mine was making that water rushing sound, took it in, the tech filled it, but he filled it, ran it, filled it, ran it, and filled it must be hard to get it full he showed me a aluminum tube on the back side of motor that he suspected as the culprit it carries water from one end of engine to the other has 0 rings at each end said he saw a little crud at one end. He wants to look at it again in a couple months see if there is more he cleaned it when he was there. You might look there yours might be worse.

 

If you have no sign of a leak, best possible scenaro would be the bubble discribed in an earlier post. Worst possible scenaro, bad head gasket or cracked head or block, and coolent in getting into the crankcase, or into the cylinders. That would be bad, but you should be covered by the warrantee, which you probably will be very grateful to have.

 

Thank you There's a couple of ideas. The o-ringed tube sounds the best so far. Small enough to let coolant evaporate while being driven. Burping, maybe. But over three years? Evaporation? If it stayed the same for three years, why the sudden drop in 3-4 months? All good leads, though.
Unfortunately, the car is out of warranty. These dealers are tough. When it says 36 months, they mean 36 months.
I do recall a relatives Suburban that had dexcool. And constant leaks. The dealer kept putting some kind of walnut or almond shell tablets in it until it stopped leaking. It was actually in the manual, with a part number. After the warranty expired, he flushed pinkish mucous looking stuff out, put prestone in, and it stopped leaking. I hope I'm not headed there.

 

Keep in mine that with the colder weather some things expand at diiffrent rates. not uncomon to have a little seeping here are there are normal as long as there small. just keep an eye on it I guess that every thing will be fine. good luck

 

Doesn't the 2007 have a five year 100,000 drive train warrantee? If your problem is head gasket, head, or block related it should be covered by that drive train warrantee.

 

Our 07 HHR had that one time coolant loss that you seem to have had. The thin upper hose on the tank had a kink and I had to stick a smaller stiff hose inside of it to reinforce it.
40K miles later we have not lost a drop.

 

my 08 tank hose had a kink too, only I put a stiffer & larger hose over the oem one to hold the kink out smoothly..
This way I did not reduce flow to the tank & back..

Never a leak tho, just didn't like seeing the kink...

 

I suggest doing a block test to eliminate the possibility of a bad head gasket, cracked block, etc. Here is an excellent video (test car is not an HHR):

http://www.youtube.com/watch?v=QA7KVQq9vKA

Thermostats with a vent hole will help resolve air bubbles, and, in unfortunate cases, exhaust gas bubbles.

 

Did you mean a pressure test for cooling system ?

 

No, a chemical test for exhaust gas in the coolant.