2010 Chevy Aveo LT over-heating, rumbling start up issue

[Mumachan]

So not an hour ago I was stopped at a red light when I noticed my thermometer going from normal 1/2H to 3/4H.

I turn on the heater to make it stop heating up as much but the air instead of being hot is actually cold O.O which is something my Aveo has never done before. If I put it full blast hot I get all toasty inside.

When I stop moving it heats up quicker and there are short intervals of hot air and long cold ones. The thermometer doing the same thing, from 1/2H to 3/4H.

***Recent Observations***

When starting the car cold it does a rumble like either the spark didnt catch right, or liquids arent pumping all around well enough. I had to turn the car off and on again for it to 'catch' and be fine. I changed the sparkplugs and the problem died for a good 3 weeks then began again.

I haven't checked my radiator to see if maybe I ran out of anti freeze (what I think is the issue) but this month alone ive filled the tank around 4 times. Is this normal?

**Work done in the 3 past month**
Replaced Thermostat (at dealership)
Oil change
New Battery
New Sparkplugs

[gothstone]

Unless you have a more obvious hose or radiator leak, sounds like time for a water pump and gasket. Since you will already have it that far apart, do the timing belt, timing tensioner, and idler too. And check your serpentine belt and serpentine tensioner as well. You should pretty much never need to add antifreeze, its a closed system. Oh, and before you do this, look at your oil. If it looks like frothy chocolate milk you have a blown head gasket, and its gonna suck. But its probably just the water pump, and you can do it in day. There is a pretty good write up in the how to section.

[Mumachan]

Unless you have a more obvious hose or radiator leak, sounds like time for a water pump and gasket...

So my bro drove my car without permission and the water pump blew up. Good call bro, good call...

[2010AveoLT]

Unless you have a more obvious hose or radiator leak, sounds like time for a water pump and gasket. Since you will already have it that far apart, do the timing belt, timing tensioner, and idler too. And check your serpentine belt and serpentine tensioner as well. You should pretty much never need to add antifreeze, its a closed system. Oh, and before you do this, look at your oil. If it looks like frothy chocolate milk you have a blown head gasket, and its gonna suck. But its probably just the water pump, and you can do it in day. There is a pretty good write up in the how to section.

actually, the Ecotec Engine Water Pump is Driven off of the Drive Belts, but if the Mileage is more than 100K, then I see no reason not to Change the Timing Belt and Pullies. (i'm actually about 40K away from having to do a Timing Belt Change myself)

[gothstone]

oh, I missed the 2010 part. My bad! I don't know much about 2nd gens.