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Old 07-03-2012, 03:48 PM   #1
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2010 27' FB International
Simi Valley , California
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Posts: 14
Black Tank Flusher Clogged or damaged?

After camping for a week, the black tank was over 1/2 full and we towed home to dump. When we hooked up the hose to flush the black tank there was a high pitched whine and not the typical spraying noise in the tank. Looking into the tank through the toilet, we could see some water running in there but at a very low volume.

I have read all of the threads that I could find on the topic of the built-in flushers and get the idea that they often clog or stop working. Short of a costly repair has anyone had success unclogging it (assuming it's just a clog)? I've thought of filling the tank with water and some sort of cleaning agent.

Could the flushing unit have been damaged while towing with a partially full tank? We usually dump before traveling.

Thanks for any advice you can offer.
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Old 07-03-2012, 05:47 PM   #2
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2006 22' International CCD
2007 Base Camp
Elk Valley , British Columbia
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It shouldn't break as it's just mushy water down there... but they do sometimes catch toilet paper or debris and get plugged. You need to find the vacuum break, which should be right above the tank-flush inlet. As you are filling, watch the vacuum break and make sure it isn't leaking... they can leak if the flush is plugged, which would account for your low flow (and noise).

No worries though, the fantastic Airstream engineers put the vaccum break in impossible places to find, so you, and the subsequent owner, will never see the damage that 10 gallons of tank-flushing water does going straight into the exposed floor of your trailer...
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Old 07-03-2012, 06:13 PM   #3
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2008 27' Classic FB
Burkburnett , Texas
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Here's a pic of what the vacuum breaker looks like on a '08 27FB. Mine is located against the streetside wall under the closet. I had to take out the closet floor to get access to it. The mounting clamp stressed the plastic and cracked it.

I would try to get a visual on it to determine if it's leaking under pressure. Water pressure pushes the piston up and then it overcomes the spring loaded ball valve on it's way to the spray head in the BW tank. I really doubt traveling with a load in the BW tank had anything to do with your symptom.
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Old 07-04-2012, 08:48 AM   #4
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2010 27' FB International
Simi Valley , California
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Thanks. We had read earlier posts about the vacuum breaker. We haven't removed the closet floor but we traced the line via the access doors below the closet. It appears that our breaker may be below the floor. We can follow the line from where the inlet comes though the wall to where it drops into the interior front wall of the shower and down. No breaker. I guess we'll try to pull the closet floor to get a better look.

One thing that does occur to me is that there was no evidence of any water under the closet so either it's not there or it's not leaking......hmmmm.

My hope was that it was just a clog and that we could soak it loose. Now I'm concerned that if the breaker is leaking (and how would we know if we can't get to it), using the flusher will cause water damage wherever the breaker is leaking.
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Old 07-04-2012, 09:08 AM   #5
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Well the bottom line is that as nice as the flusher is, you can live without it. We tend to use ours once a year on the last trip of the year. Technically we always dump the tank full, and if it isn't full we fill it prior to dumping. Prior to getting the Classic which came with the flusher, we always refilled the tank on the last trip and dumped again. Never have had any issues with holding tanks and that final dump doing a refill with clean water tends to do a good job on leaving the holding tank relatively clean.

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Old 07-04-2012, 09:19 AM   #6
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2000 25' Excella
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Originally Posted by Shelly M View Post
When we hooked up the hose to flush the black tank there was a high pitched whine and not the typical spraying noise in the tank.
Thanks for any advice you can offer.
Mine worked satisfactorily for several years, actually, about 10 years, then it started with the "whine" you described, like a pinched hose. During that period, the length of time it took for a complete filling of the tank increased several fold. More recently, absolutely no sound at all, not even the whine. I opened up the compartment underneath, inspected the short piece of hose visible after the fitting, and noted nothing unusual. I did a 24-hour soak, with my usual chemical, nothing exotic, then did a flush with an external attachment and with a wand down the throat of the toilet. I suppose the tank is reasonably clean, but internal flush mechanism is still not operational...silence. There's either some serious residue plugging it inside the tank, or some other in-line obstruction. I haven't checked the anti-siphon (I will next time, but we don't store at home), but I've seen no evidence of water where it shoudn't be, either inside the coach, or under the belly. Hmmm. I'll be watching for your solution.
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