This is the procedure I followed from 2CarPros, I've added my own comments in red. Note that the instructions were for a 2007 Aveo with manual transmisison and no a/c. My car is a 2005 with a/c and AT. Sorry no pictures - I'll try to add later.
- Drain the coolant (It has a drain plug. Standing in front of the car looking into the engine bay--look to your left and straight down below the top radiator hose. Look along side the radiator; near the bottom on the side is a black plastic plug that is hex shaped (approx. 12 mm) with a cross slot in the head of the hex.
If you put a light near the top radiator hose shining down, you can see the plug when looking thru the lower horizontal slot in the front fascia.)
- remove 2 nuts and 1 bolts to loosen up the powersteering resevoir. This thing is totally in the wrong place for this job and complicates the whole thing. There is a recommendation farther down to remove the battery and battery tray. I just removed the battery and had plenty of room.
- there is a hose that goes from the resevoir down to a pipe. This pipe is affixed to the front of the car with a pclip and nut. Remove the nut so you can move the resevoir a little better. I didn't bother doing this.
- remove the fan shroud (2 bolts at the top of the radiator, disconnect the electrical connector to the fan, then pull out, The bottom passenger side is held in by a clip. I had to pull pretty hard to get it un stuck. On my fan shroud, there is just two bolts holding it. One on the top and one on the drivers side. There is no clip on the passenger side. I can't recall, but there may be clips on the bottom. The fan electrical clip must first be removed from the shroud (pull towards the drivers side) and then it can be simply pulled apart. I had to carefully us a set of pliers to get mine apart.
- disconnect 3 hoses (upper, lower, and a small degas hose?) The upper hose is hard to take off of the radiator neck due to limited space. You can take off the thermostat housing, but this is another gasket and potential leak when you are done. I opted to loosen the passenger headlight housing which gave me enough room to remove the upper rad hose.
- remove the transaxle oil cooler lines and one retaining bolt. The upper line (source) is bolted on, the lower (return) is held in place by a hose clamp. Account for one bolt and washer for the upper line. Some oil will leak out of the hoses and cooler when removed.
- remove the two mounting bolts at the top of the radiator. Note that the rad is NOT bolted to the AC Condensor (thing that looks like another rad infront of the actual radiator. The rad is bolted to the rail that runs between both headlights and simple rests in place. Once the two upper bolts/brackets are removed, the rad is now free. You DO NOT need to remove anything associated with the A/C system. I've seen posts where people discussed disconnecting A/C lines. Perhaps this is a requirement of earlier models, but I doubt it.
- at this point I was able to wiggle it out of there by lifting the passenger side up and dropping the drivers side down until it had rotated about 90 degrees. Again, the powersteering fluid resevoir was RIGHT in the way and made taking it out a big pain in the butt. You might take out the battery and see if that gives you more room to push the resevior back.
I did remove the battery and it gave me the needed room
- the vertical passenger side of the fan shroud had rubbed through the radiator. I used the dremel cut enough of the fan shroud away so that it will not rub through on the new radiator. I am going to take it to a radiator shop today and see if they can just fix it so I dont have to buy a new one.
- install the new rad, reversing the removal procedure above. Be careful not to damage the fins or tubes of the new rad while installing. As an added precaution, I put a piece of cardboard in front of the rad once it was place - you will remove the cardboard when you are ready to install the fan shroud.
- one precaution for cars with AT is to ensure that the upper cooler oil line is started by hand to avoid stripping. Torque this bolt to spec once finger tight. Not doing so will void the warranty. Something that was not mentioned is whether the washer for the upper oil line is a "use once" compression washer and therefore would need to be replaced. I would recommend using a new one regardless. I initially had a small leak on this line with the old washer.
- continue hooking up components in reverse of removal. Follow appropriate coolant refill and system purge procedure. I added a 50/50 mix of Dexcool and distilled water until I reached the minimum fill mark. I then ran the car until the coolant got up to temperature to check for leaks. I left the resevoir cap off initially to "burb" the system of any air. Then I screwed the cap down and ran the car for a few miles and again checked for leaks.
- you may need to add abit of ATF to the transaxle to replace the amount the was in the cooler and in the lines (AT only). Not sure how much this would be, but best to check AT oil level following owner manual and using this to determine how much to add. GM recommends no more than a pint if AT oil level is low.