Blank tank showing full but it is not

[DavidMandiMyers]

2008 American Eagle 42F. When I dump the black tank (40 gal) the sensor reads empty. The tank fills up in 5 days. Two people, normal use. In our 5th wheel with a 40 gal black tank I would dump every 3 weeks. When the tank reads full the toilets will not flush. These are the vacuum dump toilets with the push buttons on the wall. The buttons have sensors that read off the tank also. When the tank sensor says full it deactivates the push buttons. I know we are not accumulating 40 gallons in 5 days. We are home in the evenings and on weekends. We are the only two using the bathrooms. There have been no visitors. Why is the sensor showing full when the tank probably only has 10-15 gallons in it?

 

[AbdRahim]

Perhaps time for deep cleaning. 8 oz of AquaMax in black and gray tanks. Fill the tanks and let them sit for seven days. Dump and rinse. This may need to be repeated several times depending on when they were last cleaned.

 

[Scotttkd2]

Many of us have similar issues, and as much as I would like to be able to let our tanks sit for 7 days, we are full time so not feasible. I add a small bottle of Dawn dish washing liquid every third or fourth fill. Hasnt fixed the issue entirely but it is helping. I have also heard Calgon works wonders, but I havnt been able to find it anywhere but Amazon in foreign packaging. Some have had good results getting the tanks power washed by a tank cleaning service. That is next on my list as we sit for the winter. Wish there was a quick fix out there somewhere.

 

[AbdRahim]

I live in mine most of the time, so what I did was added it on the first use after dumping. The I was conservative with water, in order to get as close to seven daysvas possible. I have tried Dawn, ad other methods. You may have to repeat it several times. Yes I am solo so, I did make it to six to seven days. Otherwise you may have to pay a professional.

I have found that using a chemical regularly helps to keep it clean, after a successful deep clean. I use BluePower after each dump in both gray and black tanks.

 

[Scotttkd2]

Its weird, I have used Happy Camper for years, a dose after each dump and it always worked will in old coach, but Newmar black tank sensor has ben wonky from the beginning. (Fresh tank was also, and I had to have it replaced, but couldnt get dealer to replace the black tank sensor, they always claim operator error). We have bath and half model with macerator style toilets, half bath (mine) on low flush mode, and full bath (wifes) on full flush mode. According to Dometic toilet spec info on a 40 gallon black tank we will fill it in approx 35 flushes. With two 60 yr old plus occupants that is a solid 2-3 days in most cases. I have switched to Unique brand liquid and dont know yet if getting better results or not. Previous owner only had it 3 months and both baths were in full flush mode, so I dont think I inherited and tank issues, just sensor issues.

 

[surgdoc4]

Dumping takes a couple of minutes to get black water out, then flush tank and it takes a long time to get the all the TP out. Using clear angle it is easy to see. If you don’t flush the tank every time you are making a paper machete cast of your tank. Then it is a huge problem

 

[Scotttkd2]

Yup, been flushing blank tank after dump for 15 years, if RV didnt have a flush I aded one. Newmar has a long standing issue with their electronics and tank sensors.

 

[surgdoc4]

After 25 years of RV ownership I have had to fix every system. Electric is the worst with water/septic a close second. The less expensive ones arrive unusable until fixed and the expensive diesel pushers systems fall apart long before the heart stops. The sensors get coated and nothing short of manual cleaning seems to help. They are all junk and the only way to avoid having fixing every system is to get a new one when the problems start. I haven’t had a Newmar but I know the tank sensors in Monocos are hard to get to. Try filling the tank with hot water and an industrial floor cleaner let sit until cool, flush and repeat. Be sure to ask the wife if she accidentally flushed a makeup bottle ( that happened ). I found it with a scope before the confession. A scope can be very revealing. Good luck, all part of the fun of RV ownership.

 

[DavidMandiMyers]

Thanks to all of you for the input. Several mentioned Newmar - Is American Coach Newmar? - If so I wasn't aware of that.

Since my sensors are showing "E" after I dump I decided to do some measuring. I filled the black tank with water until the gauge showed 3/4. Then I drained it into a 36 gal portable tank. Much to my surprise it almost filled it up. I guess these vacuum type toilets, I don't know the actual term for them but the brand is Tecna, use more water than I realized. I really don't see the need for the full flush. So we are using the economy flush about 95% of the time.

Looks like I will be dumping the black tank every 5-7 days. I put Happy Camper in after every tank drain. I also fill and occasionally back fill with water until I have clear water going out.

 

[Scotttkd2]

Good ide to check the specs on the electronic or powered toilets, they will tell you the gallons per flush. It is a lot higher then probably gets used in a regular dump flush model. (No macerator). Glad you got it sorted out!