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post #1 of 13 Old 07-23-2012 Thread Starter
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Head basics

The head has been working quite well until after a guest used it yesterday.
I think I cleared it with a lot of pumping and bailing and pumping etc.

I remember that from the beginning it would pump wet and pump dry but only if the thru-valve was open.
Is that normal?
I thought they were supposed to pump dry if the valve was closed.
Am I mistaken.
If not what was wrong?
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post #2 of 13 Old 07-23-2012
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Re: Head basics

Even on the dry setting it may still be creating a bit of vacuum through the sea water intake.
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post #3 of 13 Old 07-23-2012
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Re: Head basics

I'm not quite sure what you are asking, but if you are pumping with the lever on "dry bowl" and it still pumps water then there is a rubber valve that is not seating. Depending on the age and the brand it should be an easy fix to replace the valve. It is a very simple mechanism.

If what you are saying is that it still pumps water with the thru hull water intake valve closed, then the joker valve has probably failed.

I don't know what kind of head you have but this is one of the most common ones:

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Last edited by SchockT; 07-24-2012 at 12:03 AM.
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post #4 of 13 Old 07-24-2012
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Re: Head basics

Not enough info and some confusing terms (pump wet?). Do you mean the raw water intake thru hull or the waste discharge? Is there a y-valve involved to divert to a holding tank that may have been moved?

My first guess is that a guest put a boxing glove amount of TP down your bowl and there are bits and pieces stuck on the rubber flaps, joker valve, etc. You could be lucky you forced it through at all, but may have torn one of these rubber parts doing so.

If you are noticing an amount of raw water coming in, even with the thru hull closed, you may only be drawing from the loaded hose between the bowl and hull.

I hate to think you have a rebuild coming. Gotta do it sometime.


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post #5 of 13 Old 07-25-2012 Thread Starter
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Re: Head basics

Let me try that question again with more detail.

There is a Y valve that allow direct pump to overboard or pump to holding tank.
This Y valve is locked in the pump from toilet to tank position as required by law in the LIS.

There is a through hull lever for the inlet sea water.
There is a standard push pull type pump handle.
There is a switch that is labeled wet and dry. It can be set in either position.

With the through hull lever open and the switch set to wet it pulls water into the bowl and forces the water and the bowl contents to the holding tank as designed but some water is left in the bowl.
If the switch is set to dry and the handle is pumped the bowl contents are pumped to the holding tank and the bowl remains dry.

If however I do the following the bowl will not pump dry:
Open through hull
Pump wet
Close through hull
Pump dry. (There is back pressure and the the bowl will not pump dry)

If however I follow these steps instead it works perfectly:
Open through hull
Pump wet
Pump dry.
Close through hull

Notice that the only difference is that it seems as thought the through hull needs to be open in order to pump dry.

I'm just wondering if that is normal behavior?
I ask because it would be handy to leave the thru-hull closed all the time and flush the toilet with fresh water.
But since I have to open the thru-hull to pump dry this trick will not work.

As a side note the reason it was giving me trouble is that the tank was full. Apparently 4 people fill up the tank very fast. I went to a pump out to-nite and all is well.
I still have the behavior explained in the question however.

Last edited by davidpm; 07-25-2012 at 11:56 PM.
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post #6 of 13 Old 07-27-2012 Thread Starter
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Re: Head basics

I'm obviously making it more complicated than necessary.

Here is an another attempt at clarity.
If your head has water in it and the through hull for incoming water is closed can you pump the bowl dry to the waste tank?

I can't.
The head works perfectly fine when the through hull is open.
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post #7 of 13 Old 07-28-2012
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Re: Head basics

Mine (back when we had a real head) wouldn't pump easily or dry without the intake through hull being open. To pump dry with through hull open, I seem to remember a lever on the pump assembly needing to be switched.

It's been a year and half, and I could be wrong. It's what I remember though... hope it helps!
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post #8 of 13 Old 07-28-2012
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Re: Head basics

Quote:
Originally Posted by davidpm View Post
If your head has water in it and the through hull for incoming water is closed can you pump the bowl dry to the waste tank?

I can't.
The head works perfectly fine when the through hull is open.
That makes sense to me.

The pump has two parts: incoming water pumps into the bowl and bowl contents are separately pumped out. Most toilets have a handle and rod that connect to a disc that rides on an o-ring inside a cylinder. When in the dry position doesn't the intake side just move water in and out of the hose from thru-hull to the pump? If you close the thru-hull there is nowhere for that water to go, and water is an incompressible fluid.

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post #9 of 13 Old 07-29-2012 Thread Starter
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Re: Head basics

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Originally Posted by SVAuspicious View Post
That makes sense to me.

The pump has two parts: incoming water pumps into the bowl and bowl contents are separately pumped out. Most toilets have a handle and rod that connect to a disc that rides on an o-ring inside a cylinder. When in the dry position doesn't the intake side just move water in and out of the hose from thru-hull to the pump? If you close the thru-hull there is nowhere for that water to go, and water is an incompressible fluid.
That makes sense to me too but their are a couple of vents also and I sort of remember that you can pump dry if the thru-hull is closed on the last boat I was on.
So I'm thinking that maybe I have a clogged vent.
The head works fine however so I don't want to start taking it apart.
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post #10 of 13 Old 07-29-2012
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Re: Head basics

Quote:
Originally Posted by davidpm View Post
.....The head works fine however so I don't want to start taking it apart.
Amen
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