When adding or changing the fluid in the system, create a 50/50 mixture of high quality ethylene glycol antifreeze and water.
See Figure 1
The fluid level may be checked by observing the fluid level marks of the recovery tank. The level should be between the FULL HOT and FULL COLD mark when the system is at normal operating temperature. When the engine is cold, the fluid level should be above the FULL COLD mark on the reservoir. At normal operating temperatures, the level should be between the ADD and the FULL marks. Only add coolant to bring the level to the FULL mark.
DRAINING AND REFILLING
See Figures 2 through 8
- With a cool engine, slowly rotate the radiator cap counterclockwise to the detent without pressing down on the cap.
- Wait until any remaining pressure is relieved by listening for a hissing sound.
- After all the pressure is relieved, press down on the cap and continue to rotate the radiator cap counterclockwise.
- With a suitable container to catch the fluid under the radiator, open the radiator drain cock.
- If equipped, remove the engine block drain plugs and the knock sensor, located on either side of the engine block. This will help to drain the coolant from the block.
- Loosen or slide the recovery tank hose clamp at the radiator filler neck overflow tube and remove the hose. Holding the hose down to the drain pan, allow the recovery tank to empty. Attach the hose to the filler neck overflow and tighten the clamp.
- Close the radiator drain cock and install the engine block drain plug and knock sensor. Tighten the knock sensor to 14 ft. lbs. (19 Nm), the engine block drain plug to 15 ft. lbs. (21 Nm), and the drain cock to 13 inch lbs. (1.5 Nm).
- Add enough coolant mixture to fill the system to a level just below the radiator neck. Fill the reservoir assembly to the "FULL COLD" mark.
Fill the cooling system with a 50/50 mixture of water and Ethylene Glycol antifreeze. Freezing protection should be appropriate for temperatures of -34°F (-37°C). When filling the coolant system, add two cooling system sealer pellets (GM part no. 3634621 or equivalent).
- Firmly set the parking brake. Run the engine with the radiator cap OFF, until normal operating temperature is reached.
- With the engine idling, add engine coolant to the radiator until the level reaches the bottom of the radiator fill neck. Install the cap assembly. When installing the cap, make sure that the arrows on the cap line up with the overflow tube.
Never add cold water to an overheated engine.
- Add coolant to the recovery tank, as necessary.
- After filling the radiator and recovery tank, run the engine until it reaches normal operating temperature, to make sure that the thermostat has opened and all the air is bled from the system.
FLUSHING AND CLEANING THE SYSTEM
See Figure 8
The cooling system should be drained, thoroughly flushed and refilled at least every 30,000 miles or 24 months. This operation should be done with the engine cold.
- Drain the cooling system as described earlier in this section.
- Fill the cooling system with warm water and start the engine. Run the engine until normal operating temperature is reached.
- At this point, turn the engine off and again drain the cooling system.
- Repeat this procedure until the fluid draining from the system is nearly colorless.
- Remove, empty and reinstall the coolant recovery reservoir assembly.
- Fill the cooling system with a 50/50 mixture of ethylene glycol antifreeze, as outlined in the previous procedure.