kornellred

I replaced the stuck-open thermostat in my 2007 HHR LS a couple of days ago. When I removed the drain plug from the radiator, the fluid that was escaping was initially clear, or nearly so. After a minute or so, the fluid was a pale orange, and it stayed that way until the radiator was completely empty.

The gallon or so of coolant in the drain pan seemed to stay separated into clear on the top and orange on the bottom. There was very little solid residue.

I bought my HHR brand spanking new in August 2007 and have never done anything to the cooling system until changing the thermostat became necessary. I replaced the drained coolant with a 50/50 mix of Dex-Cool and distilled water.

I do not know what 4 year old Dex-Cool should look like, but the separated components were a surprise to me.

843de

Interesting and confusing to say the least. You didn't happen to save a sample of the "stratified" coolant did you? I'd imagine GM might be interested if you did.

I've only heard of DEX-COOL separating in engines that have been severely overheated, then you get an orange sludge-like liquid with a lighter component that floats on top.

Its possible that a thermostat stuck in the closed position could generate some hot spots in the engine causing stratification of the coolant, but one that stuck open as in your case wouldn't cause that.

Did the coolant have a strange odor or anything?

kornellred

No - the drained coolant was not saved (my son disposed of it in the prescribed manner - which we will not go into). As far as I know, my HHR has never overheated (my ex-wife drove it for a few months last year but I think she would have informed me of any negative incident with the vehicle). It runs flawlessly, and with the new thermostat, the engine warms up normally and the temperature remains within a tight range.

There was no strange odor - in fact, the drained coolant did not seem to have much of an odor at all - possibly because it was cold when we drained it.