I have a 2006 HHR with 2.4 engine, my temperature gauge moves up to the third line and stops. The dash coolant sign goes from 187 to 217 and then the fan cuts on until it goes back to about 205. I have only water in it right now because I did not want to waste coolant if there was a problem. The over flow tank bubbles and discharges water after idling for about 15 minutes. While driving the temperature goes from 192 to 217. I replaced the temp sending unit but got the same results. Any suggestions

 

Also I did put a new water pump on.

 

At those temps it's not really running hot. Pay no attention to the analog gauge and which "line" it's at. Those gauges are NOT accurate.

What ? No coolant, only water ? I guess you realize that straight water has a much lower boiling point than the correct coolant mix. Also, water has no lube or anticorrosion characteristics.So did you drain the coolant and replace with just water ? And what do you mean by waste coolant ?

 

Sounds to me like you have the wrong t-stat. It should be 180F. Use ONLY a ACDelco 131-158!

The fan should not come on until the temp gets to about 217F and turn off when the temp gets back to 180F.

Don't even bother looking at the analog gauge. Plain water will boil at a lower temp than DexCool.

You might want to check the fan relay or just replace it, it is cheap.

 

X2 on the thermostat, other brands don’t operate within the computers expected parameters.
You will have to go back to 50/50 Dexcool, not the green stuff!
You will need to burp the cooling system

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

 

Firemangeorge, I put in another engine because it threw a rod, I just wanted to get it running to make sure everything was ok so I put in water only, once it run ok then I will put in a antifreeze..

 

If you are sitting in the driveway (No air flow) then those characteristics are absolutely correct. The fan turns on at 217° and cools it down. If the A/C is turned on then the radiator fan should run all the time. If you are driving down the hiway at 60 mph and it climbs to 217°, I would say something is not right. I dont think it would get over 200° running 60 mph on flat hiway on a 90° day. I understand you using water instead of dexcool for testing purposes. As everyone says water boils at 212°, but we are talking about a CLOSED system, when the water is under a mere 15lbs pressure this changes the boiling point closer to 250°. I think you're ok using straight water for testing, just dont forget to drain it and put dex-cool in when you are done. So I need more details about rpm's, ambient temp, mph, incline of street and your temp before we can make a final conclussion. also check the numbers on the thermostat to make sure it is the correct AC Delco thermostat, like everyone says , it does make a difference.

 

That's very true about water in a Closed cooling system but............
The OP stated "The over flow tank bubbles and discharges water ", so that would not be in a part of the closed system. Part of my reasoning for saying straight water is a bad idea.
Sorry, but trying to save $10 by not "risking" putting in Antifreeze ............not me.

 

The overflow tank bubbles ? I missed that, check the pressure cap. After you burp the system.

 

The plain water boiling into the overflow.