I have a 2008 HHR LT 2.4 l, it overheats when accelerating or climbing a hill. I've replaced the radiator, cap, water pump, thermostat, and all hoses, I've also replaced the catalytic converter! No oil in coolant, no coolant in oil! Thought maybe the sending unit was faulty, but if it gets to about 230 degrees, it starts acting like it's vapor locking! It seems to cool down some when at idle! Any suggestions?

 

The fan should come on at about 217F or when the AC compressor is running.

 

Welcome to the site, perhaps a good burp is in order!

https://www.chevyhhr.net/forums/how-...-system-60614/


Now, I don’t know, so I’ll ask, what coolant did you use? What thermostat? What water pump? Did you replace the balance shaft chain or use the hood tool?

 

Dexcool, 180 degree, ac Delco, and used the tool.

 

And the water pump, plastic impeller or metal?
Is it possible the balance shaft chain isn’t engaged?

 

Is the AC condenser full of bugs or otherwise clogged?

 

Are you trying to outrun a Hellcat SRT or climbing these hills at 80 MPH?

 

I’ll second that. If the water pump wasn’t running it wouldn’t cool down much at idle.