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Discussion Starter #1
We have a problem with dirty water leaking back into the head after flushing. I understand that it is probably either the joker valve or the flapper in the pump itself. What I don't understand is where is the dirty water coming from?

We always flush with it in the dry position, pouring in tap water as needed.
We don't flush overboard, so those seacocks are closed. We took off the access cover and looked inside the tank. The vent is clear.....we hosed water into that and watched it come in. We can see the fresh water coming into the tank when we flush. That hose is near the top of the tank and the tank has been pumped out. So where is this dirty water coming from? And how does it get to a hose to get back into the bowl?

When we do flush, after about the eighth or ninth pump, it starts to gurgle and splash back a bit as we pump. It does empty and then gradually starts filling up.

We bought a new head 2 years ago because of this. And we have changed the joker valve twice since then. It seems to be ok for a couple months then....bingo! Also, we don't use the head that frequently, only occasionally when we are out overnite. We always use the marina facilities when we are there.

I am not that keen on using a bucket...so any advice would sure be appreciated.
 

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Mud Hen #69, Mad Hatter
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Check also for a blocked vent on the holding tank. Wasps like to pack them with mud and/or solids plug it from the tank vent outlet and that creates a pressurized holding tank that defeats the joker or flap valve.
 

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Discussion Starter #4
We did check the vent....that is clear.....we hosed water into the outside vent opening and watched it come into the tank.

Interesting thought about the y valve. But if there was some sort of blockage, I would think it would have cleared up after all this time. The problem has been going on for a very long time, only periodically clearing up for a short while whenever we change the joker valve.
 

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Does the discharge hose from the head have a vented loop? Typically the hose runs up to a vented U-Bend mounted up high above the head. When you pump rapidly you push all the liquid up over the loop and you pump some air too. Because of the vent the liquid falls down the other side of the bend into the tank. A siphon can't start ' because the vent lets air in. My experience is that these vented U-bends have a check valve that prevents the pump from pushing liquid out through it. This check valve may have a little o-ring seal. They are eaily clogged and the o-ring can swell and cause it to stick closed. Then waste will siphon back from the tank into the head. this sounds like what is happening to you. Of course if you don't have the vented loop, then you most likely WILL have this problem!

The Joker valve is part of the pump. It looks like a check valve to prevent reverse flow after pumping out. However, since it handles solids it is nearly impossible for it to seal well enough to prevent leakage back into the head. It works okay when pumping out because the pump moves a large volume and a little leakage doesn' stop it from pumping properly. This is why you need the vented loop.

Hope this helps,

Gary H. Lucas
 

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Discussion Starter #6
The discharge hose does have a vented loop. Whether or not it is blocked is unknown.....we would have to cut away part of the wall to get to it. But that can not be the problem. I can pump over a quart of clean water thru the hose and watch it come into the tank. The dirty water would be at the bottom of the tank....at least 6 inches below the discharge hose.....so no way it could siphon back up into the hose.


Also, I don't know if it is true or not but someone told us recently that you do not need the vented loop if you don't pump overboard. Anyone know if that is correct?
 

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Old Fart
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Vented loop

A vented loop in the toilet discharge is needed only on the discharge line that goes directly overboard. It's to prevent siphoning back water and sinking the boat. A discharge line that leads to a holding tank should enter the tank at the top so no vented loop is needed.
 

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Discussion Starter #8
Well it should be an interesting (make that smelly) weekend because we are determined to get this fixed. Will try the y valve first, because changing the joker valves is always just a temporary fix. But the y valve appears to be stuck in place. Has not been turned to do overboard discharge in a lot of years. Too much force might just break it off. Oh well.....will hope for the best on that!
 

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The discharge hose does have a vented loop. Whether or not it is blocked is unknown.....we would have to cut away part of the wall to get to it. But that can not be the problem. I can pump over a quart of clean water thru the hose and watch it come into the tank. The dirty water would be at the bottom of the tank....at least 6 inches below the discharge hose.....so no way it could siphon back up into the hose.


Also, I don't know if it is true or not but someone told us recently that you do not need the vented loop if you don't pump overboard. Anyone know if that is correct?
I started a siphon going yesterday, from a tank about 3 feet off the floor into the top of an 18" tall tank on the floor. We didn't want anyone tripping over the hose so I pulled the middle of it up about 7 feet above the floor. It's been running continuously for two days. A siphon will work to a height of over TEN feet!

Are you sure the tank connection your head is connected to does not have a tube down to the bottom of the tank? That would be the case if the fitting was really intended for pumpout.

Gary H. Lucas
 

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Aeolus II
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Take 2 Aspirin and call me in the morning... Sorry, I couldn't resist.
 
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