Cooling System: Service and Repair

1. Park vehicle on 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 heater air bleed vents located just above water pump on the thermostat housing and heater outlet hose pipe. Air bleed vents should be open two or three turns.
^ Place a shop towel under the bleed valve to prevent coolant from splashing onto distributor.
6. Remove the engine block coolant drain hole plug and knock sensor, located on either side of engine block.
7. Allow coolant system to drain completely.

NOTE: Dispose of 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 the knock sensor, and engine block coolant drain hole plug. Tighten radiator drain cock to 1.5 Nm (15 inch lbs.). Knock sensor to 19 Nm (14 ft. lbs.). Engine block coolant drain hole plug to 18 Nm (13 ft. 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 below neck.

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

c. Fill coolant recovery reservoir to "FULL HOT" mark.
d. Add two cooling system sealant pellets GM P/N 3634621.
e. Install coolant recovery reservoir cap.
15. Run engine, with 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 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.

NOTICE: The "LOW COOLANT" warming/indicator lamp may come on after this procedure. After operating vehicle so engine heats up and cools down three times, if "LOW COOLANT" warning/indicator lamp does not go out, or fails to come on at ignition check, and coolant is above "FULL COLD" mark in reservoir, See Instrument Panel, Gauges and Warning Indicators. If at any time the "TEMP" warning/indicator lamp comes on, immediate action is required. Turn off engine and allow vehicle to cool. Do not remove radiator pressure cap at this time.