How To Change Radiator Coolant On Chevy Cobalt

How to change the radiator coolant on a Chevrolet Cobalt is not your normal procedure as done on older vehicles, so follow correct procedure. The radiator coolant drain petcock is located on the bottom corner of the radiator on the passenger side of the vehicle. If you turn the petcock and open the valve, the radiator coolant will drain out of the drain hole on the bottom passenger side of the radiator. To open it, turn it counterclockwise 1-2 full turns to start draining, or keep turning to remove the drain valve completely. You may have to use a pair of pliers to turn the valve, as may be to hard to turn by hand. Be careful the drain valve is only plastic. Make sure you have a big bucket to catch the coolant in or you will be making a huge mess, also have some rags on hand to wipe up any mess.

The cobalt uses ONLY DEX-COOL extended life radiator coolant and cannot be mixed with the regular green anti-freeze radiator coolant, as will form an acid that is very damaging to your cooling system. Looking into my 2006 Cobalt Owner’s Manual it states that DEX-COOL is designed to remain in your Cobalt for five years or 150,000 miles (240,000 km) or whichever occurs first. Must be a 50/50 mixture of DEX-COOL and clean drinking water. DEXCOOL is known to jell up and do other strange damaging stuff to all your internal components (engine, heater core, radiator) if not changed on a regular scheduled maintenance.

Chevy Cobalt Radiator Coolant Drain Steps:

  1. Make sure vehicle coolant is not hot before draining.
  2. You will need to lift the front end up (put up on a ramp or car jacks)
  3. Place a large drain bucket or pan under the radiator drain petcock on bottom of radiator, on passenger side of car.
  4. Remove the top off the surge tank/coolant fill bottle in engine compartment.
  5. Turning the rad drain petcock counterclockwise 1-2 full turns to start draining radiator fluid.
  6. When done draining the radiator replace and hand tighten the petcock/drain valve.

Chevy Cobalt Radiator Coolant Fill Procedure:

There are two ways to fill the radiator. The first procedure is to take the upper radiator hose off and pour the radiator coolant in until the radiator is full. Then you replace the radiator hose and fill the coolant surge tank bottle to the correct level (cold fill line). Now start the car open your heater to full and let it run until it is hot, the radiator fans will kick on about 220F – 230F. Now turn the vehicle off and let it cool down. When cooled down for a bit, you then top off the overflow bottle to the correct level.

The second procedure to fill the radiator is to just fill the surge tank bottle to the correct level then close lid, start the car, open your heater to full and let it run until it is hot. The radiator fans will kick on about 220F – 230F when hot air blows from your car heater, you know the coolant is circulating and thermostat is open. While vehicle is running hold throttle open at about 2000 RPM for a few minutes then idle for 30 seconds, shut vehicle off let cool. Open surge tank bottle when cooled, add more DEX-COOL coolant to correct level. Surge tank bottle lid still off, Squeeze the top radiator hose gently to push trapped air out of the system, close surge tank bottle lid. You will have to repeat this whole procedure a few times to get all the air out of the system and coolant re-filled properly.

You should be fine to drive the car at this point, but make sure after heating up the car again check the coolant level in the surge tank bottle as you may need to top it off again, so keep some extra coolant handy.


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