Don, I did test all 3 thermostats on the stove with a thermostat and all of them opened at 180 albeit one slower than the other. Once I loaded the thermostat onto the car the overheating continued. Not until I recently removed the thermostat all together did the car stop overheating or causing the boiling in the reservoir.

Without the thermostat now the car runs absolutely perfect if not for the cel and dic not reading out a temperature. I have been closely monitoring it with my phone and the attached elm reader and around town tops out at about 156 and with heavy driving at 181.

I should receive the brand new thermostat tomorrow but I feel like once I install that I'll be back to boiling again.

 

You just ordered the ACDelco thermostat in the 23rd, is it there already?

 

Through Amazon. As a prime member it takes 2 days. I'll have it by tomorrow.

 

I guess you have noticed that your A/C doesn't work anymore.

 

Yes, as I mentioned if not for it affecting the ac here in Arizona I might consider leaving it as is. We are averaging in high 90's right now.

 

Update?

 

Funny you should ask. I installed the new AC Delco thermometer and started doing test drives.

I just returned from a third test drive.

Again peculiar - The car starts to over heat at times causing the reservoir boiling during the first test drive. The last 2 drives the temperature climbs to 230 to 240 then drops to 210 212 for no apparent reason. I just got back where it did this and no boiling???

So far the drives have been relatively short. Tomorrow I will take it for a more extensive drive to see if it maintains the lower temperature once it drops from the higher temps.

 

When it’s cold, check coolant level at the cap on the hose between the rad and engine.
Let’s just call it the rad cap, when you come back , try and park the HHR with the front bumper up hill, so any air bubbles can burp out, and I know it’s hot out but , rolled the windows down and turn off the A/C and crank up the heater, full blast for say, ummm, 10 - 15 miles of your trip. Also to help burp any air out of the system

 

Yes, I have burped it and check before every trip to make sure coolant levels are topped up, but get the same result each time.

 

What is this resevoir you mention where the coolant boils - are you talking about the expansion tank?