2010 hhr 150k miles, changed water pump, thermostat (oriellys 180 degrees), upper radiator hose, and spark plugs. Old plugs looked good no sign of water. filled radiator (using green antifreeze), will go up to 217 fan kicks on and will drop to 195 or less. I can drive it all over town not a have problem, but eventually get in traffic temp will go up as high as 230, can get out of traffic rolling down the road, fan running and temp will not go down unless turning on heater can get it to 220 or so. Not losing any water not seeing any leaks. Any thoughts or ideas?

 

1st thing. Wrong antifreeze. Your car is supposed to have Dexcool. That green stuff is not considered compatible in the HHR and other folks have reported temperature issues when using the wrong stuff.

You also could have an air pocket in the cooling system. If you didn't "burp" the system when refilling, that is a strong possibility.

Change to the correct coolant and then check back here.

 

Agree, sounds like an air pocket. I had very similar experience after flushing the coolant, until I got it burped properly. Here is our mod oldblue's burping method
And keep monitoring the recovery tank, I would say every morning for 2 weeks. George is right, the green stuff is not the best product for your engine. It only lasts a year or 2, while DexCool lasts up to 5 years, and is formulated for this type of engine.

 

Agree, assuming this started happening after the change. Probably have no heat.

 

Welcome to the site!

What RJ posted. Saves me typing and making spelling errors!, thanks RJ

 

ok, i have been watching the coolant level and burped the system. I cannot find any external leaks, but the car is using coolant, i keep adding water. Spark plugs look good, oil looks good. It takes around 16-20 min before temp starts rising past the 185-195 area. I can drive it 5min, and idle in the drive way for ten min, then it will start rising. Possibly partially plugged radiator? Considering i am losing coolant, i am thinking about renting a radiator pressure tool? Any other ideas?

 

If you are losing coolant, that's probably why it's overheating. Some possibilities: radiator cap, trans cooler lines(inside and outside the radiator), and on or near the thermostat housing sometimes develops a pinhole. The waterpump weephole(top) and drainplug(bottom).

There's no evidence of coolant in the oil, or oil in the coolant? Maybe there was some old sealant that didn't get cleaned off the waterpump sealing surfaces when that job was done. Or the transfer tube may be leaking.

But if you can't find any external leaks, then it's likely internal. Is there no white smoke out the tailpipe? You say the plugs are good, how good? Clean like steam cleaned?

Bottom line, it's either leaking externally(as liquid or steam), or leaking internally(into the engine oil, trans fluid, or combustion chamber). It sounds like the leak is significant, you ought to be able to find it.

Here is a thread on how to flush trans fluid level. Post #1, starting at step #13, is how to check the level. If you pull the plug and a lot of greenish-reddish liquid pours out, you will need a new radiator, trans fluid flush and filter, and flush the coolant(and replace with DexCool). Here is the link
https://www.chevyhhr.net/forums/how-...-change-58325/

 

OR, There was a huge air bubble that is slowly venting. OR, a clogged heater core.

Are you checking the coolant under the pressure cap or in the bottle?

 

I would try the least expensive method, replace the "O'Rileys" stat with the GM stat. It would not be the first time this has happened.

 

Ok, replaced radiator and lower hose, filled with DEXCOOL, took the thermostat out, but i don't notice the coolant flowing. I replaced the water pump, has anyone ever had a pump with bad flow or just doesn't work well? with the thermostat out, coolant never looks like it is flowing and it slowly overflows out the filler neck.