Repair a temp gauge lead?

[SDLars]

I'm curious, has anyone ever been able to repair a temp gauge lead? Seems like most gauges are OK but the sensor end is always messed up.
 

[Christopher Mikesell]

The temperature bulb is filled with a liquid which vaporizes and expands when the temperature increases. A capillary tube connects the bulb to the gauge, which is a pressure gauge. When the tube breaks or the bulb gets a hole or crack, then the liquid evaporates and it does not work. There are shops which can rebuild them, but it is more expensive then buying an expensive american-made (Rochester) replacement. Someone I know at the local airport had a temperature gauge rebuilt since it had an exceptionally long capillary tube (rear cockpit) that wasn't available new. If they bought a new one, then they would have had to have it rebuilt anyway to get the corrrect length tube.
 

[Joe (Wa)]

Christopher is totally correct. I've done several gauges and mostly thermal expansion valves (TXV). The link is basically how it is done.

The problem is mostly a broken or otherwise leaking capillary tube. Cut out the bad section out and splice or splice in a new section. Before final splice fill the bulb near full with ether. You may have to calibrate the gauge to make it more accurate if desired. Back in the day we used R-11 refrigerant which has a compatible temperature - pressure curve with nearly all gauges. Splices were silver soldered.

Joe
Temp gauge repair