What would cause a temp gauge to suddenly stop working?

[Stewart G Griffin]

i put the probe in boiling water and nothing.  Also, when removed from the intake it was definitely touching water.   i think time for a new gauge.  These were the cheap Chinese ones from summit:
http://www.summitracing.com/parts/sum-g2924/overview/

My theory is they worked fine all along until last month i ran the motor to about 260 degrees---was caught in a traffic jam and i still have not put a fan on;  See my other post entitled "waterpump pulley to fan bolts"
http://forum.73-87chevytrucks.com/smforum/index.php?topic=12865.0

My theory is the gauge couldn't handle the high temperatures.   Well, it worked great while it lasted.  i got it and the oil pressure gauge for $14 back in summer 2006 at Summit.

Has anyone used the Autogage Ultra-nites?

[Stewart G Griffin]

This dual gauge set, oil press+water temp, is now $19.95 at summit.  So, you figure $9.50 per gauge.  What do you expect?   You get what you pay for.

Forget about Ultra-nites---i just found out there's no way to hook up lighting to it.

i'm going to go with the cyberdyne unit that has been sitting on my shelf for a while.