Temperature fluctuation after overheating

[whitedragond]

Here's the situation. I have a 1996 Camaro RS. About 2 weeks ago, I noticed that my temperature almost hit redline when driving home.
Did the basics, new radiator cap, flushed coolant, new thermostat (185 lower temp one).

It doesn't overheat, but what I did notice.. when idling, then temperature will continue to rise.. when it hits about 210 or 220ish (just above half) the two radiator fans will turn on and cool the engine down to the quarter mark. They will then turn off and it will heat back up again and continually do this. Before it would stay around the quarter mark and not fluctuate.

Any ideas why this would happen?


some side notes... My air conditioner hasn't worked for a few months (probably needs recharging, as it's cool for a few mins, then goes warm) and my Cat Converter has the same temperature on the pipes going in as going out. I know there should be a 100 F difference, but there isn't and I don't know if this would affect the engine doing what it does... I also heard that if you start the car, turn on the MAX a/c to full, the fans should immediately kick on.. they do NOT do this, only when the engine temp goes high enough.


Thanks for your help

[CDNFB]

Re: Temperature fluctuation after overheating

Temperature fluctuations like you describe are in most cases caused by vapor locks forming and then clearing, and can be from a variety of sources like low coolant levels or head gasket failure.

Check for air in the cooling system. If you have the bleeder screw (3800 II) open it when the engine is hot and see if any steam or air comes out. If you find steam or air, then you found out how it's overheating. Then you would have to look at why the air is in there.

Your fans are working normally when they come on above half (indicated).

As for the when A/C is on, my A/C works and the fans come on right away when I select the system on.

[96camarolover]

Re: Temperature fluctuation after overheating

These cars also have a special process u must go thru when u put coolant in the car, Best way is to have the car running of course add coolant rev up let the level go back down and add more, and also do what CDNFB said, Check for air in the system if it continues...Also when the car is just sitting and idling it will rise to 210-220 and then fans come on and goes back down specially when u start driving again.