i dont exactly know wats wrong with it but the CEL says it needs to be replaced,,,,,,,can someone point out where i drain the coolant from?
If you are wanting to drain the coolant completely there should be a plastic screw at the bottom right or left of your radiator.
Here are instructions on flushing the radiator. Steps 3 - 5 talks about the screws/plugs
Park the car on a level surface. To make flushing the radiator in a Chevy Cobalt easier, you may want park the auto on risers to elevate the front end of the Cobalt.
Open the hood and prop it up securely. Touch the radiator to make sure it is cool to the touch. A hot radiator can explode due to internal pressure and cause burn injuries.
Turn the radiator cap one turn to relieve any pressure. Allow a few seconds to pass, and then completely remove the radiator cap. Use waterproof work gloves to keep your hands clean and safe from injury.
Place a pan or bucket underneath the radiator drain valves located underneath the radiator. This pan or bucket should have a two-gallon capacity in order to hold the liquid.
Take a wrench and remove the radiator drain plug from the underside of the radiator.
Allow the radiator to drain completely. After completing the drain, place a cover on the bucket or pour the coolant into another sealable container. Coolant is very toxic. Take it to a local hazardous waste disposal company or to your local auto store for proper disposal.
Flush the radiator of the Chevy Cobalt out with distilled water. Tap water can leave sediments behind that can damage your coolant system. Allow the distilled water to drain into the pan and dispose of the flush solution. Repeat this process until the drained water is clear of debris.
Replace the radiator plug on the underside of the radiator.
Fill the radiator to the top with coolant recommended for the Chevy Cobalt. This coolant is available at your local Chevy dealer. The advantage to using this coolant is that it comes pre-mixed to the correct levels.
Start the auto and run it until the cooling fan turns on twice. Next, turn off the auto and check the level of the coolant. If the coolant level in the radiator retreats, refill the coolant until it is to the top of the radiator. Put the radiator cap back in place and close the hood.
Read more: How to Flush the Radiator in a Chevy Cobalt | eHow.com http://www.ehow.com/how_4454088_flus...#ixzz0xov6CX9m