Black water level sensor always read full

[Rico K 2005 Knight]

Hi everyone. Rico K here. 

I was searching for help with my black water level sensors always reading full. I did find some good information on here that gave me an idea on how to correct the problem so I thought I would post my repair tactics. What I read was that it's most likely debris/toilet paper stuck to the sides and sensors. I eyeballed where the sensors are located in relation to the toilet ball drain and they line up very close. I removed the straight nozzle on my power washer and installed a tight 90 degree fitting and added the nozzle back on. Then I went down through the toilet drain and power washed the sensors and inside of the tank. Problem solved instantly. 

Just remember it must be a very tight 90 degree fitting or it won't go down the drain. Took me 2 attempts. Cheers.

Just to let everyone know. My problem with my warning beeper was my oil pressure sending unit. It was still reading proper pressure but being a VDO sensor it has 2 connections. 1 side of the sensor was bad.

Part #VDO 360 023

CHEERS.

[DavidL]

I use a jetter nozzle up the discharge line.  Modded a clear elbow that stays connected to the septic tank.  Put the jetter nozzle / hose through a hole I drill at the top side.  So you can see progress, drain the tank and get minimal blowback.

[Rico K 2005 Knight]

12 minutes ago, DavidL said:

I use a jetter nozzle up the discharge line.  Modded a clear elbow that stays connected to the septic tank.  Put the jetter nozzle / hose through a hole I drill at the top side.  So you can see progress, drain the tank and get minimal blowback.

That would great as well by the sounds of it. I just kept the drain valves open and had it pouring in a very large deep pan I made from a plastic drum. Progress was contained there lol. Used less than 5 gallons of water to get the job done then just poured it down the drain. What ever works for each individual I guess. We both have a working solution. 

[Tom Cherry]

These probes are nothing buy "Contacts".  The monitor is set to read a "Voltage".  Fecal matter and TP dry out.  Thus, when you dump a tank and back flush it, you get out most of it.  BUT, nothing is 100%.  The thin layer of "particulate" is like a wick. When you travel....water sloshes.  When you start to fill up a tank (any), then the capillary action of the water will start to creep upwards (being absorbed).  Once it gets closer to the first contact, the readings are "inconsistent" or at best...a JOKE or a LIE.  BTW....lest you think Monaco went cheap....they used the most conventional technology.  Municipal Waste Water Treatment plants measure the same way.  BUT, they have to put a 12" Plastic PVC or so pipe in.  They drop in SS rods of varying lengths....so when each rod (they get shorter of course at the top) start to "conduct" it displays as light or digital.  BUT, they have the SAME issue.  Crud gets on the SS probes (1/4 - 1/2 diameter).  The solution....they go to 600 V.  The HIGHER voltage then acts as a cleaner.  They "arc"....thus the crud is burned off.  I don't think that I could step up the 12 VDC to 200V and that the wiring would work....but it would arc and burn off any crud on the probe or the area around it.  YES...I have installed a BUNCH of commercial systems were we need very precise levels to start and stop pumps or sound alarms if a pump failed.  

The only solution is to clean and clean and clean and then use a good combo cleaner/odor preventer.  Many like, and it seems to work better for me, Happy Camper.  BUT, years of crud ain't going away.  There are all sort of methods out there and one can easily spend $50 to $100 on the "cleaners"....  and many use ice cubes as they drive to get a "scrubbing" action of the solid cubes on the interior side walls.  

The Pressure Washer wand sounds very ingenious.  What you have effectively done is remove the crud from the side walls.  There is no wicking, thus the sensors work better than before.  

Many folks have gone to a capacitance measuring system.  Think of an elevator button where you "TOUCH" it and it lights up.  The touching changes the capacitance of a small oscillator in a "transmitter" circuit....where the button is the antenna.  When that capacitance is changed, there is a relay or whatever that turns on.  The SeeLevel system is based on measuring the liquid using capacitance.  It works quite well.  HOWEVER, we have had many members that installed it and had to do several cleanings of the tank as the layer of crud was too great for the accuracy of the electronics in the SeeLevel.  Read the instructions and see what they say.  They "warn" against NOT using a good cleaner occassionally....as in if the layer (not said...but implied) gets too thick....it fakes out the system.

What will really be interesting is how long the cleaning lasts and how quick the crud builds back up.  I have tried about every conceivable method of cleaning as well as over zealous back flushing.  I just gave up.  I know how long it takes to build up.  I use a ratio of the Gray to Black.  When the Gray, without laundry...just dishes and showering, gets 3/4 or maybe 2/3, then I dump it.  The Black will barely be 1/4....so I don't sweat the Black and rely on the Gray.  

Since we do NOT boondock a lot....I don't worry.  I KNOW how much Fresh we have....and we can go up to 5 days, using restrooms as we are out of the CG.  So, that is my test.

BUT....the cleaning with a REAL pressure washer is novel.  Good Idea....  Let us know how long it lasts....

[96 EVO]

Yeah, let us know if it lasts!

I can get my lights out using the black tank flush, but, it doesn't last long.

[Rico K 2005 Knight]

3 hours ago, Tom Cherry said:

These probes are nothing buy "Contacts".  The monitor is set to read a "Voltage".  Fecal matter and TP dry out.  Thus, when you dump a tank and back flush it, you get out most of it.  BUT, nothing is 100%.  The thin layer of "particulate" is like a wick. When you travel....water sloshes.  When you start to fill up a tank (any), then the capillary action of the water will start to creep upwards (being absorbed).  Once it gets closer to the first contact, the readings are "inconsistent" or at best...a JOKE or a LIE.  BTW....lest you think Monaco went cheap....they used the most conventional technology.  Municipal Waste Water Treatment plants measure the same way.  BUT, they have to put a 12" Plastic PVC or so pipe in.  They drop in SS rods of varying lengths....so when each rod (they get shorter of course at the top) start to "conduct" it displays as light or digital.  BUT, they have the SAME issue.  Crud gets on the SS probes (1/4 - 1/2 diameter).  The solution....they go to 600 V.  The HIGHER voltage then acts as a cleaner.  They "arc"....thus the crud is burned off.  I don't think that I could step up the 12 VDC to 200V and that the wiring would work....but it would arc and burn off any crud on the probe or the area around it.  YES...I have installed a BUNCH of commercial systems were we need very precise levels to start and stop pumps or sound alarms if a pump failed.  

The only solution is to clean and clean and clean and then use a good combo cleaner/odor preventer.  Many like, and it seems to work better for me, Happy Camper.  BUT, years of crud ain't going away.  There are all sort of methods out there and one can easily spend $50 to $100 on the "cleaners"....  and many use ice cubes as they drive to get a "scrubbing" action of the solid cubes on the interior side walls.  

The Pressure Washer wand sounds very ingenious.  What you have effectively done is remove the crud from the side walls.  There is no wicking, thus the sensors work better than before.  

Many folks have gone to a capacitance measuring system.  Think of an elevator button where you "TOUCH" it and it lights up.  The touching changes the capacitance of a small oscillator in a "transmitter" circuit....where the button is the antenna.  When that capacitance is changed, there is a relay or whatever that turns on.  The SeeLevel system is based on measuring the liquid using capacitance.  It works quite well.  HOWEVER, we have had many members that installed it and had to do several cleanings of the tank as the layer of crud was too great for the accuracy of the electronics in the SeeLevel.  Read the instructions and see what they say.  They "warn" against NOT using a good cleaner occassionally....as in if the layer (not said...but implied) gets too thick....it fakes out the system.

What will really be interesting is how long the cleaning lasts and how quick the crud builds back up.  I have tried about every conceivable method of cleaning as well as over zealous back flushing.  I just gave up.  I know how long it takes to build up.  I use a ratio of the Gray to Black.  When the Gray, without laundry...just dishes and showering, gets 3/4 or maybe 2/3, then I dump it.  The Black will barely be 1/4....so I don't sweat the Black and rely on the Gray.  

Since we do NOT boondock a lot....I don't worry.  I KNOW how much Fresh we have....and we can go up to 5 days, using restrooms as we are out of the CG.  So, that is my test.

BUT....the cleaning with a REAL pressure washer is novel.  Good Idea....  Let us know how long it lasts....

I will update on how it works out. No problem on doing now and then when needed. Nothing to dismantle. Just hold the toilet peddle down and spray the wand back and forth. Took less than 2 minutes of cleaning after the setup. Now I have the adapter so next time will be easy.

[96 EVO]

Yeah, it's just if it only works till next time you fill the black tank, it's not really worth the trouble!

Like Tom, I go by days. Another thing, when my tank (and others), get's near full, it kinda burps when you flush the toilet. That let's me know, it's definitely time to dump!

[1nolaguy]

7 hours ago, Rico K 2005 Knight said:

Hi everyone. Rico K here. 

I was searching for help with my black water level sensors always reading full. I did find some good information on here that gave me an idea on how to correct the problem so I thought I would post my repair tactics. What I read was that it's most likely debris/toilet paper stuck to the sides and sensors. I eyeballed where the sensors are located in relation to the toilet ball drain and they line up very close. I removed the straight nozzle on my power washer and installed a tight 90 degree fitting and added the nozzle back on. Then I went down through the toilet drain and power washed the sensors and inside of the tank. Problem solved instantly. 

Just remember it must be a very tight 90 degree fitting or it won't go down the drain. Took me 2 attempts. Cheers.

Just to let everyone know. My problem with my warning beeper was my oil pressure sending unit. It was still reading proper pressure but being a VDO sensor it has 2 connections. 1 side of the sensor was bad.

Part #VDO 360 023

CHEERS.

Just out of curiosity Rico What size fitting did you use (ie: Male to female 3/8" FPT) and what size spray nozzle? I am concerned anything tighter than 18deg spray might damage the walls of the tank.

[Rico K 2005 Knight]

6 hours ago, 1nolaguy said:

Just out of curiosity Rico What size fitting did you use (ie: Male to female 3/8" FPT) and what size spray nozzle? I am concerned anything tighter than 18deg spray might damage the walls of the tank.

3/8 FPT with a very tight 90 degree brass fitting and a 45 degree tip nozzle. No damage at all.

[1nolaguy]

Thanks! I believe that is a standard size for US pressure washers so what fit your will most likely fit others.