22 May - NSTR RV Maintenance Day, Laundry

 Down day here today.  No touring and no shopping.  Doreen did several loads of laundry in preparation for our departure on Monday while I worked on the RV.  Later, we headed down to the beach and watched the speed boats preparing for their race this weekend.  The Atlantic was still pretty angry which has stirred up the seaweed which is covering the beaches.  A couple stopped over and was interested in our Alliance RV so we gave them a tour.  We facetime'd with our son Dan because tomorrow is our grandson Calvin's birthday.  They were celebrating at a Mexican restaurant and Calvin was wearing a huge sombrero!  If you are interested in my RV repair project, read on.  If not, punch out now, as fast as you can!!  That's about it for today! 

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More than you ever wanted to know about RV sewage tank sensors:

Disclaimer:  If you decide to do this, make sure your tanks are empty and no one uses the toilet, sink, shower or washing machine while you are changing sensors or you will have a mess on your hands, literally!!  Also, this mod/upgrade, like any other mod/upgrade, is done at your own risk, pertaining to your warranty.  

The RV toilet is connected to a black sewage tank.  The kitchen and bathroom sinks are connected to one of the grey tanks and the shower (and washing machine if you have one) is connected to the other grey tank.  There is a display inside the RV that shows how full your tanks are.

Our black and grey tank sensors have been giving false reading which usually means they are dirty/contaminated with soap scum, toilet paper, etc.  It is a common problem with RV's.  Usually most people just give up on using them as an indicator and just dump every so many days.  Sorry, not me!  There is an alternate sensor available and I upgraded our previous 5th wheel and never had another issue, so today is the day for the Alliance.  We are on a paved site, the weather is great and I have a little spare time today.

The matter is complicated on the Alliance since the "underbelly" of the RV, made of a corrugated plastic material called "Coroplast", is riveted on.  The Jayco underbelly could be unbolted and removed which allowed fairly easy access to the sensors.  So months ago I did a Facetime video/audio call with one of our points of contact in the Alliance factory, and we took some measurements to determine where to cut access panels in the underbelly material.  I also ordered the newer style, more reliable sensors but until now I have not had an opportunity to install them.  

Here is a picture we took while we toured the Alliance plant last summer.  Obviously this is taken from the top side which is inaccessible on a completed coach, but it does show the sensors in relation to the tank. The colored wires are connected to the sensors.

The OEM sensors look like this.  They are simply a metal button on the end of a bolt.  They are inserted into the tank at prescribed heights so as to detect liquids at specific intervals:  Empty, 1/3, 2/3, and full.  The nut is tightened down which compresses the rubber and locks them into the tank.  The wires coming from the display are connected through a resistive bridge to these sensors.  As the liquid inside the tank touches the metal sensor it allows current to flow which results in a display of the appropriate tank level.  

Soap scum, toilet paper and other contaminants can build up on the sensor and give false readings. The black tank has a sprayer inside which helps keep the sensors clean, but the grey tanks don't have a sprayer.  In our case it was primarily the grey tank connected to the shower that was displaying inaccurately.  The black tank sensors were also giving us problems.  Here is a clean sensor and a couple contaminated sensors that I removed today:

A fairly clean sensor

Contaminated sensor

Soap scum on this sensor

The newer style sensors look a lot different.

New style grey tank sensors

New style black tank sensors

The primary difference you can see is rather than a metal button, the new sensors use a Teflon coated pin with just the tip exposed.  The newer style blank tank sensors also have a plastic shroud over them to keep toilet paper from fouling them.

So now we needed to cut an access hole in the Coroplast underbelly to give me access to the sensors so I could replace them.  The measurements worked, and we nailed the first one, which was Grey 1.

Cut three sides so I can hinge it out of the way and re-close it when done

Bottom view of the four sensors on Grey 1 tank

The first sensor removed

The first new sensor being installed

And that is about it.  I completed Grey 1 and Black 1.  Grey 2 is behaving itself for now.  It is going to be a multi-hour job to change those sensors as they are really buried.