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hondaman900 07-04-2014 02:16 AM

Bizzare gray water blockage symptoms - cant't figure this out
I have an '08 Itasca Sunstar 32K. Gray water has been draining fine at campgrounds etc. until we arrived at our current location and now the tank monitor is saying "full" but nothing is draining out of the gray tank.

Now here's the strange part. I have snaked from the drain valve up into the tank, no blockage. I tap the tank and it sounds empty. I would therefore suspect faulty gauges except I can run water down the kitchen and bathroom sinks, and nothing comes out the gray outlet. I can snake down the shower and bathroom sink as far as my 25' snake's length. Can't find a blockage. The level monitor that showed 2/3rds full is now showing full from running water down the sinks, but where is it going. I only have one gray water tank and it's not going in there. I can hear it entering the tank and nothing flows out of the outlet. There is a growing oder in the bathroom as well - smells like the gray water residue.

So, no gray valve blockage. No tank outlet blockage, I can snake up into tank. No shower or bathroom sink blockage, have snaked them (kitchen sink drain has too small slots to fit snake through). Water drains from sinks but does not enter gray tank. Not leaking water or water flooding in the rig or under-floor storage areas. No water dripping under rig. Level monitor, which has always worked before this, showed increasing levels up until now full. Tank appears to be physically empty. I'm getting stink in the bathroom (and it's not from that burrito I had for dinner).

Any suggestions? I'm afraid of this backing up into our RV and ruining our vacation. What should I try next? Drano? Buy a WalMart backflush attachment (don't want to blow contents back into RV though)? Run a hose down the vents? Remove the vacuum break valves? I've no idea what to do because this one seems to defy logic. We're stuck without being able to use water :nonono:

Anyone come across this before?

mohamer 07-04-2014 02:31 AM

It has got to go somewhere.

Tha_Rooster 07-04-2014 07:28 AM

If I read your post correct you ran a snake from the opening through the valve and in the tank. If so it has to be a sensor if you are sure you made it into the tank.

336muffin 07-04-2014 07:52 AM

Previous owner had a bad habit of leaving the grey valve open with "no problems" you will probably find the blockage is a thick grey matter consisting of kitchen grease, tooth paste, deoderant and so on. It lays on the bottom until dislodged and is thick enough to stop drainage! We purge our grey by filling all of our sinks with hot water and the valve open and drained completely, then releasing the hot water at once. This might take several times to really clean out the problem.
We bought a used coach and found this problem but this solved ours. Let us know how yours is resolved please.

nothermark 07-04-2014 07:53 AM

Not sure about your unit but out MH drains the bathroom sink into the black tank. Ditto shower.

If you keep running water into the kitchen sink does it go somewhere? If so it is getting to the gray tank or you have a leak. I'd start loading water in the kitchen sink until something came out or stopped flowing.

hondaman900 07-04-2014 09:40 AM

I downloaded the plumbing blueprints last night (thank you Mr. Winnebago!) and saw that the shower has its own line to the gray water tank separate from the sinks. I therefore thought that since the water down the sinks test didn't show up at the tank, maybe that line was blocked and the shower which I snaked to the tank was fine and I just hadn't though to test it separately. The bathroom sink has enough plumbing to the tank that the snake may not have made it to the tank. Anyway, the test failed. Water from the shower is not coming out the gray drain - baffling.

I also located the vacuum release ports under both sinks, took them off, still no flow. I thought that if the vent was blocked and causing a vacuum that held back the water that releasing those would address that.

Plunging didn't help either. I now have Drano sitting in the kitchen sink pipes and will fill the kitchen sink with hot water as suggested and dump that down to see what happens - fingers crossed!

hondaman900 07-04-2014 10:01 AM

The plot, or clog, thickens!
This is making no sense. I let Drano sit for 15 min plus as the hot water cooked. Dumped a full kitchen sink, about 4 gals, of scalding water down the drain.

Nothing! Not a drop out the gray tank. What the heck?! :banghead:

Annierufus 07-04-2014 10:03 AM

Is it possible your sink is plumbed to the black tank ?

Joe 1998 Itasca Sunflyer Ford 460

Bobb.25 07-04-2014 10:08 AM

Dump your black tank and repeat the test with the gray tank valve closed, and the black tank valve open.

hondaman900 07-04-2014 10:57 AM


Originally Posted by Annierufus (Post 2122473)
Is it possible your sink is plumbed to the black tank ?

The plumbing diagram shows it to the gray and it's consistent with the observable plumbing/tanks. Also, I've dumped about 10 gallons of scalding water from both kitchen and bathroom and I can hear it going into the tank and its not backing up into the shower or coming out anywhere else. The black water levels should be coming up but are not if it were somehow plumbed into the black. This also worked before, filling the gray through the sinks to get a head of water to flush at the campground, so I know it's to the gray tank.

I'm starting to think there's a sludge "dam" holding the water from the drain. Who knows what the PO put in there. We had it stored on a hill for a year, and maybe a wedge collected in the downhill (rear) side that has come loose on our long trip and has created a dam? Not sure what other theory fits.

Next move is to shove a garden hose up into the tank and turn it on until something comes out. Wish me luck.

timex 07-04-2014 10:58 AM

I would look in all the compartments under the coach to make sure a drain pipe hasn't come apart and is leaking into the storage area.

hondaman900 07-04-2014 11:48 AM

OMG!!! Problem Solved
OMG! I noticed that the plumbing blueprints showed the drain pipes going the other way around and then it dawned on me. My Black and Gray waste valves are labeled backwards. Even the gray and black handles are on the wrong sides. So what I thought was my gray, what I spent so much time rooting around in with the snake, was my black water tank. That sludge was in fact fecal matter - Sooooo gross! I pulled the "Black Water" valve and nice clear water gushed out, all those tests and gallons of wasted hot water. The gauges went down as well. Good thing we're at the in-laws and were using their indoor toilets as otherwise I would have been doing open-heart surgery on the sewer system if this went any further. No wonder the gray water was "disappearing". I was up until 2am last night studying those blueprints and never spotted this until this morning.

I can't believe the factory could get these backwards, install the wrong handles on the valves and apply the stickers the wrong way around. Perhaps some disgruntled employee's idea of a sick joke - who knows. This means that all those times at the campgrounds when I would drain the "Black water" and rinse the hose with "gray water" was in fact backwards. I was apparently rinsing with sewerage - Ugh! No wonder my slinky hose smelled so bad.

Thank you folks for all the help and thank you Winnebago, for even if you were the source of the issue, you do provide schematics for everything online, and that is truly a great resource to have at our fingertips.


JFXG 07-04-2014 12:21 PM

Bizzare gray water blockage symptoms - cant't figure this out
Congrats! Good work!! Glad you found it, and glad you let us know!

No matter how simple, no matter how small, never underestimate the ability of humans to screw something up.

But seriously, here's a question (or four): How long have you been using this RV this way? Do you camp with both valves closed, or "black" closed and "gray" open? Have you never encountered a water drain backup into your shower? Have you never encountered a flow blockage in your sewer, occasioned by a buildup of solids left behind? It seems that in one sense you've been very lucky!

Annierufus 07-04-2014 12:31 PM

On the bright side, just think how clean your gray tank must be

Joe 1998 Itasca Sunflyer Ford 460

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