Draining, Flushing and Filling

NOTE: Before draining the cooling system, inspect the system and perform any necessary service to ensure that it is clean, does not leak, and is in proper working order. The Engine Coolant Level (ECL) should be between the LOW and FULL lines when engine is cold. If low, check for leakage and add coolant up to the FULL line. There should not be any excessive deposit of rust or scales around the radiator cap or radiator filler neck, and the coolant should also be free from oil. Replace the coolant if excessively dirty.

WARNING: To avoid the danger of being burned, do not remove the radiator cap while the engine and radiator are still hot. Scalding fluid and steam can be blown out under pressure, possibly causing personal injury.

1. Remove radiator cap when engine is completely cool. 2. Completely drain the cooling system by opening the drain plug at the bottom of the radiator and removing the cylinder block drain plug.

WARNING: Dispose of used coolant in a proper fashion, i.e., in a used coolant holding tank which is picked up along with used oil. NEVER POUR USED COOLANT DOWN THE DRAIN! Ethylene glycol antifreeze is a very toxic chemical; disposing of it into the sewer system or ground water is ecologically unsound!

3. Remove, clean and install the engine coolant recovery reservoir.
4. When all the coolant has drained, tighten the radiator drain plug.
5. Fill the cooling system with clean water.
6. Run the engine until the thermostat opens (when the coolant is circulating through the system and both radiator hoses are hot to the touch).
7. Stop engine. Repeat Steps 1 through 7 until the drained water is clear and-free of coolant and/or rust.
8. Tighten radiator drain plug.
9. Fill the cooling system with at least a 50/50 mixture of ethylene glycol antifreeze and water but not more than 70% antifreeze.
10. Fill the radiator to just below the radiator cap.
11. Fill the coolant recovery reservoir to the specified fill mark on the outside of the reservoir.

NOTE: Use ethylene glycol antifreeze meeting GM specification 1825-M to provide the required freezing and corrosion protection: -37° C (-34° F).

12. Run the engine with the radiator cap removed until normal operating temperature is reached (both radiator hoses become hot).
13. With the engine idling, add the coolant mixture until it reaches just below the radiator cap.
14. Install radiator cap; align cap ears with coolant overflow - hose.

CAUTION: Alcohol or methanol-based coolants are not recommended at any time. A solution of higher than a 70/30 mixture of antifreeze-to-water should never be used. The solution freezing point increases after this point.