Ok... In the owners manual it says you need 7.4 quarts of coolant.

Well, I'm assuming that's a mix of coolant/water to total that? Or do I need 7.4 quarts of coolant, and another 7.4 quarts of water?

 

7.4 quarts is the total capacity for the coolant/water mix.

 

Ok, thanks! That's what I figured, but then I started questioning myself, LOL

I don't know why...but it seems like it would hold more than that in it... But, I guess it is a small engine. 2 gallons doesn't seem like much.

 

When we do a coolant flush on a 4 cylinder it takes 1 gallon coolant and the rest water. These engines are famous for air pockets so make sure you pat it on the back so it burps.

 

Ok, will do, thanks!

Yeah, I figure since it's now 6 years old might as well flush the coolant this weekend. I've never done a flush before... Usually on the Lumina I'll drain and refill what comes out. Anything special I need to know about flushing it? I figure just let it drain out, then spray a hose in until water comes out?

 

Drain, Fill, run, shut-off, drain, fill, run, shut-off, drain.... until it drains clean. Someone posted something about a second drain in addition to the rad to help drain as much as possible.

(rad petclock is on the passenger side at bottom of the rear of the rad - hard to see from up top, but you can feel for it - the petclock can be fragile so don't go using no pipe wrench on it :)

It's important though to not let the water pump run dry, as the engine runs, as that can toast the water pump seals in sort order.

Once it drains clean, add 3.7 quarts, or 1 gallon as per ChevyMgr to just make it easier, and top it up with water.

 

And don't freak out if you don't get exactly 7.4 qts back in. Sometimes when you drain a system, well, a little bit can remain inside.
As ChevyMgr said. Make sure to burp that baby to get all the air out.

 

Thanks for the tips guys! Like I said, flushing the coolant is new to me, and since I plan on keeping this car a long time I want to keep up on stuff to keep it running for years!

 

If you have a sudden spike in engine temperature when you're done, or you can't get all the air burped out, take it to your dealer or a good radiator shop(ASAP). They'll be able to put your HHR on a device that pulls a vacuum on the cooling system to evacuate the remaining air.

Its really important to work deliberately and carefully to get all the air out, a pocket trapped in the head can cause rapid and very damaging overheating, then you are looking at a cracked head/blown gasket.

 

The block drain is on the water pump. Make sure that your pressure cap is the correct one, says "radiator" on most, "surge tank" on 2006 and others that have a surge tank. They look to be the same, but the "surge tank" ones do not allow fluid to return from the overflow tank, thus causing the "air bubble".

My first method was to mix up 2 gallons of 50/50, pour 1 gallon into the "radiator", then measured by the quart, left over goes into the overflow tank. It is unclear whether the 7.4 gallons includes the tank.

My other method was to drain, refill until draining was clear water (using only the radiator drain), then pour 3.5 quarts of DexCool into the "radiator", top off with water while engine running cap off toss the other 2 cups into the overflow ant top off with water.

Oh, and siphon the old fluid out of the overflow tank, or pull it out and dump it. Don't forget the heater on high (that's an old timey thing probably not necessary). There is a heater bypass hose, so that fluid always flows around the t-stat to some degree.