temp gage problem

The indicator needle on the temp gage in my '91 caprice has gone full hot, actually out of sight and stays there. What would the fix be? A set of under-dash gages? Could it be the sender? Thanks.

Most likely the sensor. Cheap and easy to replace. Not exactly sure where it is on the TBI. BTW, it is almost NEVER the gauges themselves. That is one thing GM got right.

A co-worker told me today that he has disassembled some GM clusters to access the temp gage and moved the indicator needle to free it and the gage worked again. Next question is...how do I get in to the needle?

I would not move the needle. Change the sender first. The needles are not happy when removed, and reinstalled.

On a TBI it is between the #1 and #3 cylinders behind the exhaust manifold. You need a sensor socket to keep from breaking the end. Since it enters the water jacket, you need a sealer on the threads. If you get the old one almost out, and are ready to insert the new one, you can make a quick swap with a minimal loss of coolant. Do not attempt it with a hot engine.