CLEAN SENSORS!

[John From Detroit]

Well, as all of us who have waste storage tanks know, Getting those stupid sensors clean so they properly show when the tank is empty is right next to impossible.  I've heard lots of suggestions, Ice cubes,  Dawn (regular, not anti-bacterial) and so forth.

Right now, as of today, the sensors on my black tank (and the grays for that matter but that has nothing to do with this) properly show EMPTY (And empty it is)

Here is what I did.

You know those want things you stick down the toilet... Well, they don't work, too weak a jet

So I took some 1/2 inch PVC, a hose end fitting (Female would be best but not having that I used a male end and an adapter I already had "in stock") a 90 degree "Street" elbow and an end cap,  Drilled about a 1/8 inch hole in the end cap... This gave me a very nice high pressure stream, single stream, and by aiming it (I used the printed line on the pipe as an aiming guide) I managed to blast all the crud off the sensors, and very likely that entire end of the tank and a good part of the rest of it as well. Now I don't have a camera and light source to lower into the tank (Actually I do have a camera small enough but it's mounted in the side of the motor home) but if I did I'd bet those sensors would sparkle.

Sure is nice seeing the proper reading on the display though

 

[Smoky]

I thought the sensors were on the outside of the tank.  I am pretty sure they are on the Newmar.  Adjusting them is a matter of tweaking a calibration wafer.  Still good to keep the tanks clean though.

 

[Tom]

I thought the sensors were on the outside of the tank.

Smoky,

Many are not, such as the ones on our Monaco. I've been considering adding the ones on the outside as a replacement, but didn't get around to it yet. Glad to hear that Newmar uses the external ones.

 

[DougJ]

John, this is just about what I had done at the northwest regional rally of WIT, Cashmere, WA, in May, by Flush-It Northwest.

They don't need to be near a sani dump or sewer connection because their truck has a holding tank.

They first empty the tanks.  Then they put an adapter on your tank exit that has threaded through it (and hence into the tanks) a small diameter pressure hose delivering a high pressure spray courtesy of a little pump that they use.  They also thread through a camera and cable so that we can see what's happening even as we view what's dribbling out of the tanks.

In my case, mega gunk!!!

Now my sensors work and I'm trying to keep them that way by doing at least two, and often times three back flushes, even when the sensors show the tanks as empty after the first back flush.

Ciao,

Doug

 

[Jeff]

I had our tanks pressure cleaned after the FMCA Pomona rally last spring. Took two hours to get the sensors clean enough to read empty and a week later the black tank started showing full again and the grey is getting erratic now. Unless you have your own equipment like John I am not sure the fix is a long term one.

I have been periodically using the Dawn treatment without results.

 

[Jackliz]

I thought the sensors were on the outside of the tank.  I am pretty sure they are on the Newmar.  Adjusting them is a matter of tweaking a calibration wafer.

Hmmm. Do those outside-the-tank sensors work well?

Thanks,
Liz

 

[Smoky]

Liz:

They work perfectly for us.? Have not even had to go through the calibration procedure yet, after one year of use.

We do have the input for a second hose to do a complete tank flush.? We use it religiously.? In fact, when we hook up, we hook up with two hoses, one for fresh water and the other for the built-in black water tank flush.? After we empty the tank, we shut the black water valve and let the flush run for one minute.? Then open the valve for another dump.? We repeat this three times to assure a good cleaning.

New on the Newmar front.? Apparently they are going to let go the Fleetwood guy they hired as president of the company and who got rid of the three year warranty.? The son of the owner is supposed to take over the reins again.? He said he wants to re-establish many of the old policies.? We are having a wonderful stay here at Camp Newmar and got all kinds of nice work done this weekend.? We are under the old three year policy (last Kountry Star off the 2005 assembly line and last one to get the 3 year warranty).? Some talk of going back to the 3 year warranty but more likely a 1 or 2 year warranty with perhaps a discounted extension warranty. Rumors abound.? But definitely a return to some of the more customer oriented policies.

We are enjoying our new windshield and lots of free updates after a week at Camp Newmar with full hookups.  We will be heading westward at a leisurely place.  This is the first time we have no deadlines to meet and we can stop at will and wander.  We had several MHs we were going to meet in Black Hills, but one by one those plans fell through.  So now we are considering other routes to take.

 

[John From Detroit]

I thought the sensors were on the outside of the tank.  I am pretty sure they are on the Newmar.  Adjusting them is a matter of tweaking a calibration wafer.  Still good to keep the tanks clean though.

There are a couple of different types of sensors, One or two types go outside the tank and are more or less unaffected by minor build up inside the tank,  The regular sensors, used by most low end MH's are nothing more than bolts and the "stuff" in the tank completes an electric circuit, This is the kind I have, and if they get crud built up on them they can fail, either showing empty if the crud does not conduct (which almost never happens) or full if it does (common)  Mine now work properly

 

[Smoky]

Glad you got em working John.  Not nice guessing at blank tank status! 

 

[DougJ]

Took two hours to get the sensors clean enough to read empty and a week later the black tank started showing full again and the grey is getting erratic now.

Jeff, it's been longer than a week for us since we had our tanks pressure flushed and the sensors still show empty when the tanks are empty.  I'm thinking that you just can't  dump and leave it at that; you've got to dump and back flush at least once.  We're doing two black flushes, and sometimes a third one just for good measure.

Ciao,

Doug

 

[Jeff]

So do I'

 

[Clay L]

Hmmm. Do those outside-the-tank sensors work well?

Thanks,
Liz

I think they work better but they are not always the answer.
Winnebago went standard with a outside tank sensor system in 2005 on their Class As - that would be about 20 minutes after I bought mine - of course.

I added their system but the crud is built up on my tank walls so much that the black and grey still read full when empty.
I did the same thing John did with a pressure washer and got the black tank working okay but it crudded up after a while and quit working. I do not have a flush in my  black tank (or my grey for that matter) and there is no easy way to add one that will hit the tank wall where the sensors are placed, so at this point I am living with the problem

I suspect that full timers have more problems with this than more casual RVers. I talked to several guys with the new system and theirs all worked great and later realized they did not use their rigs like we do ours.

A full timing friend installed another brand - one that shows percentages - and his doesn't work properly either.

 

[Pat]

I quit relying on working holding tank sensors years ago.  Fortunately, though, my red indicators still seem to work.  I just estimate. 

How do the external sensors work?  I would think they still have something run through the tank to the inside. 

--pat

 

[Sorcisto]

I can understand sticking the PVC elbow thing in the black tank(thru the throne) but I don't understand how you clean the grey water tank?

Mine could use it now.

Sorcisto

 

[Jeff]

You can purchase kits to retrofit a sprayer to your holding tanks. It requires accessing the exterior of your tanks to drill a hole and install the spray head but can be done.

Filling your tanks with a combination of water and a bottle of Dawn dish detergent or other grease cutter and then driving a few hundred miles does a  pretty good job of softening up the crud so it can be sprayed off if it isn't too far out of control.

 

[Clay L]

How do the external sensors work?? I would think they still have something run through the tank to the inside.?
--pat

The ones I am familiar with are capacitance based. A capacitor is two pieces of metal separated by something - air, plastic, glass, etc. The material separating the metal pieces is one factor that determines the value of the capacitor.
By sticking two strips of metal foil to the outside of the tank and connecting them to a capacitance measuring circuit, the tank contents can be measured because the capacitance value changes as the fluid in the tank rises.

 

[Clay L]

You can purchase kits to retrofit a sprayer to your holding tanks. It requires accessing the exterior of your tanks to drill a hole and install the spray head but can be done.

Filling your tanks with a combination of water and a bottle of Dawn dish detergent or other grease cutter and then driving a few hundred miles does a? pretty good job of softening up the crud so it can be sprayed off if it isn't too far out of control.

The problem I have with a sprayer is that I only have access to the wall the sensors are on and I have not found a sprayer that sprays backward with any force.

Over the years I have tried all the things I have seen posted to clean the walls including dawn, tide, pine sol, ice cubes, calgon water softener, and so on.
So far nothing has done the job. Once I even put in a half gallon of drain cleaner with the tank 1/3 full of clean water and drove it for 300 miles. That did zip also.

So mine must be out of control!

 

[John From Detroit]

I can understand sticking the PVC elbow thing in the black tank(thru the throne) but I don't understand how you clean the grey water tank?

Mine could use it now.

Sorcisto

Well, at this time I don't have a problem with the gray tanks.. .Just the black tank had a problem

The method I use won't work with the gray tanks... Unless you do a whole bunch of work  I'm hoping to avoid problems with the gray as opposed to fix them

 

[Pat]

I read to use a bottle of Realemon juice in the tank and drive. I tried it once, and it cleaned off one sensor, which promptly went on after the tank filled past that sensor, and it never went out again. 

--pat

 

[Master-Tech]

Hello All,
Hey guy's try something cheap n easy,,,
When u pull up camp 2 leave dump your tank's shut everything back closed , Go inside hit tha pantry and take your
ordinary 89 cent Morten Salt step in tha Bathroom ,, KICK the Pump on an slowly dump the salt down the Toilet,
Adding enough water too dissolve tha salt then add about 5/7 Gallons water , Then head out ---- Let the salt-water
slosh around till You stop again //// May take a couple times but it'll clean those corroded sensors, probes,,
If no luck check into the main ground on tha tank ,, may need 2 move it,, away from the other 's
? ? Good Luck
? ? Master Tech