1. Place a drain pan under the radiator drain cock.
2. Install a tube on the drain cock.
3. Place the end of the tube in the pail or pan.
4. Make sure the cooling system is cool, then remove the radiator cap.
5. Open the drain cock completely.
6. Let the cooling system drain until the flow stops.
7. Place a drain pan under the engine.
8. Remove the drain plug in the engine block.
9. Let the engine block drain until the flow stops.
• There may be more drainage from the radiator at this time.
10. Replace the engine block drain plug.
11. Close the radiator drain cock.

Filling (Gasoline Engines)
NOTICE : Two sealant pellets GMSPO part no. 3634621 m ust be added to’ the radiator when­ ever the coolant system is drained and refilled with fresh coolant Failure to use the correct sealant pellets may result in premature coolant pump leakage. Do not add the pellets to the coolant recovery bottle since
this may prevent the ‘coolant. system from operating property. Do not add the sealant pellets to the diesel cooling system due to the unique coolant pump shaft seal.
1. Check the radiator drain cock to be sure it is closed.
2. Check the engine drain plug to be sure it is tight.
3. Premix the antifreeze with clear water in 50/50 mix­ture.
• If the old coolant is being used, check it for glycol/water mix of 50/50.
4. Place a large top funnel in the radiator fill hole.
5. Slowly pour in the coolant. The filling may be slowed because of the thermostat being closed.
6. After the cooling system is filled to 1/2 inch below the fill hole, 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 until the level is up to the fill hole.
7. Replace the radiator cap.
8. Check the coolant level in the recovery tank. Add coolant if needed.

Filling (Diesel Engines)
1. Open the air bleed valve in the engine coolant out­let (thermostat housing).
2. Fill the surge tank bottle until coolant comes out of the air bleed valve.
3. Close the air bleed valve and install the pressure cap on the surge tank.

4. On vehicles with a rear heater, close the air bleed valve. Start the engine and bring the engine speed to 2000 RPM for 2 to 3 minutes to flush any air for the rear heater. Shut the engine off and reopen the air bleed valve. Fill the surge tank until coolant comes out the air bleed valve. Close the air bleed valve and install the pressure cap on the surge tank.

5. Monitor the cold coolant level in the surge tank.
Add coolant as needed to bring the coolant level to the “Full Cold” mark.


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