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Old 11-30-2016, 02:05 AM   #1
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Holding Tank Sensors

You guys post the best advice, I should have come here first. But I didn't?

We bought your 2013 36FB last November. The black, grey and galley holding tank sensors have always shown 3/4 to 100% full. I first tried the Geo Method for several months because of past success with my previous RV. Then I tried treatments off the shelf; and finally ordered Tank Tech RX and the enzymes didn't do the trick either.

I have now dropped the insulation blanket to expose two of the holding tanks. With the nuts removed, the sensors will spin and move in the rubber grommets but not come out.

I took pictures of my sensors to the closest RV dealer and the Parts Manager said the Stainless steel pins were not replaceable but were permanent to the tanks. I asked about drilling holes beside the sensors and installing replacement sensors. He said the fix would be temporary and prone to leaking. Probably sludge has accumulated and new sensors would fail soon.

I suspect the original owner of my RW stored it w/o having emptied the tanks. For whatever reason the water lever doesn't report correctly but that's only an inconvenience. I'm not looking to create a real problem.

Does anyone have a suggestion?


Howard & Patti

2013 Redwood 36 FB adopted Nov 2015
2015 GMC 2500 Denali Crew Cab
Cocka-Poos - P.T. (Phineas Taylor) & Baylee
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Old 11-30-2016, 02:48 AM   #2
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holding tank

Had 95 Georgie Boy that done same thing...with stainless steel pins as u say u have I put 1/2 gallon of muratic acid the kind u buy at lowes for concrete cleaning for about 36 hours...of course tank must be FULL of water also...then flushed it really good..cleared my problem
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Old 11-30-2016, 04:42 AM   #3
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when i had my Scepter had the same problem.. Here is a suggestion..for the black water tank..Hook up the unit. Put about 1/2 a tank of water then 5-6 bags of ice and go for a drive for about an hour. If there is deposits on the walls it should knock it off and clean it up. For the Gray water tanks I have seen people use the type of spray head used for Black tanks. Feed it into the tank from outside and turn it on. Put a 5 gal. bucket under the discharge pipe to collect the gray water. If you want to inspect the inside of the tank you can rent from Home Depot a "SEE SNAKE" that you can feed into all 3 tanks. it has a light and camera on the end so you can see if really there is deposits.
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Old 11-30-2016, 10:44 AM   #4
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Usually the probes on the fresh tank are spin welded in. The grey and
Black are usually installed by drilling a hole. If you have the mutant loose they should pull out. They are designed to be a tight fit. They sometimes use gutter seal type caulk to prevent leaking. Look online for valterra or Horst probes. If your old ones don't clean up you can replace them.

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Old 11-30-2016, 03:15 PM   #5
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The best solution & easiest is don't mess with them, don't change them, quit trying to clean them, & just ignore them, none of the rvs we've had/have were worth the the time it took to install them.
We also have the FB & fulltime so from experience the black will last 7 days, the galley tank (which is the kitchen sink & dishwasher if equipped) will last a week unless used heavily, & the other grey I leave open as it will last about 2 days( its the lavatory, shower & washing machine if equipped). The toilet will make a noticeable different sound when flushing when it's time to dump.
Danny & Linda
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Old 11-30-2016, 04:03 PM   #6
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There are sensors made by sea level that adhere to the outside of the tank which solves the clogged sensor problem. They connect to the factory wiring and then you replace the tank gauges. They work excellent but are a little pricy
2015 36RL pushing a 2015 Denali
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Old 12-02-2016, 01:05 PM   #7
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Sometimes, it's an electical problem. I had similar issues from day one and found that factory had wired my fresh water tank sensors in the wrong order. The other tanks were correct. That fixed the issue.
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Old 12-04-2016, 03:26 AM   #8
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I went down and bought several boxes of denture cleaner pills, filled the tank with water and dropped all the pills down inside the tank thru the toilet. Let it set and clean for a day then dumped, the sensors worked better. This was on one of my older RV's, I did the same with the grey water tank too, but was a bit harder to get them into the tank, I had to drop them down a vent pipe under the sink and flushed on down into the thank by running water in the sink. Hope this helps.
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