Caution: With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.

Caution: Under some conditions, the ethylene glycol engine coolant is combustible. In order to help avoid being burned, do not spill the antifreeze or the coolant on the exhaust system or the hot engine parts.

Notice: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

Before you drain and refill the cooling system, inspect the system. Perform any service needed to ensure that the system is clean, does not leak, and is in proper working order.

Some coolant manufacturers mix other types of glycol into their coolant formulations. Propylene glycol is the most common new ingredient. However, do not use propylene glycol in GM vehicles that were manufactured with Dex-Cool coolant.

A hydrometer does not always provide a correct measurement of freeze protection when anything other than ethylene glycol and water is being tested. The degree of inaccuracy varies depending on the proportion of other glycols present in the coolant.

Hydrometers test the amount of glycol in a mixture by measuring the specific gravity of the mixture: the more ethylene glycol, the higher the float balls go, and the better the freeze protection. Because ethylene glycol and propylene glycol do not have the same specific gravities, hydrometer readings of mixtures containing propylene glycol give incorrect values. Use a refractometer when you test coolant. Refractometers test the amount of glycol in a coolant mixture by measuring the speed of light as the light passes through the fluid, and is not affected by the specific gravity of the glycol.

For proper coolant testing, refer to Coolant Concentration Testing

1. Park the vehicle on a level surface.
2. When the engine is cool, remove the surge tank cap using the following procedure:

•	Slowly rotate the cap counterclockwise about a 1/4 turn and then stop.

•	Wait until any residual pressure (indicated by a hissing sound) is relieved.

•	After all hissing stops, continue to rotate counterclockwise until the cap is removed.




3. Insert a piece of 5/16 inch fuel line tubing, or equivalent, through the lower tie bar. Attach the hose over the radiator drain tube.



4. Open the radiator drain valve located at the bottom of the radiator tank.

For procedures requiring the cooling system to be partially drained, opening the radiator drain cock provides sufficient draining. No further actions should be required.

5. Remove the engine block drain plug.

Notice: Dispose of used engine coolant in the proper manner, such as in a used engine coolant holding tank. DO NOT POUR USED ENGINE COOLANT DOWN A DRAIN! Ethylene glycol antifreeze is a very toxic chemical. Do not dispose of coolant into the sewer system or ground water. This is illegal and ecologically unsound.

6. Remove the engine block drain plug.
7. Allow the coolant to drain completely.
8. Inspect the drained coolant.

•	If the coolant is discolored, flush the cooling system. Refer to Flushing .

•	If the coolant appears normal, continue with the filling procedure.

Notice: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

1. Close the radiator drain cock.



2. Remove the drain.
3. Install the engine block coolant drain plugs, if these were removed. Use pipe sealer, GM P/N 12346004, on the plugs.
4. Fill the surge tank to the base of the filler neck.

Important: On vehicles equipped with the 3.1L engine: Open the coolant air bleed valve on the top of the thermostat bypass pipe/heater pipe assembly. Once a continuous stream of coolant is expelled from the valve, close the valve.

5. With the pressure cap off, start the engine and let it run until the upper radiator hose starts to get hot.



6. If the coolant level in the surge tank is low, add the proper mix of coolant until the level reaches Split Line.
7. Install the surge tank pressure cap (3) onto the surge tank with hand tight pressure.
8. After servicing the cooling system, an intermittent low coolant lamp may illuminate during extreme driving maneuvers. In order to eliminate this condition, remove the surge tank cap and add coolant to a level at or above the split line of the tank when the system is cold.