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.

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. Park the vehicle on a level surface.
2. Follow the steps below to remove the surge tank fill cap:

•	Slowly rotate the cap counterclockwise.

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

•	After all hissing stops, continue turning the cap counterclockwise and remove the cap.

3. Install a piece of 3/8 inch non-reinforced hose to the drain cock outlet under the vehicle.

The hose will direct the flow of coolant into a catch basin

4. Open the radiator drain cock.

To aid in the draining the cooling system, disconnect the throttle body heater return hose (leading to the reservoir from the throttle body).

5. Allow the system to drain completely.
6. Plug the throttle body coolant return fitting and use low pressure shop air to apply a small amount of pressure (3-4 psi) to the throttle body coolant return hose. This will slightly pressurize the cooling system to aid in the removal of coolant from the engine block.
7. Inspect the condition of the engine coolant:

•	Discolored -- follow the flushing procedure below.

•	Normal in appearance -- Continue with the next step.

8. Close the radiator drain cock and remove the drain hose.
9. To aid in filling the cooling system, leave the throttle body coolant return hose disconnected until the cooling system is filled to approximately 80 percent capacity.
10. Fill the cooling system with a 50/50 concentration of clean water and GM Goodwrench® DEX-COOL®.
11. Connect the throttle body coolant return hose.
12. Top off the coolant to the KALT/COLD mark (seam on the surge tank).
13. Install radiator surge tank cap.
14. Idle the engine for 1 minute.
15. Cycle the RPM, idle to 3000, in 30 seconds intervals until engine coolant reaches 99°C (210°F).

The cooling system will bleed automatically during warm-up.

16. Shut off the engine.
17. Inspect the level of coolant and top off as necessary.
18. Wipe up any spilled coolant.