Question on black tank problem

**grassmaster** · 09-19-2020, 05:46 PM

We have a 2017 337 rls. Yesterday when dumping the holding tank upon exiting the camp ground, the black tank washer/sprayer would not wash the tank---When I turned on the water supply to the black tank, no "clean" water was coming through the drain hose after the black tank was empty. (the black tank had drained ok) Instead, a few seconds after cutting on the fresh water hose to clean the tank, water was running from the underbelly near the low point drains. I verified fresh water was coming through the hose and at reasonable pressure/volume. It seems as if the fresh water supply line to the black tank sprayer came loose. I had no problem with water leaks during the 4 nights at the campground and hooked up to "city" water.
Before I take down the coroplast to inspect the black tank, is there any recommendation. (Other than my wife's saying maybe we need to trade because I spend time working on this lemon than we do camping. She's sort of right; its had its share of problems.) Anyway, any advise will be greatly appreciated.

**Always Learning** · 09-19-2020, 06:13 PM

Pull the back wall in the basement and start looking in there. On my 2020 337 the black flush hose goes from the Nautilus up behind the shower to a vacume break valve then down to the black tank. If there is no problem there, water all over, then you need to drop the belly cover from the front to the entry step to gain easy access to the tanks.

**gbkims** · 09-19-2020, 06:15 PM

I'd wonder about the vacuum break valve or it's hose leaking.

A Hidden Leaker Waiting To Happen - https://www.mygrandrv.com/forum/show...ting-To-Happen

**grassmaster** · 09-20-2020, 04:15 PM

Just an update. Yesterday, I checked the vacuum break, no leak detected, pulled the panel in the basement, no sign of water. There was about a quart or so of soapy water in the basement. The black tank sprayer is now working like it should, whereas friday no waterflow was going through it. All my test were done while hooked up to city water. Filled and dumped all three tanks to try to duplicate the problem, including the leaking from the underbelly and couldn't do it. I'm at a loss.

**Always Learning** · 09-20-2020, 05:08 PM

Originally Posted by grassmaster

Just an update. Yesterday, I checked the vacuum break, no leak detected, pulled the panel in the basement, no sign of water. There was about a quart or so of soapy water in the basement. The black tank sprayer is now working like it should, whereas friday no waterflow was going through it. All my test were done while hooked up to city water. Filled and dumped all three tanks to try to duplicate the problem, including the leaking from the underbelly and couldn't do it. I'm at a loss.

That is just strange. It must have been two different problems. Soapy water would be grey tanks or washer if you have one. Good luck.

**grassmaster** · 09-20-2020, 05:18 PM

I pull both gray tank handles at the same time, after the black tank empties. Could that have overloaded the system and maybe cause a weak spot to leak? I never had this problem before (that I noticed)

**boyscout** · 09-20-2020, 06:11 PM

Originally Posted by grassmaster

I pull both gray tank handles at the same time, after the black tank empties. Could that have overloaded the system and maybe cause a weak spot to leak? I never had this problem before (that I noticed)

That *shouldn't* cause an eruption somewhere but it's no certainty that it didn't. I pull the grays one at a time because they meet (in many GD trailers) in a manifold. Both pulled at the same time results in a collision of their outflows in the manifold, which constricts outflow from the gray tanks and possibly creates enough pressure there to back sewage up into places it doesn't normally flow.

That doesn't explain the temporary failure of the black tank flush system... that's an odd one. Hope the gremlin has moved on permanently.

**Always Learning** · 09-20-2020, 07:20 PM

Originally Posted by grassmaster

I pull both gray tank handles at the same time, after the black tank empties. Could that have overloaded the system and maybe cause a weak spot to leak? I never had this problem before (that I noticed)

I pull both grey tanks at the same time after I have emptied and closed the black tank and never had a problem.

You said you found soapy water in the basement. Are you referring to the pass through storage area or the area above the belly cover? Did you drop any of the belly cover and look for leaks?

In your first post you said the you flushed the black tank and water came out the belly by the low point drains. Start at the Nautalis and make sure the hose you are flushing with is not leaking at the connection to the Nautalis. If it leaks it will run all over and get into the underbelly. From the back of the Nautilus trace your flush hose up to the breaker valve and down to where it goes in the floor looking for kinked hoses and leaks. Pull bolts out of the belly by the steps and look in for leaks. From the step side you might be able to see the flush hose and connection to the black tank without dropping the belly cover.

Something that is strange is you said soapy water. If the flush hose is leaking then it should be clear water and if the black tank is leaking you will know it from the smell.

I hope you find the problem. It sounds like you have water in the belly which you must dry out or things will grow.

**grassmaster** · 09-20-2020, 07:23 PM

Got me thinking. Perhaps the collision of outflows by pulling both gray tanks caused the vacuum brake valve to activate. Is that feasible? I think since I have her down for inspection, I may replace the plastic vacuum release valve with a more substantial one. If the plumbing is not leaking, the only other explanation for the water is a roof leak. I've been down that road once already and a new roof was put on under warranty because GD didn't caulk around a roof vent.

**grassmaster** · 09-21-2020, 03:56 PM

Update:

Pulled the coroplast and found the graywater tank 2 leaking at the drain connection. Only happens when the tank is greater than 1/2 full. How I can get the nipple, that connects the tank to the drain valve, out the reseal is a mystery. At this point, I don't think I could recommend GD's over other models. Had too many problems with water leaks from one place or another. Oh well, while inside, I'll zip tie all the wiring left disheveled on the floor.
I think they got their quality control guy from the parking lot of Home Depot they day they built mine.