Coolent is leaking from overflow and overheating

Add coolant to the plastic overflow tank to the full line. don't need to remove radiator cap to add coolant. if you want to take off the radiator cap, push down hard & turn to the left.

Their is no radiator cap that goes directly into radiator. if you do plan on putting barr's leak in it just put it in the coolent tank on the passenger side that is the only way.

If it doesn't over heat it's very possible that there is just too much coolant, so if it's leaking from the overflow there is no problem as that's what it's designed to do

If you added the green anti freeze to you system it will make the check coolent level light come on. Drain the system and use the extended life anti freeze and that will fix the problem.

if it's getting hot also [ i guess if its getting hot it should be leaking out the overflow tube] i would think it's a worn radiator cap or check the oil for water in it [look on dipstick for cloudy looking oil] blown headgasket.
radiator cap easy fix.
blown headgasket, mechanics expensive fix

Physically look in the radiator under the cap(if one exsist's) when cool, for coolant level, and check the valve in the cap for sticking. If air is present in the radiator it can't get out, and more coolant can't get in,(from the overflow). Either clean the cap or replace it and check that it is the CORRECT cap.

If radiator is low on coolant fill it to overflowing, replace cap, and check that coolant overflow is filled to the COLD line or mark. The overflow is normally where you would add coolant. (never overfill the overflow)After refilling as outlined above, check the level every morning for 2 or 3 days until coolant level stops dropping below the cold mark and add coolant to the overflow ONLY. Do not open the radiator cap. Also, if you have even a tiny coolant leak anywhere in the system, air will get drawn in, instead of coolant from the overflow.

For more OVERHEATING PROBLEMS try these...
Radiator fins dirty, clean with a strong stream of water, not high pressure water.
Radiator clogged, try backflushing it, or replace.
Thermostat stuck open or shut, replace it.
Water pump worn out, can no longer move enough coolant, replace it.
Fan shroud broken or missing....
Electric Fan(s) not working, Check the fan, relay, fuse and engine temperature sensor's.
Belt driven fan, belt slipping, fan clutch is bad, fan blades have flattened out.
Air dam under front bumper is gone, loose, or broken. It actually has a purpose other than scraping on the driveway or curbs. It forces air up into and thru the condenser and radiator. If it's loose, airflow can actually push it out of place making it useless or blocking the airflow. Along with that, there may also be a plastic piece attached to the bottom of, and wraps up behind the bumper. If it

You are describing a slow coolant leak and the resultant no heat and blockoverheating symptoms. The no heat is because there is insufficient coolant to cycle through the heater core, and the chuggin you describe is the engine indicating serious overheating.
With engine cold, you must add water--not anti-freeze--to the radiator itself, until it reaches the top of the radiator, then start the engine. If you do not have a radiator cap in addition to the overflow bottle (some vehicles don't), you must still add water to the radiator, even if you have to bypass the overflow bottle hose to do it. Add water until no more will go into the radiator. Start engine, let idle until operating temperature is reached. Thermostat should open and a good bit of the water will "sink" into the depth of the radiator. If you have no radiator cap, observe the temperature guage. When it reaches normal operating temp, when the thermostat opens, the temp will drop briefly at first, and you will notice warm air from the heater/defroster.
Once engine is warm and known to be full of water, seal radiator cap and/or system, and let idle for 30 minutes. Use this time to locate the "mystery leak." They can be very hard to find, and some won't leak until after the engine is turned off. During this idle period, observe the vehicle exhaust from the tailpipe as well as looking for actual water leaks: sometimes a bad head gasket can be diagnosed this way; if the exhaust is white and thick like steam, and smells like anit-freeze, you have a more serious problem. It is possible that after the repeated overheating cycles you have endured you may now have both a "mystery leak" and a blown head gasket.
Once leak is located, your next step is to let engine cool completely, drain the water, fix the leak, and then and only then add new antifreeze of the proper rating and ratio recommended by Chevy for your vehicle.
Anytime you drain a cooling system and refill it, it is necessary to check the overflow bottle at least 3 times in the first week after repair to ensure that you have the proper coolant level, and have not either missed another leak or not correctly repaired one. You MUST check it before you drive the vehicle the second time after the first repair attempt because it is normal to need to add more coolant than you added initially after the repair because of air trapped in the cooling system that will only be expelled after the first start/stop heating cycle. If after 1 week of daily normal driving you have only added a little more coolant once, and there are no more problems, you can be very comfortable that you have fixed your car.

No, you can't add too much coolant. Rather, it does not hurt anything if you do. Did you add it to the radiator, or to the overflow tank?

Let it cool, then remove the radiator cap, and if needed, add coolant to the radiator. Put the cap back on, and fill the overflow tank to the "full - cold" line. Start it and run it a few minutes and look for leaks. If you find no leaks, drive it for a day or two, then let it cool and check it again. If it is down a lot (without overheating), you have a leak somewhere. If you lose enough coolant, that will make it overheat. However, if it overheats, that can cause loss of coolant, when you stop the car, you will see steam and smell coolant, and often hear it boiling.

If it overheats again, make note of when it happens: driving on the highway, or stop-and-go around town. Overheating on the highway usually indicates a clogged radiator, while in-town overheating usually indicates a bad cooling fan (you don't need the fan above about 30 MPH). A bad fan is usually the fan relay, but it can be the fan thermostat (different from the engine thermostat), or a bad fan motor.

Your system does not have a cap on the radiator. It is a 'sealed system' with the reservoir holding pressure. This is not so much an 'overflow' tank like some systems, but an expansion tank.

You can add the stop leak directly into the tank.

if you have a blown head gasket you would have a miss
the waterpump can look good and still be bad
after you replace the thermostate fill the radiator and leave the cap off start the car let it get too operating temp and check for flow if you have good flow shut the car off and and put a pressure terter on the raidator this will tell of and leaks