Cooling System: Service and Repair

WARNINGS:
^ To avoid the danger of being burned, do not remove the radiator fill cap while the engine and radiator are still hot. Scalding fluid and steam may be blown out under pressure.

^ Under some conditions, ethylene glycol based in engine coolant is flammable. To avoid being burned when adding engine coolant, do not spill it on the exhaust system or on hot engine parts.

CAUTIONS:
^ Dispose of or store 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! If your state/local environmental enforcement group does not allow the discharge of coolant there are various methods and equipment that can be used to flush the coolant system. If using special equipment such as a back flusher, follow the manufacturer's instructions. However, the thermostat should be removed before flushing the system.

^ When adding coolant, it is important that you use DEX-COOL(R) (orange-colored, silicate-free) coolant meeting GM Specification 6277M. If silicate 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 30 000 miles (50 000 km) or 24 months.

TOOL REQUIRED FOR ENGINE COOLANT FLUSHING:
^ Non-Aqueous Coolant Exchanger such as Pro-Fill J 75010-KM (Available in the GM Dealer Equipment program)

TOOL REQUIRED FOR ENGINE COOLANT RECYCLING:
^ GM approved Recycling System such as Pro Clean (Available in the GM Dealer Equipment program)

ENGINE COOLANT RECYCLING
As the need arises to conduct cooling system maintenance or repairs, all of the used coolant must be removed and replaced with qualified new or recycled coolant. If only the radiator is drained, up to 50 percent of the used, contaminated coolant can remain in the cooling system. Removing used coolant (from the vehicle) can be accomplished by several methods:

^ Utilize waterless coolant evacuation system available in the GM Dealer Equipment program (or equivalent) which removes the used coolant and replaces it with approved new or recycled coolant.

^ Utilize a GM approved coolant recycling system available in the GM Dealer Equipment program (or equivalent) which recycles the coolant on the vehicle thereby eliminating the need for evacuation.

^ Recover used coolant and store in a used coolant holding tank and submit the used coolant for recycling on a regular basis.

DRAINING AND REFILLING PROCEDURE
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 pressure cap.
b. Wait until any remaining pressure (indicated by hissing sound) is relieved.
c. After all hissing ceases, press down on pressure cap and continue to rotate pressure 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.
6. Remove knock sensors, located on either side of engine block.
7. Allow system to drain completely.
8. Close radiator drain cock and tighten to 1.5 Nm (13 lb in).
9. Install knock sensors and tighten to 20 Nm (15 lb ft).
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. Add enough water and DEX-COOL(R) engine coolant (meeting GM specification 6277M) to provide a solution that is at least 50 percent antifreeze, but no more than 70 percent antifreeze.
a. Close air bleed vent when bubbles disappear and only coolant is visible.
b. Fill radiator to below neck.
c. Fill reservoir to "FULL HOT" mark.
d. Add two cooling system sealer pellets (GM P/N 3634621).
e. Install reservoir cap.

15. Run engine, with radiator pressure cap removed, until normal operating temperature is reached (radiator inlet hose becomes hot).
16. With engine idling, add engine coolant to radiator until level reaches bottom of neck.
17. Install pressure cap. Arrows on cap must line up with vent tube.
18. Inspect for leaks, after running engine until normal operating temperature is reached.