Today I have tackled the task to change the coolant (5 years old) and the thermostat (still good, but I thought it might be due anyway some time in the future with 130'000 km and 11 years) on my manual 2008 2LT. I had ordered the ACDELCO 131158 part. The new part (left) is a bit different than the factory installed one (right). The old one has a kind of arc bracket on the upper side whereas the new one has a flat bracket. Also they look a bit different on the underside. I installed it anyway.

Now to the issue where I am stuck now: I have completely drained the coolant according to the detailed instructions I found on this forum and in the Haynes manual (radiator plug and water pump plug and recovery reservoir). Now I would like to refill it with clean water to flush the cooling system once or twice. However I could only fill in about 2.5 litres until the radiator opening overflowed (total coolant capacity is 8.4 litres). I ran the engine for a couple of minutes with heating set to Full. Warm to hot air started to come out of the vents and the water temperature reached about 70°C. Then I checked whether I could add additional water, but I could not as the water still allmost reached the top of the radiator opening.

Is this expected behaviour? Am I doing anything wrong? Could it have something to do with the thermostat being a bit different than the old one? How am I supposed to fill in 8.4 litres if I am already stuck at 2.5 litres? I didn't run the engine for more than a couple of minutes out of fear to run the water pump dry. All this stuff is completely new to me, so I much appreciate any help :-)

 

Best to flush and fill without the t-stat. if you lose any coolant it is only an oz or so.

 

If you only ran it for a couple minutes the thermostat was probably not open yet to let coolant circulate into the engine.

 

Thanks for your replies. So it is normal that only 2.5 out of 8.4 litres fit in at first?
And I can either remove the thermostat for filling or else wait until the temp reaches 88°C and the thermostat opens, which should make room for more filling?
Would it help if the reservoir cap is left open during this process?

 

No you’ll waste Dexcool spilling out as it heats up

 

Here's a summary of the latest state:
- I drained the coolant from the radiator and the water pump. Unfortunately I did not measure how much came out. In my view more than 6 litres / 1.6 gallons came out. But I am not 100% sure.
- I replaced the thermostat (131-158).
- I refilled it with a Dex-Cool mix, but I could not get in more than about 4.8 litres / 1.2 gallons.
- I tried different various tricks and tipps regarding burping, but to no avail.
- Water temperatures look fine (albeit maybe 2 to 4° Celsius cooler than before). It is around 82° Celsius / 180° Fahrenheit during driving under low load. Went up to 97° Celsius / 206° Fahrenheit in traffic jam. Came down again to thermostat temperature afterwards. Fan kicks in at about 104° Celsius / 219° Fahrenheit when revving up on location. Temperature comes back immediately after stopping revving.
- Coolant is at the reservoir bulge level when cool. Goes up maybe two inches when hot. Goes back to the bulge level when cooled down.
- Heater starts blowing warm to hot air long before thermostat temperature is reached. So this looks ok, too.
- Coolant is always at the same level when checking by opening the pressure cap.

So....
-> I am under the impression that I got more coolant out than I got in. Big air pocket somewhere?? But coolant and cooling behaviour look ok.
-> Assuming that I overestimated the amount of coolant that came out: is it possible that even after draining radiator and water pump, about 3 litres / 0.8 gallons remained somewhere, maybe in the heater core?? (8.2 litres / 2.15 gallons total coolant capacity minus the 4.8 litres / 1.2 gallons I got in)

 

The capacity is actually 8.2L as per your owners manual. But 8.2 vrs 8.4 - that's a minimal difference.

If you refilled it with a Dex-Cool MIX, and did not add the prescribed amount of straight Dex-Cool, then you most likely do not have a sufficient amount of Dex-Cool. For a 8.2L capacity cooling system you need 4.1L of straight Dex-Cool, assuming the remainder in the system after flushing is plain water.

If you didn't measure the amount of fluid drained - don't worry about it (you will never be able to drain the full 8.2L as some will always reside in the cooling system).

The main concern is that sufficient amount of straight Dex-Cool is added ONCE the system is flushed well with water, and drained again. Ie: drain/flush with water/drain again/add 4.1L of Dex-Cool.

RJ gave a great detailed description on the whole process for the 2.0L motor, but most of it applies to the other engines as well - https://www.chevyhhr.net/forums/how-...lant-ss-57387/

 

2.4L engine w/automatic is 8.0L/8.5 Qt.
2.4L w/5-speed 8.2L/8.7 Qt.

The .5 qt goes in the recovery tank. I was never successful getting the full compliment in. I recommend flushing and filling with the t-stat out; installing it later does not lose enough to worry about.
If you are being OCD you can get a specific gravity tester for a dollar or 2.

 

One last suggestion. As you get closer to the 8+ liters, you will definitely get more in with the front of the car higher than the rear. I did mine on ramps. If you have it level, you can still have air pockets. I filled mine, drove it hard enough to generate heat, and the refilled just once. Use the gravity!

That's what worked for me. I don't think the SS is that much different than the NA cars for engine cooling.

 

Burp! While you are driving it to warm it up crank up the heat to full, it’s a good thing!

https://www.chevyhhr.net/forums/how-...-system-60614/