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Automatic Water Fill Valve

On some coaches is a cool feature that allows you to flip one switch and fill your tank if you are connected to city water.  

If it works, it’s great!  But if it doesn’t work, it causes really weird problems.

The way that it works is that there is a cutoff valve is in the main water line after the pumps (12V and 120V).  When activated, it diverts pretty much all the water into the top of the tank.

It is made by Asco. (Model 104R Shutoff valve)  


The bad news is that the valve is prone to getting gunk’d up and stopping working.  More on that later.

The good news is that it is really old school and designed to be cleaned and repaired.  

To clean it, pop off the red cap.  Now here is the tricky part.  Depress the entire green housing.  That will allow the metal title plate to slide over and come off.  (The plate is what holds the housing to the piece with the center post).  Be sure to catch the spring at the base of the center post.  (See picture).


Once you have the housing off, you can remove the four bolts.  The center post and its base will come off now.  (There is a rubber diaphragm under the base).   You will find a plunger/spring under the diaphragm.  Clean it all up.  You will find a tiny hole in the diaphragm.  Make sure this is clean as well.  

Put it all back together including the springs.  NOTE:  the tiny hole need to be oriented 45 degrees away from the outlet. 


1).  Low water pressure inside the coach no matter what you do.  City/Tank/12V pump/120V pump it doesnt matter.  You might have a little flow but not much.
2).  If you are connected to city water long enough, your tank will fill and will finally overflow.   This will create a big watery mess.  (Ask me how I know this).
3). The pumps will not develop enough pressure to cut off...even if you have no water running inside the coach.

The failure mode seems to be that the plunger gets stuck.  The diverts water into the tank even if you don’t want it to.

So in the words of an elder guru. ... “Think horses not zebras”.  I had already replaced my 12V pump thinking it was leaking air into the system and would not prime.  What was really happening is that the pump was working correctly but pumping water into the tank.  The clue that I should have paid attention to is that both pumps stopped working at the same time.  Also, the water tank overflowing was a well-duh moment.

If you have one of these valves, add an annual cleaning to your PM list.

Bill Johnson
2003 Newell #653 Quad Slide Cat C-12 engine with Motorcycle lift 
2011 Jeep Wrangler, 2018 BMW 1200GS Adventure Motorcycle
Auburn, Alabama

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Automatic Water Fill Valve - by bikestuff - 01-10-2019, 04:26 PM

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