whats most likely gone bad when my temp gauge occasionally shoots to a higher temperature for a minute, then back down to the real temp? The car is a stock 84 t/a, l69 700r4, thanx

 

When does it do this? When you driving or when you just siting?If it does it when your driving I would probably say the wire going to the sensor probably has a opening in the insalation and is touching a ground when the car vibrates.

 

Or if your antifreeze is really low, you could be getting super hot air bubbles that would do that. Check the coolant level.

 

If it's a fast swing look at the sender located between and above cyls 1&3. It has a single green wire, sometimes it gets burned and will momentarily short to ground causing the guage to peg. If it's a slower change troubleshoot the cooling system.