In the 2005 model year, Chevrolet began phasing out the aging Cavalier and introduced its eventual replacement, the Cobalt. Unfortunately, it was nowhere near as successful as its predecessor, and Chevy discontinued it after just six model years. The 2007 Cobalt came standard with a 2.2-liter engine that used GM’s proprietary Dex-Cool coolant to keep it within an acceptable temperature range. Chevy recommended flushing and refilling the 2.2-liter engine's cooling system every 60 months or 150,000 miles, whichever came first. Flushing the 2007 Cobalt’s coolant is more time consuming than difficult, but the money you save makes it well worth your time.
Unscrew the cap from the coolant degas bottle slowly. If you hear a hissing sound, stop loosening the cap until the hissing sound stops. Once you remove the cap, set it in a secure location to prevent losing or damaging it.
Start the engine and allow it to idle until the upper radiator hose is hot to the touch. Shut the engine off.
Lift the front of the Cobalt with a floor jack and slide jack stands under its subframe. Lower the vehicle onto the subframe.
Slide under the passenger’s side of the vehicle and find the petcock, the radiator drain plug, on the bottom of the radiator. Position a drain pan directly under the petcock. Wrap your hand in a thick shop cloth to protect it from heat and turn the petcock counterclockwise to start the flow of coolant into the drain pan.
Close the petcock once the flow of coolant stops. Lift the vehicle off the jack stands with a floor jack and remove the jack stands. Lower the vehicle to the ground.
Trace the lower radiator outlet hose, the hose on the driver’s side of the radiator, until you reach the thermostat housing. Find where the thermostat housing connects to the water pump inlet tube assembly and trace that toward the engine. Just below where the water pump inlet tube assembly connects to the engine block is the water pump drain plug.
Position a drain pan under the water pump drain plug and loosen it with a ratchet and socket. Wrap your hand in a thick shop cloth and remove the plug by hand to drain the engine block.
Hand-tighten the water pump drain plug, then torque it to 16 inch-pounds, using an inch-pound torque wrench and socket, once the coolant stops draining from the engine block.
Pour clean water into the degas bottle until the level reaches the “Cold Fill” line. Do not install the cap onto the degas bottle.
Transfer the drained coolant from the drain pan to a clean 5-gallon bucket.
Start the engine and hold the rpm at 3,000 for three minutes after the upper radiator hose is warm to the touch to allow the water to circulate through the system.
Wait until the engine is cool to the touch, then repeat Steps 3 through 11 until only clean, colorless water comes from the radiator and engine block when you drain them.
Pour 50-50 premixed Dex-Cool coolant into the degas bottle until the level remains steady at the “Cold Fill” line. The cooling system holds a total of 1.7 to 1.85 gallons, on the 2.2-liter and 2.4-liter engines, but the exact amount needed may vary.
Tighten the cap onto the coolant degas bottle.
Start the Cobalt’s engine and hold the engine speed at 2,000 to 2,500 rpm for three minutes. Allow the engine to idle for 30 seconds, then shut the engine off.
Allow the vehicle to sit until its engine is cool to the touch and check the coolant level in the degas bottle. If needed, unscrew the cap from the degas bottle and add 50-50 premixed Dex-Cool coolant until its level reaches the “Cold Fill” line.
Take the coolant in the 5-gallon bucket to a local used automotive fluid recycler for disposal. Some auto parts stores take old coolant free of charge.
