrapper tossed in)
  • Mickeyfan0805's avatar
    Mickeyfan0805
    Explorer
    Jun 05, 2013
    bmet2000 wrote:
    I use one of the external twist on valves to keep from being "surprised" when I take the cap off. On my camper the distance from the gray valve to the outlet was about 6 feet or so, so depending on the angle of the dump station, I always had water dump out before I pulled the valve.
    You can try and find out why yours is letting some by, but it could just be that it is not angled toward he drain as you are dumping and when you close the valve some is trapped. Some times I drive up on my Lego blocks at the dump station if it is not busy to get better drainage. Some dump stations are on a hill in my area...
    One of these external valves can help when either of your valves fail.

    http://www.campingworld.com/shopping/item/twist-on-valve/27868


    Thanks - the distance from my valve to the outlet is about 6 inches. I know it is clean when I close it up, but it's not when I re-open.

    I'll try to check for the tp or other obstruction issue next time I'm out.
  • bmet2000's avatar
    bmet2000
    Explorer
    Jun 05, 2013
    I use one of the external twist on valves to keep from being "surprised" when I take the cap off. On my camper the distance from the gray valve to the outlet was about 6 feet or so, so depending on the angle of the dump station, I always had water dump out before I pulled the valve.
    You can try and find out why yours is letting some by, but it could just be that it is not angled toward he drain as you are dumping and when you close the valve some is trapped. Some times I drive up on my Lego blocks at the dump station if it is not busy to get better drainage. Some dump stations are on a hill in my area...
    One of these external valves can help when either of your valves fail.

    http://www.campingworld.com/shopping/item/twist-on-valve/27868

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,354 PostsLatest Activity: Jan 24, 2026