See Figure 1
Dealing with the cooling system can be a dangerous matter unless the proper precautions are observed. It is best to check the coolant level in the radiator when the engine is cold. All vehicles covered by this information should be equipped with coolant recovery tank. If the coolant level is at or near the ADD/FULL COLD line (engine cold) or the FULL HOT line (engine hot), the level is satisfactory. Always be certain that the filler caps on both the radiator and the recovery tank are closed tightly.
At least once every two years or 30,000 miles (50,000 km), the engine cooling system should be inspected, flushed and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has too much water, it won't protect against freezing.
Do not brush the radiator fins. The radiator fins are necessary for good heat transfer. Brushing damages the fins and reduces heat transfer.
The cooling system should be inspected, flushed and refilled with fresh coolant at least every 30,000 miles (48,000 km) or 24 months. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion.
When the coolant is being replaced, use a good quality antifreeze that is safe to be used with aluminum cooling system components. The ratio of antifreeze to water should always be a 50/50 mixture. This ratio will ensure the proper balance of cooling ability, corrosion protection and antifreeze protection. At this ratio, the antifreeze protection should be good to -34°F (-37°C). If greater antifreeze protection is needed, the ratio should not exceed 70% antifreeze to 30% water.
Starting with the 1996 model year, these vehicles were filled at the factory with a new type of antifreeze/coolant called GM Goodwrench DEX-COOL. A 50/50 mixture of DEX-COOL and clean water will provide all the recommended protection for 1996-98 vehicles. DO NOT use DEX-COOL in pre-1996 vehicles. DO NOT mix DEX-COOL with any other type of antifreeze.
See Figures 2 and 3
When checking the coolant level, the radiator cap need not be removed. Simply check the coolant level in the recovery bottle or surge tank.
Check the coolant level in the recovery bottle or surge tank, usually mounted on the inner fender. With the engine cold, the coolant level should be at the FULL COLD level. With the engine at normal operating temperature, the coolant level should be at the FULL HOT mark. Only add coolant to the recovery bottle or surge tank as necessary to bring the system up to a proper level.
On any vehicle that is not equipped with a coolant recovery bottle or surge tank, the level must be checked by removing the radiator cap. This should only be done when the cooling system has had time to sufficiently cool after the engine has been run. The coolant level should be within 2 inch (51mm) of the base of the radiator filler neck. If necessary, coolant can then be added directly to the radiator.
COOLING SYSTEM INSPECTION
Checking the Radiator Cap Seal
See Figure 4
While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat.
Worn caps should be replaced with a new one.Checking the Radiator for Debris
See Figure 5
Periodically clean any debris; leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.
Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful, the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not move them again.
DRAIN & REFILL
See Figures 6, 7, 8 and 9
- Make sure the engine is cool and the vehicle is parked on a level surface, remove the radiator cap by performing the following:
- Slowly rotate the cap counterclockwise to the detent.
- If any residual pressure is present, WAIT until the hissing stops.
- After the hissing noise has ceased, press down on the cap and continue rotating it counterclockwise to remove it.
- Remove the recovery bottle or surge tank cap.
- Place a fluid catch pan under the radiator. Place a 5 /16inch piece of tubing through the lower tie-bar and over the drain valve, then open the valve and drain the coolant from the system.
- Remove the engine block drain plug.
- Install the engine block drain plug, use pipe sealer on the plugs, then close the drain valve.
- Using the proper mixture of coolant, fill the radiator to the bottom of the filler neck and the coolant tank to the FULL mark.
- Install the radiator cap, making sure the arrows line up over the overflow tube leading the reservoir or surge tank. Place the cap back on the recovery bottle or surge tank.
- Start the engine. Select heat on the climate control panel and turn the temperature valve to full warm. Run the engine until it reaches normal operating temperature. Check to make sure there is hot air flowing from the floor ducts.
- Check the fluid level in the reservoir or surge tank and add as necessary.
FLUSHING & CLEANING THE SYSTEM
- Refer to the drain and refill procedure in this section, then drain the cooling system.
- Close the drain valve.
A flushing solution may be used. Ensure it is safe for use with aluminum cooling system components. Follow the directions on the container.
- Remove the thermostat. Reinstall the thermostat housing.
- Add sufficient water to fill the system.
- Start the engine and run for a few minutes. Drain the system.
A flushing solution may be used. Make sure it is safe for use with aluminum cooling system components. Follow the directions given on the container.
- If using a flushing solution, disconnect the heater hose that connects the cylinder head to the heater core (that end of the hose will clamp to a fitting on the firewall. Connect a water hose to the end of the heater hose that runs to the cylinder head and run water into the system until it begins to flow out of the top of the radiator.
- Allow the water to flow out of the radiator until it is clear.
- Reconnect the heater hose.
- Drain the cooling system.
- Reinstall the thermostat.
- Empty the coolant reservoir or surge tank and flush it.
- Fill the cooling system, using the correct coolant, to the bottom of the filler neck. Fill the reservoir or surge tank to the FULL mark.
- Install the radiator cap, making sure that the arrows align with the overflow tube.