Black water gauge stuck on 2/3rds

[Wanabee FTer]

Just came back from a long shake down cruise. I found a few problems, one of which is the black water tank gauge will not show below 2/3rds full. I tried adding calgon water softner and laundry soap a few different times while driving. The black water seems to come out quite clear after I flush it out. I bought a clear drain adapter with a hose connection, but did not try the hose flush because there is a bend in the line between the adapter and the tank.
Is there anything else I should try before going any further?

[RV Wizard]

If you can access the tank monitoring sensors, remove the lower connections and check the monitor. If it does not change then the problem is probably the resistor pack at the sensors. If it does change then the sensors are contaminated.

[RickO]

Most of these gages are notorious for getting contaminated and giving inaccurate readings. My coach is only three years old and the grey tank and fresh water gages are doing the same thing.

My plan is to replace them all with See-Level gages which have sensors on the outside of the tanks... but, that's just on my list of things to do.

[Paul R. Haller]

Before you drive the thing again use the fabric softener and soap routine but add a bag of ice to the toilet with enough water to slosh around. That will usually do it with a 1/2 hour drive.
-Paul R. Haller-

[Wanabee FTer]

Wow, after hearing about a 3 year old rig with gray water gauge problems I feel lucky my gray water gauge is operating properly.
I bought a water nozzle wand today at the local RV store. It has a single side spray nozzle that I am going to direct at the sensors. If that doesn't work, maybe sloshing ice in tank with calgon and laundry detergent?
Then I have to decide if I really want to go for the next step, sensors or possible resistor?

[Batman_777]

Check your sensors for outside the tank stick-on pads. If you have a stick-on sensor, there are several posts with discussions about them. They are notorious for being sensitive to RF interference and giving false readings after the tank has a build-up on the inside wall.

Concerning RF noise, have you added anything lately that generates RF?

The stick-on pads are very easy to replace.

Stick-on pads are easy to locate. Just look for them at the end of the tanks. They are rectangle about 2x3 inches and about 1/8 of an inch thick. They stick on the tank with double-sided tape and have wires coming out of them.

[wa8yxm]

Common problem.. The factory installed tank flush device is a joke

A Valterra Master Blaster. or better yet a home made version of one, will blast the sensor wall (if done properly) and often clearn the 2/3 sensor.. May or may not clear the 1/3 depending on the install of the toilet.

[Gary RVRoamer]

I like Roebic 57 or Rid-X to clean the walls (and sensors) of a gray or black tank, but it takes time. Fill the tank, add the enzyme treatment, and let it sit 3-4 days before flushing it out. Given some time, the little bio-critters will eat all the scum from the tank walls.

[Wanabee FTer]

I thoroughly sprayed the tank walls with a water blasting wand and solved the problem with both the 1/3 and 2/3 sensors. Didn't make my own because it was only 8 bucks at my local RV store, and it had a tapered nozzle mounted sideways on the bottom of the wand. It seemed to be very powerful. 1 more useful tool I need to keep in the RV. Thanks to all who responded to my post.

[gmanatl]

This is why most manufacturers switched to external sensors for the black and gray tanks. You can add them to a older coach to replace the defective internal sensors. Some say you can fill the tank about half full and add a lot of ice cubes and then drive the coach for a half hour and it will clean them. Worth a shot I guess. I am surprised the gentleman with the 3 year old coach doesn't have the external sensors he might want to check his manual or look at his tanks my 08 Winnie has them.

[RickO]

Quote:

Originally Posted by gmanatl This is why most manufacturers switched to external sensors for the black and gray tanks. You can add them to a older coach to replace the defective internal sensors. Some say you can fill the tank about half full and add a lot of ice cubes and then drive the coach for a half hour and it will clean them. Worth a shot I guess. I am surprised the gentleman with the 3 year old coach doesn't have the external sensors he might want to check his manual or look at his tanks my 08 Winnie has them.

That would be me and yes I do have them. But... they're not working well. The RF theory is interesting. I've had a bucket load of RF stuff going on including the booster for my TPMS and the activation light for my Brake Buddy. At any rate I think a set of See Level gauges is in my future. I want to add the additional panel into my plumbing bay so I can read the levels from there and I think I'll just do it as one major project. Keeps me off the streets and out of the bars.

Rick

[justimagination]

Quote:

Originally Posted by Paul R. Haller Before you drive the thing again use the fabric softener and soap routine but add a bag of ice to the toilet with enough water to slosh around. That will usually do it with a 1/2 hour drive. -Paul R. Haller-

DITTO................DITTO
Good for you Paul, I was just fixing to write basically the same recomendation, but I always try to read threads 1st, give credit where it's due. Ice slosshing around will do miracles. Good luck, happy trails & travel safe.
David G.

[RV Wizard]

The induction sensors are sensitive to being too close to the metal frame of coach. We have had numerous units that read falsely and moving or insulating them from close proximity of the frame corrected the issue.
There are still better systems if you want to spend the money.