1997 Monte Carlo z34 over heating problem
 

I have a 1997 Monte Carlo Z34 and the temperature gauge has been acting weird, it goes to hot then quickly falls back down and it will do it and stay at hot for five minutes then drop back down etc. i replaced the thermostat but it still does it. Does anyone have a clue what i could do next? is it the gauge? Thanks for the help.

Did you bleed the system after replacing the thermostat?

yeah....the weird thing though is that it was doing it before i changed it out...i flushed it out as well thinking maybe something might be blocking it a little bit...not sure where to go next though.

I'm just not too familiar with those engines.

ok no problem.

it could be the water temp. sending unit

sorry not sure what that is...i have the haynes manual i will look in there and see what it is.

it'll be under coolant, not water BUT Autozone has it listed as Temperature Switch.
is your car throwing any kind of code? or are you just having gauge trouble?

the only code i have is the purge valve. nothing else.

have you reset the computer since you changed the thermostat and bled the system? on my old S-10 it was done by disconnecting the battery for 30 seconds then hooking it back up. on these cars there might be a different way for doing that.