Monday, August 11, 2014

The Fuel Gauge

I spotted several Jungmann fuel gauges for sale this week so I decided to check mine just to make sure it was repairable. With the help of Brian Karli I managed to get it apart without any damage. It looks like with a new spring and some seals it should be OK.
Here is what it looks like all together, these five are for sale at
The top of the gauge unscrews from the threaded boss that screws into the tank.More on the little piece in the middle later.
To disassemble the gauge sight glass you have to remove the safety wire on the top nut. The wire is brass and the pigtail is normally pushed down into the slot.
I used a drag link socket that I have ground down to fit the main jet of a Stromberg Carburetor . The right tool is important here to prevent damage, I used just a little heat from a propane torch to loosen things up.
Here it is disassembled just two seals at the top and bottom and the glass tube.
It is important to notice that the lower nut is peened together and will not come apart without considerable effort. You can see the peen mark in this picture.
At first I could not get the lower half of the gauge apart, the seal had become hard and I had to break it to remove the float assembly. Here is a shot of the seal in place.
I soaked this with corrosion X for a couple days and still could not get it apart, I finally managed to dig into it and break the seal so I could get it out. Here are a couple pictures of the top and bottom, looks like it was rubber at one time.
With the seal removed I could then remove the brass guide tube and the gauge rod/float assembly.
Unfortunately the guide tube came out in three pieces where the solder joints had failed. Should be an easy fix. Here are the three parts, the lower flange, the tube, and the upper spring retainer.
I am pretty sure they go together like this.
I am not sure what the spring does but this one looks trashed.

Is the ferule at the top of the guide tube supposed to hold the top of the spring ? Looks like I need a new spring anyway.  Here is the seal that was under the guide tube flange.

Overall it does not look too bad, a new spring , seals, and some solder should fix it right up. Suggestions/advice are always welcome at

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