Well this is the first step in my CJ3A preservation project.  Repairing the temperature gauge.  My late brother in law was apparently trying to "fix" my jeep and in what I think was an attempt to remove the engine unscrewed the temperature gauge and twisted off the capillarity tube.  This thread will document my attempt to get it working again.  Plans are fairly simple:  Remove and clean up the brass reservoir, reattach the capillary tube, refill it with ether and reseal it, cross my fingers and hope it is reasonably accurate.  Cosmetically will just repaint the rim around the gauge to keep it from rusting any more.

OK here is what I am starting with.  Fairly decent looking gauge, but the capillary is twisted off at the top of the reservoir, and you can see that it is held solidly in the head fitting by rust.  Going to have to clean out the rust and remove the brass reservoir.

I repaired an original gauge that had broke like that. I made a thread on the 2a page about it. I'll see if I can find it.

Great thread....I too have one that needs repair....

Step by step, problem by problem.  I am pretty certain that I can just insert the capillary tube back into the reservoir and solder it.  However since the flair on the end of the tube is crimped on to the support wire (solidly) not enough of the tube was exposed to do what is needed.  So put it in my vice and gave it a gentle squeeze perpendicularly to the crimp to make it round again.  Worked perfectly and was able to just screw the flair out of the way exposing the tube.  Should be plenty to do the job.  Had it been too short could just cut the wire back a little.  Anyway so far so good  

Yeah me too LOL!  OK, so time to drill it out.  Drilled a hole in a block of wood to hold the brass so I could hold it vertically.  Wanted to set it up so that I could hold it with my fingers so if the bit caught in the soft copper I could let it slip without breaking the bit.  Started with 5/64" and drilled, thought it would go through pretty quickly, figured about 1/4 inch, but was still cutting copper at 3/8 so I stopped, good enough.  Used a piece of 0.024 wire from my welder to make sure the hole was clear all the way through.   Followed the 5/64 with a 3/32 drill to a depth of about 1/8 inch to try to assure a better solder seal.   Needed a little more tubing exposed so cut off about 2 1/2 turns of support wire with the Dremel.   Soldered it.  Doesn't look too bad and flair snugged up to the tube quite nicely.  The next thing was to remove the solder from the other end to see what is there.  Looks like there is a plug in the middle and solder was applied over it after the tube was filled.   Not exactly sure what i am going to do for a fill hole, but might drill and tap for a small brass machine screw, fill with ether and solder, or maybe just JB Weld.  The amount of ether should not be too critical as long as there is enough so that some stays in the liquid state at 212 F.  Should create about 100 PSI at that temp.  So far so good!

I do not know, but there is no way to fill it from the gauge end since the gauge would have been assembled before it was filled.  Since the bezel is crimped on there is no way to get inside of the gauge.  It looks like it was filled then a plug was pressed in.  The pressure from pressing in the plug would have given the concave shape to the end.  Once the plug was in looks like solder was added to seal the plug.  I may drill through the plug and if it is thick enough tap it for a 4-40 machine screw, fill and solder.  Need a higher wattage soldering iron though.

So I found it....

Looks like the bottom was plugged and soldered just as you said....

I'll bet they just hit it with one of those big old industrial soldering irons, you know the ones with about 1/2 pound of iron on the end.  They will do some serious melting.  I think I can locate one.   When I get the hole drilled will check it out with some compressed air.  Looking at the vapor pressure of diethyl ether about 50# should take it halfway (~180).