Tank Level Sensors - Printable Version

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+--- Thread: Tank Level Sensors (/showthread.php?tid=2421)

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Tank Level Sensors - RussWhite - 07-21-2015

Just want to share my recent experience with tank level sensors.   My vintage uses penetrations through the plastic tank walls at the 1/4, 1/2, 3/4, and full points.  There is also a common penetration at the 1/4 level.  That makes for a total of 5 sensors per tank, and 10 sensors per coach.

The common sensor for my potable tank started leaking on my most recent trip. I was also experiencing poor operation of the sensors on both tanks.  That was new as the potable tank usually gave a good and reliable reading.

The common sensor for potable is in a difficult location directly behind the Mach5 water pump with very little room to even see in there.  It took my flexible camera and display to even find where the leak was coming from.  As I felt around with my hand back there, oh no, the sensor just fell out and a stream of water flooded the bay.   I opened the tank drain and let the rest directly to the ground until it reached the 1/4 level and stopped.  Since I was at the factory at the time I inquired about replacement sensors.  My service advisor thought they were in stock and my visit to parts did not go well.  With Creslie in tow the next time, we determined that Newell no longer stocks these sensors.  I taped over my hole and went home.

I decided to try removing the high level sensor figuring if I screwed it up it would not matter much since it was at the top of the tank.
Eventually I removed 9 of them.  Some can be pulled out with vise grips, other don't want to come out at all.  For those I ran a nylon web strap through the jaws of the vise grips, wrapped the web around my waist, looked around to be sure no one was watching in case I fell on my butt, and pulled for all I was worth.  That got them out!

In this post I will show pictures of the corroded sensor as well as the others.  They are all in some state of deterioration including being pretty well covered in mineral deposits.  

The thickness of the tank wall and the diameter of the hole do not fall in the range of sizes that grommets are available for.  Or at least that is what I decided after much searching.  In the end I made my own sensors that seem to be working very well. Now tank levels in both tanks work perfectly.  A few tips if you plan to make yours too.  I used #6 hardware as #8 ( what was there ) was just a bit too big since I had to put a nut on the inside of the tank.  My rubber plug just matches exactly the hole diameter.  I had to drill a hole down its center to accept the 2" #6 SS screw.  That is a bit tricky as the rubber wants to expand and the hole you get is smaller than you expected.  But soon I learned what size bit to use and was turning out my ten new sensors.

I used LocTite on the nut and when dry pushed in the sensor, centering the plug and have about 1/8" beyond flush and each side.  A few turns of the outside nut and it expands the plug and it is leak tight.

I removed the water pump and water filters to make access easier, but was never able to get access to the high level sensor in the waste tank.

Some picture attached.   Russ

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RE: Tank Level Sensors - Richard - 07-21-2015

Not meaning to be dense, but is it really a sensor? Looks like a screw, or I missed something. If that is true then the panel is just looking for conductivity between the bottom common screw and the others?



GREAT POST!

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RE: Tank Level Sensors - RussWhite - 07-21-2015

Richard,

The level is detected just looking for the difference in resistance between air and water. The "sensor" is just a penetration into the tank so the circuit board displaying level can sense the resistance and display the proper level. What I hope folks understand is that over time that stainless screw may become coated or corroded and could be a source the source of any problem they are having with level indication. Russ

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RE: Tank Level Sensors - LynnJeff - 07-21-2015

Early on we also had instrument issues regarding levels

Ultimately went to Garnet Technologies in Granbury Tx

They have a system you use on the outside of your tanks that will work with existing lead wires from old existing systems

Easy to put in and has been absolutely accurate

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RE: Tank Level Sensors - bat73 - 10-09-2016

my tank monitor on the lower panel does not work, anyone know where I can have it repaired, there was a shop in Houston that did it but there no longer in business

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RE: Tank Level Sensors - folivier - 10-09-2016

Make sure the plug has not come loose from the back of the panel. Other than that, sorry can't help.

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RE: Tank Level Sensors - bat73 - 10-11-2016

(10-09-2016, 10:35 AM)folivier Wrote:  Make sure the plug has not come loose from the back of the panel.  Other than that, sorry can't help.

tks for the reply, I have had it out and all connections are secure, Newell tells me they used this system from 89 to 03, maybe I can find one from a coach that's being parted out

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RE: Tank Level Sensors - ccjohnson - 10-11-2016

Possibly Dinosaur Electronics?? Chime in here Gurus who have used them. I might be interested in the inside temperature display on panel above microwave if they have those also.

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RE: Tank Level Sensors - Fulltiming - 10-11-2016

The units that Newell used were made by PMMI Electronics. They were located in Houston about 5 years ago but are likely out of business now. Their old website was www.pmmi-electronics.com which is no longer active.

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RE: Tank Level Sensors - bikestuff - 12-15-2017

Russ,

I think i may be up next for this fix. My fresh water tank reads as empty even though it’s full. That makes me think my common (Bottom) node is out. i was able to follow your post but was wondering about the rubber plugs. What are those?

The solution of sealing with rubber compression was truly inspired!

Bill

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