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Moeller Gage

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dick seiders

Well Known Member
Installed a new Moller Gage last year in my new welded tank and following about an hour of 7 t.o. and landings noticed that while the Dynon was showing decreasing fuel my Moller was not. I finished with 4 gal in the tank (and B. Betty screaming ) and 15 indicted on the Moller dial. I banged my fist around the gage and the tank feeling it was stuck and maybe I could dislodge the arm to get a correct read to no avail. I removed the dial and replaced it with a spare I have and it's not the dial. I presume the arm is stuck in the almost full up position.
Has anyone experienced this besides me and if so how did you fix (short of removing gage hopefully)? All ideas are welcome. Thanks.
dick seiders 120093
 
I made a decision to not do ANY of the fuel tank mods (frangible bolts, vent lines or Moeller gage). I use a nylon instrument tube to sound my tank when I don't fill it to the cap and I calibrated it during my fuel gage calibration. If anybody is interested I'll post the dimensions for 5, 10 and 20 Gal marks.
 
OK. I wrote them down today at the hangar. I'll get them tomorrow. They will look a little strange, but it's because the sounding tube hits the tank bottom "upslope" of the lowest point on the tank bottom, so the 5 Gal Mark is only about 1.5" from the end and the 10 and 20 Gal Mark look more linear. I have found the tube levels to be within a gallon of my Dynon indication.
 
dick seiders said:
Installed a new Moller Gage last year in my new welded tank and following about an hour of 7 t.o. and landings noticed that while the Dynon was showing decreasing fuel my Moller was not. I finished with 4 gal in the tank (and B. Betty screaming ) and 15 indicted on the Moller dial. I banged my fist around the gage and the tank feeling it was stuck and maybe I could dislodge the arm to get a correct read to no avail. I removed the dial and replaced it with a spare I have and it's not the dial. I presume the arm is stuck in the almost full up position.
Has anyone experienced this besides me and if so how did you fix (short of removing gage hopefully)? All ideas are welcome. Thanks.
dick seiders 120093
Click to expand...
Don't know what your welded tank looks like, but, heard of an instance (just bad luck) where a drop of tank sealant from a screw on the front flange landed and hardened on the Moeller gauge gearing. Next time the tank is empty and out, turn it upside down and listen for the thump of the Moeller float.
 
The dimensions on my sounding tube are:

1/4" OD Nylon instrument tube with overall length of 32"
5 Gal Mark - 1 1/2" from the end
10 Gal Mark - 6 3/8" from the end
20 Gal Mark - 14 3/8" from the end

The nylon tubing is stiff enough to let you feel when it hits the tank bottom and gives consistent readings. You should score the tubing marks with a three corner file on the OD because magic marker will dissolve in the gas. Just stick the sounding tube down the filler neck until you feel it hit bottom, put your thumb over the end and pull it out to see the tank level.

I don't use it much because I usually top off before each flight and I can see the level in the filler neck, but it's good to have on cross countries when you didn't see the guy fill you up and you can't see the level in the neck. Gages are great, but I always like a visual verification of fuel level during preflight.
 
Interesting comments, thanks. I may make a measuring stick as described. Marty, I don't remove my tank anymore at annual inspections as the welded tank doesn't require any mods and additionally I have sectioned the baggage panel as others have suggested.
I will perhaps have to remove tank if the thing can't be unstuck, but am aiming for other methods of un sticking it first. My present plan is to find a magnet strong enough to try to rotate the vertical geared shaft with the dial removed of course. If successful I will share the results, or maybe if unsuccessful as well. Has anyone tried this yet?
dick seiders 120093
 
I used a cheap 6ft $15,- flexible video camera endoscope from eBay to inspect the inside of my tank.
Maybe you can try that to inspect the Moeller gauge (tank was empty and well ventilated).
 
Gagarin737 said:
I used a cheap 6ft $15,- flexible video camera endoscope from eBay to inspect the inside of my tank.
Maybe you can try that to inspect the Moeller gauge (tank was empty and well ventilated).
Click to expand...

I wouldn't recommend sticking anything lighted/electrical into a vapor laden fuel tank.

Regards,
 
Borescope with tv screen offered by a friend, but I am skitterish about putting it in the tank. I'll work the magnet idea first, but thanks for the suggestion.
dick seiders 120093
 
Isn't the Moeller Gage mounted with 5 screws like other fuel level senders? It should not be hard to remove it. Of course then it requires mixing up some proseal to seal it. I do not trust those rubber gaskets that come with fuel senders.
 
dick seiders said:
Borescope with tv screen offered by a friend, but I am skitterish about putting it in the tank. I'll work the magnet idea first, but thanks for the suggestion.
dick seiders 120093
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Dick,

If you have the fuel tank vent option installed, perhaps you can remove the top tank fitting and run a wire into the tank to release the float arm. Be sure to ground the wire to the tank before inserting it.

Regards,
 
You can always pick up a bottle of nitrogen or argon at a weld supply house hook it up to a hose down the filler neck to inert the tank if you are worried about sparks or ignition sources from a lighted bore scope.
 
Interesting stuff. My aim is to keep it simple. I am reluctant to place anything in the tank that could produce a spark for obvious reasons.
Neutralizing air in tank is not simple for a simple guy like me. Removing the bad gage is an option if I can't break the float loose with a strong magnet. The nylon measuring rod sounds like a good alternative option as I am not inclined to stick in another of the same gage that failed in only one year of use. Pulling my tank is no different than pulling the original and if I put in a new gage and it fails in a year that's two pulls of the tank which is not going to be necessary if I
a) break float loose
b) ignore it and just remove the dial as it is inoperative
c) use the measuring tube as a spot check
d) do whatever other good thing someone may suggest
Thanks for the help all.
dick seiders120093
 
I must be missing something. Why do you feel you have to pull the tank to repair or swap out the Moeller gauge? Sorry, I don't remember exactly how it is mounted.
 
If you mounted the gauge per the plans removing the screws will be an issue. If I remember correctly it does not have nut plates in has nuts on the inside. Although the pro seal might keep them from spinning I would not bet on it.
 
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Dick does not have Van's tank. He has a welded tank. It seems that for some reason, it is difficult to remove the Moeller gauge to inspect it.
 
I saw the Vans plans for the Moeller showing nuts on the inside and thought "this is really dumb." Sorry! Really don't understand that decision. Also the lack of a gasket and the use of proseal.

Nutplates and a gasket.
 
I just spent 20 min writing a response and the system deleted all but the last sentence just as I tried to load it.
Basically what I said was removing tank is no big deal. What I dislike intensely is having to remove not only the gage but the dynon sending unit access plate so I can be sure no trash proseal is left after fix.
I attached my gage with a doubler with nutplates as opposed to the plans screws and nuts.I stuck the doubler to inside Of tank top skin in the hope it would stay there if I remove the screws. I am planning on continuing the magnet effort to see if the float breaks loose. Beyond that I am not certain as I am not inclined to install a new gage as I know some only last one year. I'd be more inclined to opt for Schallers measuring tube.
I am still open to any other ideas and I appreciate the helpful thoughts. It would be nice if we can come up with a game plan to help any others who have a gage problem on down the road.
dick seiders 120093
 
My experience has been that sometimes it is easier and quicker to go ahead and do it the hard way to start with, rather than trying to figure out an easier way. :)
 
I know all about that ,Joe. The problem is not in the doing it's determining what it is I want to do. Either way I go I am certain I will not install another Moeller gage.
Thanks for the thoughts.
dick seiders 120093
 
Bill_H said:
I saw the Vans plans for the Moeller showing nuts on the inside and thought "this is really dumb." Sorry! Really don't understand that decision. Also the lack of a gasket and the use of proseal.

Nutplates and a gasket.
Click to expand...

Actually, using the gasket is really dumb if you use any fuel with ethanol in it.

As for the lack of nut plates, I can not comment.... I was not involved in the engineering of that installation....
 
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RFSchaller said:
Scott, with regard to your comment on the gasket wouldn't it depend on the gasket material?
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Yes.

I made the assumption that the included gasket would be the one people would use.

A cork gasket would not be influenced by ethanol but it has a some what limited life span (it will leak, the question is when) so I wouldn't recommend it either.
 
According to the Moeller website: http://www.moellermarine.com/sites/moellermarine/files/mm148_dyk_ethanol.pdf

"3. Ethanol’s ability to cause swelling of common gaskets and O-rings materials, such as XX% of Buna-N and XX% of Nitrile, increases fuel flow restrictions causing poor engine performance. Moeller’s forward thinking fuel system components have been designed and engineered to withstand many of the harsh deteriorating effects of ethanol blended fuels."

The also say that sealant is not necessary but if used should be one that is compatible with ethanol. So it sounds to me that they are vaguely familiar with ethanol in gasoline...
 
Ok I have gotten over my frustration of learning that even tho my welded tank is about perfect there may be a reason I have to pull it out. Actually I owe it to myself and to all of the 12 flyers who are using the gage to find out what the problem is and with that revelation I pulled it today. Now the interesting part is the gage was stuck in the 7/8th position. The why is unknown but the float was binding on it's shaft to the extent that one could move it easily, but it stays in whatever position it is placed There is sufficient drag and will not move unless I move it. I nstalled about one year ago and functioned normally until 10 days ago. I have the old gage from the former tank and it moves freely with no drag. The stuck version has no junk in the works at all. It is clean. The one difference is the little shaft that the mechanism rotates on has no end to end play. It is tight.That is why it's not rotating. Question is whydid it get tight? Is it possible the plastic housing swells? Have no idea. but what happened to mine could happen to all or none. I will try to reach moeller tech to see if they have any ideas. With all of these that may bein use it would be nice to know why this one failed.
Thoughts or ideas?
dick seiders 120093
 
That's really cutting to a fine degree as the gage fuel volume displaced isn't a factor after you are down to a half tank, but ok it's a good thought.
Update on the Moeller mystery is I have called several times and Moeller's voice message says they will call me back......
Newest interesting info is I brought the stuck gauge into the house last nite and this monring it is free of any drag with the float arm functioning normally. Maybe something is swelling up??? If so that's is a problem. We'll see.
dick seiders 120093
 
Update on the Moeller gauge for fuel:
The gauge is actually produced by Rochester Gauge Co. of Dallas Texas. It is a model 6781 and is designed to be used for diesel fuel. I spoke with their tech. assistance and when I described the events I have covered in this thread they advised me of the diesel issue. Now I don't know if the premium motor gas with ethanol makes any difference and tech did not know that either, but suggested the fuel may be causing the plastic housing to swell. . Also I cannot return it for evaluation as only the original purchaser may do that so hopefully Scott has been following this thread and will advise us next step, if any. I may call Vans anyway for guidance. They also suggested I can conduct my own test which I will do for further enlightenment. I plan to submerge the operating portion of the gauge in the fuel I use for a few days to see what happens. I will post the results. In the meantime I am going to install my old gauge from the original tank (yeah, yeah, I know what I said earlier) in the new tank and get the airplane flying again. I will post results of my test as it develops.
dick seiders 120093
 
dick seiders said:
Update on the Moeller gauge for fuel:
The gauge is actually produced by Rochester Gauge Co. of Dallas Texas. It is a model 6781 and is designed to be used for diesel fuel. I spoke with their tech. assistance and when I described the events I have covered in this thread they advised me of the diesel issue. Now I don't know if the premium motor gas with ethanol makes any difference and tech did not know that either, but suggested the fuel may be causing the plastic housing to swell. . Also I cannot return it for evaluation as only the original purchaser may do that so hopefully Scott has been following this thread and will advise us next step, if any. I may call Vans anyway for guidance. They also suggested I can conduct my own test which I will do for further enlightenment. I plan to submerge the operating portion of the gauge in the fuel I use for a few days to see what happens. I will post the results. In the meantime I am going to install my old gauge from the original tank (yeah, yeah, I know what I said earlier) in the new tank and get the airplane flying again. I will post results of my test as it develops.
dick seiders 120093
Click to expand...

Being in the process of installing the Mechanical gauge I am curious to find out where you stand on the issue mentioned above.
Thanks
 
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