jkill2001 wrote: my sensors in my black tank keep playing games with me. they have been recently replaced and i know for 100 percent sure i have nothing in the tank but they will still read 2/3 but sometimes they will read 1/3 and now tonight they read empty. anyone ever seen or heard of anything like this and anything i could do about it. the mh is a 2003 winnebago adventurer
As others have said, this, my friend, is an on-going battle for most RVers.
I had a problem with my gray tank similar to your problem. I solved it by filling the tank with water, tossing in a bottle of gray tank cleaner (Thetford?) and a jug of Simple Green and let it eat for a few hot summer weeks out in my driveway. I dumped it the next time we went out. It ate the******off of the sidewalls of the tank enough so the sensors worked correctly. This was not a factory suggested formula or a "recipe handed down through the years". It was one that was carefully crafted after about 30 seconds of scanning the shelf where the cleaning supplies were kept. You are free to experiment and develop your own tried and true concoction. After all, it's a plastic tank, what can you reasonably do to hurt it.
I don't know what year Winnebago switched over to the TrueLevel tank sensors, but they are more reliable then the sensors that poke through the tank side wall into tank, and are easier to restore to operation. You may wish to switch your sensors over to this kind, or some equivalent system. They just glue to the outside of the tank.
Once (and if) you get them running again, you can chuck a cup of powdered laundry soap and a cup of water softener stuff in the tank after you empty it, so that it will help clean the tank as it fills. The soap does what ever soap does, and the water softener stuff makes the tank wall a little slick so the******doesn't adhere to it.
Or you can just give up and peek down into the tank once in a while and rely on windage and engineering judgment as to when the tank needs emptying.
Dave & Mary
Isabel (a cuddly little Boston)
Buddy (The Beast) another Boston
2005 Itasca Suncruiser 35A
2003 Jeep Liberty
If it's listed in the Yellow Pages, the government shouldn't be messing around with it.
I too had the same problems. I found a recipe online that included bleach and water softener. I put that in with a few gallons of water, drove to my destination, allowing it to slosh around and rinse the walls of the holding tanks (I did it in black and gray tanks). When I drained them and washed them (tornado), it had dissolved everything on the walls and cleaned the sensors. It takes about 10-15 minutes after draining for them to show empty. I guess drying time. I do this maybe 1 time a year and it seems to work. Hope this helps
Todd, Kris (wife), Jarrett (7 yo son), Emily (4 yo daughter), and usually Jim and Dee (the in-laws.)
We've had our Cross Country for almost 5 years and never had any problems with the sensors reading correctly.
This is what has worked for me all these years. It's simple - I just add some laundry detergent to each tank before leaving for home. When I get home I dump both tanks. I've never flushed the tanks with anything - just use the detergent and my sensors have been working great for years.
jkill2001 wrote: my sensors in my black tank keep playing games with me. they have been recently replaced and i know for 100 percent sure i have nothing in the tank but they will still read 2/3 but sometimes they will read 1/3 and now tonight they read empty. anyone ever seen or heard of anything like this and anything i could do about it. the mh is a 2003 winnebago adventurer
Replacing the sensors was not the answer because dirty sensors will cause read empty readings not full ones.
If it's made by Ventline as many are, there is a 68k ohm resistor between the full and 2/3 sensor and one from the 2/3 sensor to the 1/3 sensor. The wire from the panel connects to the full sensor. On some units the resistors are potted in a small plastic cap close by the tank with one wire leading from it back to the panel. There is another wire from the ground sensor also going back to the panel.
On others all four wires go into the wiring harness and I don't know where the resistors are located. Maybe on the display panel?
The display panel has five "LM339 Low Power Low Offset Voltage Quad Comparator" ICs (one for each waste tank, one for the propane tank, the water tank and one for the battery voltage) that are used to sense the voltage drops across the sensors and activate the proper LED.
The problem is that fluid holding crud builds up on the tank walls and that fools the sensors into thinking there is fluid in the tank.
The non-contact sensors are better but not foolproof either. According to their web site the SeeLevel system can also be fooled but at least it just stops giving a reading rather than showing a false one. That is your signal to clean the tank walls.
I have the TrueLevel non-contact system that Winnebago went standard with in 2005 (right after I bought mine of course) and right now my black tank reads full all the time but the top two LEDS of my gray level is accurate.
I have pressure washed the black tank wall twice and it worked okay for a while. I added a cap of liquid Tide to the tanks when we traveled and it keeps the gray pretty clean but not the black.
I suspect that as full timers the use is heavy enough that it is difficult to keep the tank wall clean. Also I am not sure I can do a good job of cleaning the side of the tank where the sensors read through the wall.
I am considering paying the $150 dollars or so to have the tanks pressure washed by a company in AZ that uses a pressure washer threaded up through the sewer outlet. They use a video camera to make sure the walls are very clean.
My hope is that if I start with clean tanks and add the detergent each time I empty that the readings will be accurate.
Clay (WA5NMR), Lee,(Wife) Codi, Brandi (Shelties) and Damncat (damn cat)
Full Timing in a 2004 Winnebago Sightseer 35N, Workhorse chassis, Honda Accord toad
Have a NRV Tradewinds with the same problem. Bought it New and the indicators were ok until a month ago. Have only put 6K on it. The warranty is no good because National shut it's doors. But would like to find a solution for this problem.
The nice things about the SeeLevel system are that they work, you actually get percentage of full reading for all tanks (including propane), house battery reading in 2 decimal point voltage and they are easy to install because you can use the existing wiring (if you can get to your tanks to mount the sensors). They are a little expensive but you'll get appropriate readings.
Dave
Plus New Brunswick, Prince Edward Island & Nova Scotia
Offline
and rely on windage and engineering judgment as to when the tank needs emptying.
& Mary 
