sewer dumping problems

[nekraus47]

We bought a 2010 Montana 5th Wheel new and have had problems with the Black tank and one of the Grey tanks dumping. Sometimes it dumps the way it is supposed to, and then the next time it only dribbles when we try to dump. This has been going on since it was new. We have had it back to our dealer twice. They took it apart both times and can find nothing wrong. One gentleman told us that he had the same issue and his dealer cut a little bit off of the vent pipe on the roof to give it more air. We tried it and it did not help our situation. Has anyone else had this same problem, and if so what did you do to correct it.

[SteveC7010]

Originally Posted by nekraus47

We bought a 2010 Montana 5th Wheel new and have had problems with the Black tank and one of the Grey tanks dumping. Sometimes it dumps the way it is supposed to, and then the next time it only dribbles when we try to dump. This has been going on since it was new. We have had it back to our dealer twice. They took it apart both times and can find nothing wrong. One gentleman told us that he had the same issue and his dealer cut a little bit off of the vent pipe on the roof to give it more air. We tried it and it did not help our situation. Has anyone else had this same problem, and if so what did you do to correct it.

Several issues to consider:

With the black tank, it needs a bunch of liquid to drain properly. I like to top off the black tank with water at the campsite before driving to the dump station. Stirs things up a bit if you know what I mean.

Even then, a blockage is possible and may need repeated flushings to move things out.

It helps if the trailer is fairly level both side to side and front to rear. One of the CG's we use a lot has a poorly designed dump station that leaves the trailer significantly nose down when lined up with the dump port so that one of the tanks drains very, very slowly. They drain much better when level.

Check your vent for blockage. It's possible that some critter built a nest in there preventing drainage.

I've also heard stories of the round knock-out's for the drain openings being left in the tanks by sloppy factory installers. If that is the case, then the intermittent draining problems could well be a knock-out up against the drain opening. Sometimes it's there, sometimes not.

Perhaps the best diagnosis possible is by examining the interior of the tanks. Find a plumber's camera, clean everything out real well, and run it up the drain pipe. Examine every square inch of the inside of the tank checking for anything that might cause the problem. A blocked vent might only be visible from inside.

These holding tanks are pretty simple devices and should work fairly reliably unless there is a physical obstruction of some kind.

[ziggyga]

We have a 2012 Cougar 323MKS. The first few trips out with it we were dumping at a station that was slightly uphill. The black tank would not dump, but both gray tanks dumped fine. Took it to the dealer each time and drove on to thier level dump station and it dumped completly.

They investigated and found the way the kitchen Gray and Black tanks are plumbed, If you are on an incline, either up or down, one of the tanks will not completly empty. Poor design but I have learned to live with it. Now when I am at a park with a dump station that is not level, I make sure to stop at the dealers level dump station. (I also store there so I just un hitch and leave it0

This may not be the case with your trailer but it is something to consider