New Tank Sensors!

Tanks Sensor Replacement

Failing Tank Sensors/Monitor on our 2008 Winnebago 39Z

Our tank sensors have gone from occasional faulty readings to hard failures about 80% of the time.  We first had problems not long after purchasing Lola from La Mesa RV in Davis, California.  But the problem was intermittent and Le Mesa said it was tank sludge build-up on the sides.  In the past couple of years the failure changed to ALL the tank lights (water, black and the two grey tanks) being half-bright; all at the same time.  We tried various tank cleaners with no help.  Now, this seems to us that all lights being half-lit regardless of the content level to be strange behavior – not what we would expect if the tank sludge was building up.  We last took Lola into La Mesa last fall, and the half-lit lights were displaying so we could show the service advisor.

La Mesa – Big FAIL

I couldn’t believe when he said it was probably sludge build-up inside the tanks.  But, how could that effect ALL tank sensors at exactly the same time?  Consistently?  It seems to me it’s probably the wiring or more likely the display unit.  When we picked Lola up after being with La Mesa for a MONTH, the service advisor said it was probably sludge in the tanks and the service technician put some ‘stuff’ in the tanks to help clean them out, and the extended warranty would not cover an intermittent problem (even though we showed it not working when we came in).  This is not the first time that Davis La Mesa has not put forth the effort to correctly troubleshoot problems for us.

This last winter we lived in and out of Lola while remodeling a house and did not have the opportunity to fully check out our sensors until going to Lake Mindon in May.  Once we started using the tanks what happened?   You guessed it, ALL sensor lights are half lit again.  Once in a while the sensors will show the correct levels.  If you are attached to full hookups all the time, then not having sensors on the tanks is not a real big issue since you are connected.  But, when you are dry camping or boondocking it is more important to keep track of your fresh and waste levels.  And here at Thousand Trails Lake Minden we have no sewer hookups.

Sensor Replacement

We have been looking at Garnet Industries SeeLevel systems for quite some time.  They are a nice upgrade to the standard 1/3, 2/3, FULL in our Lola by giving percentage increments at more frequent intervals.  They have also received good reviews from many sources.   Depending on the tank size and number/length of sensors installed the percentage increments could be 5% or 8% more or less.  We looked at getting new sensors at the FMCA rally we attended in 2016, but the problem was intermittent and the pricing was fairly expensive for our budget since we had other upgrades we were doing at the time.   Since we are doing more dry camping and boondocking now we decided to upgrade the sensors at the next opportunity.

Many RVers live with bad tank sensors.  For weekenders or vacationers it is probably a minor inconvenience.  For full-timers and those who really rely on knowing their tank levels it is more important.  Also for those folks like us who like things to work correctly it’s more than a minor irritance.  We like things to work!

Garnet Industries at the FMCA Rally

Yellowstone was our number one objective this summer, and it so happens that the FMCA Rally is in Gillette, Wyoming – just across the state from Yellowstone.  Not only that, but Garnet Industries is at the Rally.   After a call to Garnet we contacted the installer and scheduled an installation for the Monday before the Rally (first events are Wednesday).   We also signed up for a tank clean-out on Tuesday just to cover all the bases.  We registered early for the Rally to get full hookups in case it is warm and we need to use the A/C for the dogs while we are out.  That worked well with the tank clean-out because he needs sewer hookup for the flushing process.

Our Capacities

An interesting side-note is that our spec sheet gave us capacities for the Fresh and Black tanks, and only one capacity for the Grey tank – but we have two grey tanks; a galley tank and a shower tank (that the washer also drains into).  So I called Winnebago to find out the capacity of the two grey tanks.  I was told that the galley tank was 20 gallons, and the big grey tank is 52 gallons – that matches the 72 gallon grey capacity in the owner manual.  However, the black tank is 48 gallons – not the 62 gallons listed in the owners manual because of a mid-year production change.
[When I actually drained the galley tank after installing the sensors I took out 27 gallons of grey water (just reached the 100% sensor indicator!]

2008 Winnebago 39Z Specifications Vs. Corrected
92 92
62 48
Main Grey
Unknown 52
Unknown 20 27+

Sensor Installation Planning

We arrived in Gillette on Sunday and after a bit of confusion got parked in our full hook-up section.  Gene Riffel of Ruffnit RV stopped by as scheduled at 9.  After explaining the process he went through and checked out the configuration of our tanks and the sensor display.  We originally wanted to install the bluetooth version thinking that the installation would be easier (cheaper) plus would give us the capability to monitor the tank levels outside while filling the fresh water or dumping.  However the bluetooth model does not support 4 tanks at this time, so we went with 2 monitor installations – one inside and one outside in the water/sewer bay.  We also elected to keep the old sensor display for the LP meter and place the new SeeLevel monitor to the side of the existing control panels.

Our tanks were partially full and we did not dump on purpose so the new sensors could be tested with tanks that have content.

Locate The Tanks

Fresh Water Tank

Our fresh water tank is enclosed in a steel shell.  Towards the front where the overflow exits the tank there is an access panel.  Once the panel is removed easy access to the tank allows Gene to install the new sensors.

Fresh Water Tank
Fresh Water Tank Under Floor

Main Grey Tank and Black Tank

To access the main grey tank and the black tank the access panel above the tank gates in the water/sewer bay needs to be removed.  Once that is put aside, there is very tight access to the sides of the grey tank (on the left) and black tank (center).  Here, another decision point came into play.  Neither of these tanks are square!  They have a drop-down section that Gene estimated to be around 3 or 4 gallons; plus there is a seam.  Option 1 is to put 2 sensor strips in.  One above the seam and one below.  The second option would be to leave the lower drop-down section without a sensor.  We decided to leave the lower portion of the tank without a sensor and cover the upper section.  The savings of not getting another package of sensors covers a portion of the cost of the second monitor.

Main Grey And Black Tank Locations
Main Grey and Black Tank Locations

Galley Tank

Access to the galley tank is through the main power bay (where the power cord and inverter etc. is).  The tank is installed at a slight incline, so the sensor can’t be placed where it will be 100% accurate.  Again, we tried to get the top portion of the tank metered.  [We checked this out while dry camping the next month and found that when the first indication above 0% (which is 8%) first lit up we drained an 11 gallons.  This gave us a gauge covering gallons 12-27 which is the most important range for us, but were surprised it did not cover more.]

Verify Electrical

Especially because we are having problems with our existing sensors, Gene verified the wiring – especially the ground.  Wiring and ground check out good for each of the lines!   It’s always good to not uncover additional issues to solve, which seems to be our ‘luck’ often enough.

Verify Sensor capability

One issue Gene has seen with Winnebago RVs is that some tanks can be thicker than used with other RVs.  Winnebago builds their own tanks.  He tested the sensor’s sensitivity by using a test unit on the tanks, and a test meter inside.  This double checked the wiring and checked that the sensors should work… before doing all the work of installing sensors then finding out that they won’t work.  According to Gene, Garnet uses some of the most sensitive sensors on the market so he rarely finds a problem.  Once attached, the sensor worked fine and indicated the level in the tank.  Being a sensitive type of guy, this was important to me too!

2018-07-16-1031-32-SeeLevel II Sensor Install
Test Sensor


Sensor Installation

Once the tank locations are found, access panels opened and sensor locations & options are identified Gene went back to his shop for a break and to gather additional parts (i.e. the second meter package that included more sensors and the meter for the outside bay).  When he got back he installed the sensors – verifying each installation with his test monitor in the coach.

Meters Installation

Inside Meter

Once the sensors were installed work went back to the inside to wire and place the SeeLevel meter.  Again, since we are keeping the existing tank monitors for LP the SeeLevel meter was placed to the side of the Winnebago control station. Gene confirmed with Christine exactly the height of the SeeLevel meter.  Good thinking!  Always check with the boss for the important items ;-).  A new hole is cut beside the panel in the wall and the SeeLevel set in place.  No issues getting the inside meter running and installed.

Outside Meter

For Jeff, the outside meter is the most important.  Fresh water tank filling is a slow process when using the pressure regulator, and it’s nice to have a meter outside.  It is also convenient when manually dumping the grey water into a bucket when dry camping [a lot of campgrounds offer grey water dumps], or just checking how far along you are when at a dump station.  Like the inside meter, hooking up the meter went fine.  After checking that the outside meter worked, Gene disconnected the meter for the access panel replacement.

Sensor Wrap UP

Now that all the sensors are installed and the meters are working it’s time to close everything up.  The fresh water access panel is screwed back into place.  The challenge is getting the access panel in the water/sewer bay put back.  Besides working by feel only getting the short screws lined up with the spring/gromet screw holders was a real pain in the bazooka.  It took a lot of patience and time to get the panel installed correctly.  It might have been easier to reverse the screw and go from the other side but Gene didn’t want a screw point showing through the panel.  He wanted it done right!   With the panel in place, the outsider meter is permanently attached.

One last check, and we were presented with the bill.

We were quoted $225 for 4 tanks and 1 sensor plus installation at $85/hr.  Garnet has not changed their hourly installation rate in several years, so this is a good price.


Tanks Wash-Out

In our phone conversations with Gene for the sensor installation he let us know that some Winnebagos that have thicker wall tank construction could show issues when sludge build-up occured.  To be on the safe side, we elected to have our tanks washed out – pretty sure it’s the first time Lola was given an enema.  Plus we wanted to see if La Mesa was correct about sludge build-up.

John Michel from All Pro Water Flow is an approved vendor through FMCA at the Gillette Rally.  All Pro Water Flow has independent service professionals all over the U.S. (and Canada?)  URL.  John arrived exactly on time on Tuesday afternoon to power wash Lola’s tanks.  John had warned us when we scheduled a month earlier that timing was dependent on weather.  He did not work outside during lighting storms.

With thunder storms approaching and lighting on the horizon John started work.  Power washing took just over 90 minutes.  John did get some sediment, mostly on the bottom of the black tank and some more on the bottom of the galley tank.  A good wash getting some sludge, but probably not enough to effect the sensors.  After giving us a recipie to help keep the sediment from collecting in the tanks and rolling up his hoses he was off to home just as the thunder started booming over us and big raindrops started dropping.

The cost?  $220.00.  Not cheap, but another of those maintenance items.  For stationary RVs John recommends an annual flush, however if your are traveling on the road a flush every couple of years is sufficient.

Here’s John’s recipe for keeping sludge build-up to a minimum:

“Recipe” for the All Pro Water Flow Tank Solution

Mix up a gallon of this solution to use in both your black and gray tanks while you are RVing. It will keep the internal surfaces of your RV’s holding tanks slippery (reduces build-up), sanitizes the tanks, and has a nice, fresh smell.

  1. Start with an empty gallon jug
  2. Pour 1/4 cup (4 ounces) of Calgon Bath Beads (or liquid) into the gallon jug
  3. Fill the jug 1/2 full with water. Shake well.
  4. Slowly pour 40 ounces of Pine-Sol into the jug. Shake well.
  5. Top off the gallon jug with water. Shake well.

Use 8 ounces (one cup) in your black tank(s) and 4 ounces (1/2 cup) in your gray tank(s) each time, after emptying and backflushing.

Bottom Line

La Mesa – Davis

Most likely our tank display was faulty.  It is clear that La Mesa did very little troubleshooting on the issue.  If we had a spare meter we could have done the diagnosis for La Mesa, however since we wanted (needed) an upgrade over the stock Winnebago gauges I wont’ go down that hole.  La Mesa had our RV for a month and did not fix our washer (washer and dryer did not work – hard failure) nor our tank issue (another problem that was showing failure at the time we brought it in).  They did fix our chassis A/C issue – but that failed again the next time we used the chassis A/C (this is the second time La Mesa ‘fixed’ our chassis A/C).  This is the last time we will bring in our RV to La Mesa in Davis.

A Month Later…

Update after using the new sensors for a month.  Wow!  For us this is a great improvement.  We have had no issues with faulty readings.  It has been a good choice to have the ‘top’ of the tanks covered and the bottom notch-out not for the main grey and black tanks.  We have done 3 weeks of camping without sewer hookups – 2 with grey water disposal locations close enough we could empty our dish water into a bucket from our outside bay.  That is the tank that fills up fastest.   It was here that we found out that our grey water tank holds at least 27 gallons.  We emptied the tank when it first showed 100% and it had a little more room at the top.  Gee, I wonder how much the main grey tank holds?  I’m not manually emptying that tank just to find out!  If someone else has a 2008 Winnebago 39Z and manually checks the tank capacity, let us know.

Hope you have found this (long, technical) blog interesting, let us know that too!

Happy Trails and See You On The Road

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Jeff and Christine

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