Draining and Filling Cooling Systems
Draining and Filling Cooling SystemDraining Procedure
Caution: Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.
1. Place a drain pan under the radiator drain cock.
2. Place the end of the tube in the drain pan.
3. After the engine cools down, remove the radiator cap.
4. Turn the drain cock counterclockwise in order to allow the coolant to drain.
5. Allow the coolant to drain from the system until the flow stops.
6. Place a drain pan under the engine block drain hole plug.
7. Remove the drain hole plug from the engine block.
8. If equipped with the 4.3L, remove the drain hole plug from the engine block.
9. If equipped with the 5.0L and 5.7L, remove the drain hole plug from the engine block.
10. If equipped with the 6.5L, remove the drain hole plug from the engine block.
11. If equipped with the 8.1L, remove the drain hole plug from the engine block.
12. Allow the coolant to drain from the block until the flow stops. There may be more drainage from the radiator at this time.
13. Apply Teflon Pipe Sealant GM P/N 12346004 or equivalent to the threads of the engine block coolant drain hole plugs.
Notice: Refer to Fastener Notice in Service Precautions.
14. Install the engine block coolant drain hole plugs.
^ Tighten the 4.3L, 5.0L, 5.7L and 8.1L engine block drain hole plugs to 20 Nm (15 ft. lbs.).
^ Tighten the 6.5L engine block drain hole plugs to 25 Nm (18 ft. lbs.).
15. Close the radiator drain cock.
Filling Procedure
Notice: Refer to Coolant Addition Notice in Service Precautions.
1. Inspect to make sure that the radiator drain cock is closed.
2. Inspect to make sure that the block drain hole plug is tight.
3. Add the DEX-COOL to the radiator, then add clean drinkable water to the cooling system. If you use the old coolant, make sure the solution is clean and clear, and that the solution is a 50/50 mixture of glycol and water.
4. Place a large top funnel in the radiator filler neck or surge tank.
5. Slowly pour in the coolant. Because the thermostat is closed, filling the cooling system may be slow.
6. Using the following procedures, bleed the air from the engine cooling system.
6.1. Remove the cap from the surge tank.
6.2. Remove the bleed screw (slotted) from the top of the thermostat housing.
6.3. Pour coolant into the surge tank, and watch for coolant flowing from the bleed screw.
6.4. When a constant flow of coolant is reached, closed the bleed screw at the top of the thermostat housing.
6.5. Continue to fill the surge tank to the proper level.
6.6. Install the cap on the surge tank.
7. After filling the cooling system to 13 mm (0.5 inch) below the radiator filler neck (4.3L, 5.0L, and 5.7L) or to the full mark on the surge tank (6.5L, 8.1L), start the engine and let the cooling system warm up. When the thermostat opens, the coolant level may drop. If the level drops, add coolant as necessary.
8. Install the radiator or surge tank cap.
9. Inspect the coolant level in the coolant recovery reservoir (4.3L, 5.0L, and 5.7L) or the surge tank (6-5L, 8.1L). Add coolant as necessary.