That’s what I thought, head gasket. I changed the temperature sensor and the t-stat today and no change. There was big difference between the old stat and the new one, the orifice was 1/2” bigger in diameter. I had my hopes up for a second but no luck. Looks like I’m replacing a head gasket, entire engine, or junking the car. Bummer!

thanks for all of the support!
James

I’m going to check later in the week, if it makes it. I’m really thinking of getting a Chevy Volt. Kind of makes me sad.... Im at the point of too much money and time being spent on this car.

Well, I went a drove the volt. It’s not for me! New engine from eBay. I’ll mess with the old one once it’s out and on the ground. Kind of a shame, I wanted to run the miles up on that thing..... 217k and still going just get warm on long grades. I can see a bubble in the coolant filler cap every 10 seconds and it failed the hydrocarbons test. I did switch the thermostat and it runs much better, I wonder if there is a separate part for the non turbo hhr. I have 3 stats and one is much bigger in the opening. Makes me think I bought the car with the wrong one, replaced it with the wrong one before getting the correct part installed? Who knows? The new engine goes in 10 days. Any suggestions on other parts to replace with it. I already have a new turbo, wish I wouldn’t have bought that, I would have rather just bought the complete motor for $3400. With fuel injectors, turbo, hoses and everything.

I had my mechanic replace the engine. The car runs great as always, I’m still having issues with cooling. All new GM coolant hoses too. New long block from ZZP. Now the car will get hot when the heater is on, but it’s not predictable. It seems like when first driving, (15 miles) if the heater is turned on the temp will keep climbing (216) until I turn off the temp selector back to cool. Then the temp drops quickly down to 199° with normal driving. If coasting it will be at 194, Im still confused why there is such a drastic difference with the temp in this car. I have heard about air being trapped in the cooling system, I’ve done my best to get it out, not sure what else to do. I have check the T-stat on the stove it opens the temp each time.

Seems like there’s air locked in the heater core, try burping the cooling system.

I can hear the variable speed fan working. Not sure if it’s working correctly. Again today when I first start driving turn on the heater and the temp gets to 216 and I turn off. After driving 25 miles heater turned on and temp stays at 200. The temp stays at 199 with AC on. I’ll leave the heater on and see how high it gets. Just super confusing for me.