I was installing a new stereo system and checking all the fluids and timming and afterwards I forgot to tighten the radiator cap all the way and a bunch boiled out. I filled it back up and tightened it all the way and now my temp is all the way to the right past the red. I had to get it home so I drove easy and had the heater cranked but there was not any hot air comming out. When I got home(3 minute drive) The engine seemed to be as warm as usual. I checked the radiator again and all the fluids and thought everything was fine. My wife was driving it to work and about 5 minutes from the house she called me and said that it was past the red on the temp guage again.
Any help would be appreciated.

89 GTA 5.7 Fans work, mostly stock, Fluids are fine.

Brian

 

Also, I put a new aluminium radiator in it about 3 months ago.

Brian

 

I have had this problem on a few cars I have owned. It sounds like a stuck thermostat. I swapped out the thermostat and the problem went away each time.

 

Is that easy to do on a thirdgen. I helped a buddy do that on a 98 Z28.

Brian

 

Weird thing that I just noticed. When I run it in town the temp is around 230 when I get on the highway it jumps up past the red. And it will sometimes go down when I am breaking. Does it sound like my guage is broke?

Brian