Cooling System: Service and Repair

1. Park vehicle on a level surface.
2. Remove coolant recovery reservoir fill cap.
3. Remove radiator pressure cap.
a. Slowly rotate cap counterclockwise until it reaches the "stop." Do not press down while turning the radiator pressure cap.
b. Wait until any remaining radiator pressure (indicated by a hissing sound) is relieved.
c. After all hissing ceases press down on the radiator pressure cap and continue to rotate cap counterclockwise.
4. Open radiator drain cock.
5. Open air bleed vent located on the top of the water outlet. Air bleed vent should be open two or three turns.
^ Place a shop towel under the bleed valve to prevent coolant from splashing onto the EGR valve outlet pipe.
6. Remove knock sensors located on either side of engine block.
7. Allow coolant system to drain completely.

NOTE: Dispose if used coolant in a proper fashion, i.e., in a used coolant holding tank. NEVER POUR USED COOLANT DOWN THE DRAIN! Ethylene glycol based engine coolant is a very toxic chemical; disposing of it into the sewer system or ground water is both illegal and ecologically unsound!

8. Close radiator drain cock.
9. Install knock sensors.
^ Knock sensors to 19 Nm (14 ft. lbs.).
^ Radiator drain cock to 1.5 Nm (13 inch lbs.).
10. Add enough water to fill cooling system.
11. Run engine until thermostat opens.
12. Stop engine. Repeat steps 2 through 10, until drained fluid is nearly colorless.
13. Remove, clean and reinstall coolant recovery reservoir.
14. Fill cooling system.
a. Close air bleed vent when bubbles disappear and only coolant is visible.
b. Fill radiator to just below the radiator fill neck.

NOTE: When adding coolant, it is important that you use DEX - COOL coolant meeting GM Specification 6277M.

c. Fill coolant recovery reservoir to the "FULL HOT" mark.
d. Add two cooling system sealer pellets GM P/N 3634621.
e. Stall coolant recovery reservoir cap.
15. Run the engine, with the radiator pressure cap removed, until normal operating temperature is reached (radiator inlet hose becomes hot).
16. With the engine idling, add enough engine coolant to the radiator until the coolant level reaches the bottom of the fill neck.
17. Install the radiator pressure cap.
^ Arrows on cap must line up with vent tube.
^ Inspect for leaks, after running engine until normal operating temperature is reached.