Black tank reading all over the board

[Peter Dotson]

Hey everyone! Reaching out for some help. I have a 2021 DS 4081. On a trip and black tank is reading all over the place. Started with it overnight registering 100%. I emptied and ran 200 gallons thru the tank flush. Added Liquify tank cleaner to full tank and let it sit 24 hours. Emptied and flushed another 100 gallons thru. It went to 55% on an empty tank. Added another tank cleaner and let it sit unused while we were out for the day. Came back and reading back to 110% and it was not used all day. Ran tank flush another 30 minutes while tapping sensor periodically. Got reading to 45%. Added 5 gallons fresh and we for the day and tank registered 85% on our return. At this point I don’t think it’s a dirty sensor but maybe a sensor failing. Any ideas before I go into replacement? Thanks for your help!

[OMMM4747]

Seems as if you've done as much as you can to resolve the issue by treating, flushing, etc.

Do you regularly treat the tank or did you treat this time due to your current issue? I go the extra step of, at the beginning of every trip, flush the tank, treat and fill to 50-60% so I have some agitation in the tank during the drive. While camping, I add 10 gals of water + treatment after every flush (the tank is never empty). We also add lots of water while using: 1 flush for #1, 2 flushes for #2. I also let the tank get to about 70% before flushing to ensure a good tank evacuation. We were noobs when I came across the attached video.

Hope you can figure it out or someone can offer a workable solution, but for now it appears you'll need a professional cleaning or a new sensor (or both).

Good luck

https://www.youtube.com/watch?v=fs7Y...heJourney.Life

[palehorse89]

When the tank sensors have failed, Newmar installs a pressure sensor. this thread shows a picture of the sensor on the 3" piping. https://www.irv2.com/forums/f103/rec...el-621204.html
In my opinion, the sensor should of been located and installed on the top of the 3" pipe and not on the side........towards the bottom......

[devin66666]

Sounds like a bad TLI "Tank Level Indicator"

[62Morgan]

Those “cleaning” cycles need 24 to 72 hours to do the dissolving job. You did not elaborate; but my first take is you hurriedly did the job.

[erond]

Originally Posted by Peter Dotson

Added Liquify tank cleaner to full tank and let it sit 24 hours. Emptied and flushed another 100 gallons thru. It went to 55% on an empty tank. Added another tank cleaner and let it sit unused while we were out for the day.

I haven't used tank cleaner, just regularly flush every time I dump.

However, I suspect that just adding cleaner doesn't do a lot of good. Keeping in mind that I don't use it.... Add cleaner. Fill the black tank (keep flushing until you are ~2/3 full. If you overfill, STOP! ).

Drive for about an hour or so. Twisty roads. Start stop. Get the black tank to both mix the cleaner as well as slosh it around to clean the sensors. Let it sit. Do one more drive. Drain.

If that doesn't solve your problem, you probably have bad sensors, loose wires, and/or a bad controller/display.

[redbaron73]

Newmar uses an external strip for level sensors on the sidewall of the tanks, these are visible from the wet bay, behind the wall and looking up at the tanks.

Most likely your black tank has the sensor peeling off the tank. Reapply it with a clear packing tape or masking tape. Don’t use conductive tape as it will cause interference.

[redbaron73]

If your coach was upgraded to the pressure sensor, then you have a different issue.

Drain black tank and remove the sensor in the tank side of the gate valve. This sensor can be cleaned and put back in. If that fails then you’ll need to replace the sensor. The parts are no longer available from 3rd party so you will have to order from Newmar.

[rvtips]

Originally Posted by Peter Dotson

Hey everyone! Reaching out for some help. I have a 2021 DS 4081. On a trip and black tank is reading all over the place. Started with it overnight registering 100%. I emptied and ran 200 gallons thru the tank flush. Added Liquify tank cleaner to full tank and let it sit 24 hours. Emptied and flushed another 100 gallons thru. It went to 55% on an empty tank. Added another tank cleaner and let it sit unused while we were out for the day. Came back and reading back to 110% and it was not used all day. Ran tank flush another 30 minutes while tapping sensor periodically. Got reading to 45%. Added 5 gallons fresh and we for the day and tank registered 85% on our return. At this point I don’t think it’s a dirty sensor but maybe a sensor failing. Any ideas before I go into replacement? Thanks for your help!

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Last week or so someone on here talked about a product I think called Restore or something like that.
I can not find it?

[ViperJD]

Erond had a great suggestion. If you don't have access to (or want to pay for a tank cleaning service), fill tank to half way, then drive around. Let the sloshing clean off the walls and sensors. We always prep a trip with 25% tank full of water, and then dump at 75%. Driving in between is really a good cleaning option. In November we paid for tank cleaning service (Kleen Tank, reputable and good team). They said we had no issues, but it was a good check for our technique.

[Peter Dotson]

Thanks everyone for the responses. Red Baron, I was unaware of tank sensor strips in the wet bay-will take a look. In the meantime, I decided to try the “geo-clean” method using a mixture of 20 Mule Team Borax and Dawn in a 2.5 gallon bucket and poured in through the toilet. I then added 20 gallons of fresh water through the tank flush and then drove it for 10 hours to our next stop. Hooked up, drained and tank now shows 0%. Hopefully all that sloshing around is what cleaned it all up. In the future I will be using your suggestions of only emptying at 70% and adding 5-10 gallons of fresh after flushing. The other mistake I was making was flushing with the gate valve closed. I will now always flush with gate open. I also intend to continue to add the geo mixture after each flushing.

Thanks everyone for the input. I’ll be sure to add updates if anything changes.