Black tank levels

Gary the Wombat · 03-08-2007, 07:10 AM

Our black tank level on the panel now shows 2 thirds full when it is in fact empty, then shows full after it has been used for a couple of days. Anyone have any clues why? Is this something I can adjust myself? This only started recently--it used to show correctly. I understand that there is some kind of rheostat adjustment behind the panel. Would this help? Thanks.

Gary the Wombat · 03-08-2007, 07:10 AM

Our black tank level on the panel now shows 2 thirds full when it is in fact empty, then shows full after it has been used for a couple of days. Anyone have any clues why? Is this something I can adjust myself? This only started recently--it used to show correctly. I understand that there is some kind of rheostat adjustment behind the panel. Would this help? Thanks.

dirko · 03-08-2007, 07:29 AM

Hi Ho: Your problem is usual. The way most tanks work is that there are metalic sensors that determine if water is behing them. The problem is that they get wet and get stuff on them that makes them act like there is water there when it really isn't. Cleaning the tank is a possibility, and there are a myriad of methods that can be used. If you really don't like the "look down the toilet" method there are aftermarket sensors that have more resolution and are more foolproof than the OEM sensors do.
Good luck.

John Hilley · 03-08-2007, 07:29 AM

The sensors are probably dirty. There are some products available to clean them and flushing the tank will help.

John_Canfield · 03-08-2007, 07:53 AM

The sensors are on the outside of the tank (at least ours are) but grunk can get built up and coat the inside of the tank and cause false readings.

You should not dump your tanks until they are pretty full to minimize this happening. Of course we don't follow our own advice and usually leave the gray valve open when parked for a couple of days or more. Our gray tank has read 1/3 full for the last several months even when empty and just recently it correctly read empty.

I really don't know if there is an adjustment for their sensitivy or not - I'd give Winnebago customer service a call and ask them.

ISLAPP · 03-08-2007, 08:23 AM

John is correct. You no longer have the kind of sensors that used to protrude thru the side of the tank. Winnebago claims these are supposed to be much more accurate than the old style. Looks like maybe that ain't the case. There used to be individual adjustments on the back of the main panel for each tank. But I would check with your dealer or Winnebago before removing the panel to see if they still use them. If they do, they can explain where they are and how to adjust them. Otherwise, what might be wrong is there is probably an orange resistor wired to the sensors on the outside of the tank. If that resistor goes bad, you will get a false reading.
Mike

Y-Guy · 03-08-2007, 08:24 AM

Pretty sure we have the sensors on the outside as well. You might try to fill about 1/2 full, then dump ice into the tank and drive around. Does a good job of dislodging stuff stuck to the sides. Also adding some Calgon Water Softner to a tank of water helps as it coats the sides and makes them nice and slick. I'm sure this has been talked about on here, search for Calgon should bring up some more on the subject.

AFChap · 03-08-2007, 08:57 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">some kind of rheostat adjustment behind the panel. Would this help? </div></BLOCKQUOTE>
Gary

It is true that then sensors can get crudded up. However, adjusting the little "pot" screws may help. It is worth a try. What I found on mine is that the sensor board in the basement water compartment has the adjustment pots, but I didn't find them on the board inside. Adjusting those outside (adjusting them to read empty just after I dumped the tanks) did help for them, but didn't do anything for the ones inside that are so much easier to monitor.

Gary D · 03-08-2007, 01:28 PM

Comments on tank monitoring from a new member and first post.

I recently installed a SeaLevel II tank monitoring system in the service bay. It measures all tank levels in percentage. In addition it measures battery voltage and LPG level as a percentage of full. Although a bit of a challenge to install I can now monitor tank levels while filling and emptying the tanks.

I have also installed a Trik-L-Start with a 110 watt solar panel to keep chassis battery up to snuff, a Roadmaster Even-Braking System and a Protect-a-Tow for the Honda Civic toad.

Now just waiting for the weather to improve to hit the road.

Gary D

2007 Adventurer 35A
Honda Civic

[email protected]

ISLAPP · 03-08-2007, 03:39 PM

Welcome Gary D. I also have the sealevel and think it is a very good system.
Again, welcome.
Mike

Clay L · 03-09-2007, 05:56 AM

Since Winnebago went to the non contact sensors in 2005, the new circuit boards do not have an adjustment on the waste tanks.
There is one on the LP tank since it still uses the old potentiometer style sensor.

There is no adjustment because the sensors on the tank are either on or off. They are active - that is, there is circuitry in the square black sensors on the side of the tank that turns on when it sees liquid (or enough crud on the tank wall). As each one turns on, in effect it shorts a resistor which causes the voltage being sensed to decrease and this is detected.

I used a pressure washer to clean the inside of my black water tank and it worked fine for a few tank fulls. Then the 1/3 level LED started staying on. I started adding a half cup of liquid Tide to the tank each time I emptied it and the 2/3 and full LEDs have continued to work – for about six months so far. I also add Tide to the grey tank when we travel along with a few gallons on water.

I spoke or had email contact with most of the manufacturers of non-contact level sensing systems and most indicated that it was possible to have enough crud on the tank walls to fool their systems.
The one that says theirs is foolproof uses pressure sensors that can be mounted on the top of the outlet lines from the tanks.

kenbt · 03-15-2007, 11:34 AM

Here is one I cannot figure out...On my 2005 Vectra I have the exterior sensing devices...the instrument pannel on the inside of the coach says my grey tank is empty but the outside moniter pannel in the plumbing area say the grey tank is 1/3 full. I would think they both use the same sensors so why would they read different?

Ding-a-ling · 03-15-2007, 04:58 PM

Just wondering - does no one else use the San-T-Flush connection to clean out the black tank? When I set up in a CG I run a fresh water hose for drinking water and an old green hose to the flush connector. When I dump I ALWAYS run the flush on the black tank for a minimun of five minutes. My tank level gauges always read correctly, and always read Empty after dumping.

John_Canfield · 03-16-2007, 04:54 AM

We also flush the black tank virtually every time we dump and it has always read properly. I wish the gray tank had a flush connector.

Ken - our inside/outside monitor tank levels always track together. Don't know why yours would be different.

AFChap · 03-16-2007, 06:54 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">does no one else use the San-T-Flush connection </div></BLOCKQUOTE>
I always flush the black tank liberally when dumping. My inside sensor panel readings have always been a little different from the outside panel readings, with the black being less than actual. Since a close lightning strike in January, the inside readings on the black tank always read full.