When starting car, Temp gauge rockets up all the way and does not read anything. Gauge gets power. I have swapped the gauge with a new one and it worked for a little while, but eventually shot up like the last gauge.

Any ideas on what could be causing this? Thanks!

 

sounds like the sending unit in the drivers side head is bad, if im not mistaken the gauge will peg to the top if its not getting a signal

 

Are you sure you've got a gauge sender and not an idiot light sender? Obviously the light sender only has two settings (not overheating & too late) as where the gauge sender is variable. The spike when you turn the key to start is normal.

 

idiot light sender? Yeah im aware that the spike when key is turned is normal, but it stays spiked. Ill go with what Wwwyzzerdd has said, thanks for your help!

 

Yeah, idiot light sender. As in there were two gauge cluster options, gauges and idiot lights. If the head, engine, or sending unit has been changed before it's possible (and not at all unlikely) that the sending unit might be an on/off switch for a warning light instead of a varistor.

If you want to isolate the gauge from the sending unit, without spending money on a new sending unit, and going through the trouble of changing it, just unplug the green wire from the sender. Unplugged the gauge will default to the resting position. If you ground the green wire it'll peg the gauge. If the gauge responds correctly, it's a safe bet it's the sender. If it stays pegged it's in the gauge or the wire is grounded someplace.

 

Had the same problem after swapping out gauge clusters. Both my Temp and oil pressure gauge turned on then pinned to the top. Changed the sender and got life to the temp gauge. Unfortunatly the damn thing always reads too hot and is not calibrated correctly. So basically my gauge is useless, ha. Everyone freaks out when they see it and thinks I'm overheating when I'm not.