I was driving in my 86 Z28 and I looked down to see what the temp was at, well it was behind zero. I'm not sure if the spring in the gauge went bad or if anything else could cause the temp gauge to go offline. The fans work properly and overheating was never an issue. Any suggestions?
Thanks

 

Check the wire connector to the Temp sensor located in middle of the head on driver's side.

 

Everything there looks to be in good shape, I can't tell if it went less than zero, or all the way around past top temp. (I can't see the end of the needle because it's resting behind where the faceplate for the guages are)

 

Make sure the needle isnt stuck on the bezel. With the key on to electrics, disconnect the wire to the sender and ground it to the frame. If your gauge spikes, then your gauge/wiring is fine. If not, something is wrong with your wiring/gauge. It's most likely your sender going bad. I had the same problem as you, and just replaced my sender and my gauge works great now. BTW, I got it at NAPA and heres the link to it:

http://www.napaonline.com/Catalog/Ca...641_0166850493

There are ALOT of different "senders" and "switches" that auto parts store clerks will say are the right part for our cars, but most are wrong. I originally got a sender that didn't work for my camaro, even though the clerk said it would. The one in the link works.