What did the old thermostat look like? Was it fully closed? It's interesting to put a thermostat in a pan of water on the stove with a cooking thermometer and note the temp at which it begins to open, whether it opens fully, and if so, at what temp.

 

I didnt take the time to do the temp test….it did look ok. I didnt take notice looked like it opened and closed against a rubber seal surface. I wished now I had paid attention to opening dia.
I still have the one took out…I will test it when can.

 

Either way the old thermostat is junk, not reusable or rebuildable.

 

Well, its a fact, Im hard headed and cheap too. I know what all you guys told me about putting AC thermostat in our hhr….but I didnt give the 50.00 for one 3 years ago….I had to but the “substitute” in an fret over engine temp. all that time and then give 65.00 for it…lol. Yall were right, if you dont have AC thermostat….you aint got a thermostat…I was wrong. Car dont heat up nearly as fast pulling up mtns. now and cools back down lot quicker.
So….reminds me of story about substitutes…guy got job working at small town pharmacy….first day on job the pharmacist/owner tells him he has to walk down the block to the bank and make deposit….and if customers come in, he will be right back….and he can sell them anything non-precription on the shelves….if dont have exactly what they are looking for, sell them a substitute. So on the way back from the bank and nearly to his drug store he meets a guy running down sidewalk all bent over holding his stomach. The pharmacist rushes in the store and confronts his new hire….the employee tells him the man wanted cough syrup that they did not have….so he sold him some castor oil instead…said it must have worked cause the man quit coughing….lol
Beware of substitutes.

 

...no one has pointed out to this guy that the normal coolant operating temperature for EcoTecs is between 180-220 degrees farenheit? 🤣

The OP's issue seems like a big fuss over nothing, since 185 degrees is literally within the spec for operating temperature. It's basically nothing to worry about. I suspect he's wasting his money throwing parts at it for a problem that doesn't exist (185 degrees is within spec)

Most of the time in city driving (red lights, frequent stops, etc) mine runs between 190-195 degrees, going up a hill it might creep up into the low 200's before coming back down after cresting the hill (again, 100% normal)

185 isn't "slightly warm", not even close. It's right around where it's supposed to be

 

In post #30 and #34 he posted tge new thermostat improved idle and more. You can be satisfied with 185 F but your HHR might not!

my 2.4 warms pretty quickly to 180, then to 183 and back down to 178 F even though WV it doesn’t go to 185 F

 

Well, concern was how quick it heated up pulling up mtns….and how long took it to cool down. The car never over heated or got above 210….but its winter time now and not to long be really hot in the south.

 

Running a little warm is normal when going up a steep incline/uphill mountain section of highway, I'm pretty sure all cars run a little warm when going up a steep incline (it's just the laws of physics as the load increases)

For example, my previous car (Jeep Grand Cherokee) would run a little warm when ascending some of the steep inclines along I-70 on roadtrips into Utah. The temperature needle would creep up to a bit past the halfway mark on the gauge (but not into the red zone). If 50% of the needle is normal operating temperature, it would creep up to around 70-75% on some of the inclines - then it would come right back down on the descent

My buddy has a Subaru Outback and, you guessed it, it also runs warm and the temperature gauge rises when going up some of the nearby mountain inclines here in Colorado

I'm just worried you're wasting your money, because trying to keep the coolant temp below 200 when driving up steep mountain inclines is unrealistic. The coolant temp rising in said scenario is just something that's going to happen, as long as it doesn't get into the hot zone (above 220°) you should be fine

 

Appreciate your concern….all good now….happy with the correct thermostat