I was doing a inspection of the car today and found that the level in the coolant reservoir dropped down to about 1.5 inches. The cooling system was serviced very recently (https://www.chevyhhr.net/forums/prob...-refill-57353/) and the reservoir was filled about an inch higher than the full line.

07/31/16 - 72k mi

Engine cooling system drain, flush, and refill
Thermostat replacement

The car now has 75,600 mi. There are no noticeable leaks, but the weather has significantly changed since the time the system was serviced. I came across a post on another forum that mentions that the loss is due to "a combination of evaporation, expansion/contraction due to warm/cold weather."
(How much coolant loss is considered "normal"? - Subaru Outback - Subaru Outback Forums)

Since I did not use premixed coolant, but rather mixed concentrated solution with distilled water, can evaporation be the cause of it.

"Dealership said they pressurized system to check for leaks. On the paperwork was written, "distilled water in premix coolant will evaporate over time since coolant reservoir is not sealed"." (How much coolant loss is considered "normal"? - Subaru Outback - Subaru Outback Forums)

I am pretty sure I burped the system completely...

Anyone else experience similar problems after coolant change.

 

Yeah, I did a change myself using concentrated and distilled and new thermostat.

I filled it up the best I could squeezing hoses and trying to get all the air out.
But for the next couple of days I kept checking the level and topping it off.

And now it's been over a year and the level has not changed it's at the perfect mark every-time I check it.

I would say add a little to make it hit that line or bump and then continue watching it to see if it ever changes.

You can also check oil and exhaust for signs of water, but if it just went down a little and then never moved from there, sounds like you just need to add a little.

 

The purpose of the tank is to account for contraction and expansion of the coolant.
It is supposed to change levels.

If it keeps going down over a short period of time, you may have a problem.

What do you think Prestone uses to dilute their 50/50?
As far as I know water is water and water does evaporate when it is exposed to air. Did you find that to be news?

I image they wrote that on the invoice because they got tired of over thinkers questioning where the water goes.

 

As far as I understand, it is supposed to change levels only while the engine is working and the coolant temperature significantly increases.

"The radiator overflow tank serves as the reservoir for engine coolant that is heated to its boiling point and would otherwise rise up and out of the radiator. Working in conjunction with a thermally activated spring built into the cap, the overflow tank creates a closed cooling system that is much more reliable and practical than previous designs. As the temperature and pressure rise to the coolant's boiling point under pressure, the cap spring activates and allows the heated liquid to flow up and into the overflow tank." (https://www.quora.com/How-does-a-rad...flow-tank-work)

As far as evaporation goes, I never experienced any evaporation of coolant before. I have never added coolant to the system in all the years I owned this car.

So the dealership's answer is a bit contradicting.

 

Top it off, make a small mark on the tank with a sharpie if you feel it necessary, and continue to monitor it.

The coolant heats up and overflows into the recovery tank, and goes back into the engine block as it cools. There can be many tiny air bubbles in the system after a drain and flush, and as they work themselves out into the recovery tank, the level in the recovery tank will decrease.

2 months, 4,000 miles, you don't know yet if it has stabilized until you monitor it frequently. It may have stabilized after a few days, like gio89kid said, but if you haven't been monitoring it, you wouldn't know.

 

All room temperature liquids that I can think of are basically either water or alcohol, they both evaporate Antifreeze is both.

The key to the back and forth is volume. As a liquid heats it expand; as it cools it contracts. It needs someplace to go when it expands. When it cools in a closed system it causes a vacuum.

Different mixes of chemicals in liquid expand and contract at different rates against temperature.

 

I USED to watch my coolant religiously. Just as long as the level is going up when the motor gets hotter and the level drops down when the motor is cool you should be good. Also, Even if you check the coolant level on the engine cold at night it could be lower in the morning; ambient temps DO effect coolant level. As long as its higher than the minimum and not spilling over the top you are golden.

 

I found that over filling the tank actually inhibited the inflow from the engine..

One other thing is that when DexCool overheats it forms a gravelly sediment that will block the hole at the bottom of the bottle. I leaned to remove the bottle and rinse it when doing a coolant change.

 

I just disconnected the hose and flushed it with distilled water. It seems that removing the bottle is not an easy task.

 

After keeping the coolant temp on during a few days of my long commute I realized that my HHR while cruising never goes below 183 and never gets hotter than 219 when sitting in traffic. So I figure if it goes to 181 I may have slight hypercooling going on (Thermostat) and if it reaches 221 I might have low coolant. I think I will peel my OCD brain off the coolant check and just take a gander every couple weeks or every month or so. I was at the point of checking every other day after I had a ghost leak that turned out to be the pressure cap. Replaced about 7 months ago and no change in coolant level since. If you do have a leak start at the top and work your way down! Mine just happened to be the cap so I got lucky.