Cooling System Draining and Filling L26, L32

Tools Required

J 26568 Coolant and Battery Tester

Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

Important: Draining the cooling system with the pressure cap installed will syphon the coolant from the overflow tank.

1. Remove the coolant pressure cap.
2. Place a drain pan under the drain cock.
3. Open the radiator drain cock.
4. Drain the cooling system.
5. If a complete engine block drain is required for the L26 or L32 engine, remove the knock sensors. Refer to Knock Sensor 1 Replacement and Knock Sensor 2 Replacement in Engine Controls - 3.8L.
6. Inspect the coolant.
7. Follow the appropriate procedure based on the condition of the coolant.

•	Normal in appearance--Follow the filling procedure.

•	Discolored--Follow the flush procedure. Refer to Flushing .

Notice: Refer to Fastener Notice in the Preface section.

Notice: The procedure below must be followed. Improper coolant level could result in a low or high coolant level condition, causing engine damage.

1. Close the radiator drain cock.
2. If the engine block was drained for the L26 or L32 engine, install the knock sensors. Refer to Knock Sensor 1 Replacement and Knock Sensor 2 Replacement in Engine Controls - 3.8L.
3. Open the cooling system bleeder screw.

Important: Use a 50/50 mixture of DEX-COOL antifreeze and clean, drinkable water.

4. Slowly fill the cooling system with a 50/50 coolant mixture. Refer to Approximate Fluid Capacities .
5. After the coolant is visible and stable at the filler neck, push down on the upper radiator hose to remove air. While pushing down on the upper radiator hose ensure that the filler neck is full of coolant.
6. Close the cooling system bleeder screw.
7. Release the upper radiator hose and add coolant to the filler neck.
8. Push down on the radiator hose and try to move any air in the upper hose back to the radiator. Repeat this step three times and add coolant to the filler neck each time.
9. Install the coolant pressure cap.
10. Fill the coolant recovery bottle to the indicator line.
11. Start the engine.
12. Run the engine at 2,500 RPM until the engine is hot enough to open the thermostat.
13. Allow the engine to idle for 3 minutes.
14. Shut the engine OFF.
15. Allow the engine to cool.
16. Top off the coolant as necessary.
17. Inspect the concentration of the engine coolant using the J 26568 .
18. Rinse away any excess coolant from the engine and the engine compartment.

Cooling System Draining and Filling LS4

Tools Required

J 26568 Coolant and Battery Tester

Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

Important: Draining the cooling system with the pressure cap installed will syphon the coolant from the overflow tank.

1. Remove the coolant pressure cap.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
3. Place a drain pan under the drain cock.
4. Open the radiator drain cock.
5. Drain the cooling system.
6. If a complete engine block drain is required for the LS4 engine, remove the drain plugs. Refer to Draining Fluids and Oil Filter Removal for the 5.3L engine.
7. Inspect the coolant.
8. Follow the appropriate procedure based on the condition of the coolant.

•	Normal in appearance--Follow the filling procedure.

•	Discolored--Follow the flush procedure. Refer to Flushing .

Notice: Refer to Fastener Notice in the Preface section.

1. Close the radiator drain cock.
2. If a complete engine block drain is required for the LS4 engine, install the drain plugs. Refer to Draining Fluids and Oil Filter Removal for the 5.3L engine.
3. Lower the vehicle.

Important: Use a 50/50 mixture of DEX-COOL antifreeze and clean, drinkable water.

4. Slowly fill the cooling system with a 50/50 coolant mixture until the coolant level is visible and stable.
5. Install the pressure cap loosely (threaded on about one turn).
6. Start the engine and raise the engine speed to 2500 RPM and hold it there for 40 seconds, then shut engine off.
7. Remove the pressure cap and fill the coolant system until the level is visible and stable.
8. Install the pressure cap loosely (threaded on about one turn).
9. Start the engine and raise the engine speed to 2500 RPM and hold it there for 30 seconds, then shut engine off.
10. Remove the pressure cap and fill the coolant system until the level is visible and stable.
11. Install the pressure cap loosely (threaded on about one turn).
12. Start the engine and raise the engine speed to 2500 RPM and hold it there for 20 seconds, then shut engine off.
13. Remove the pressure cap and fill the coolant system until the level is visible and stable.
14. Install the pressure cap, fully threaded on.
15. Fill the coolant recovery bottle to the indicator line, then add 400  milliliters (13.5  ounces) more.
16. Start the engine and run it above 2500 RPM until it is hot enough to open the thermostat, this will allow the trapped air to be purged from the engine.
17. Complete a series of three, four-second-duration idles with four-second-duration 3000 RPM cycles.
18. Turn the engine off and allow it to cool down.
19. Fill the coolant recovery bottle to the indicator line.
20. Inspect the concentration of the engine coolant using the J 26568 .
21. Rinse away any excess coolant from the engine and the engine compartment.