General Motors recommends that you check your cooling system every 12 months or 15,000 miles (24,100 km). The following services should be performed:
- Wash and inspect the radiator cap and the filler neck.
- Check the coolant level and the degree of freezing protection.
- If a pressure tester is available, pressure test the system and the radiator cap.
- Inspect the hoses of the cooling system. Expect to replace the hoses at 24 months/30,000 miles (48,200 km).
- Check the fins of the radiator for blockage.
See Figure 1
The coolant used in any General Motors engine must:
On diesels, this proportion can be accurately attained only when refilling the system entirely. See Draining and Refilling.
The use of self-sealing coolants is not recommended. Also, the use of a coolant meeting the above requirements negates the need for supplemental additives. Use of such supplemental products is an unnecessary expense and may cause less than optimum cooling system performance.
See Figure 2
Any time the hood is raised, check the level of the coolant in the see-through plastic coolant recovery tank. With the engine cold, the coolant level should be near the ADD mark on the tank. At normal engine operating temperature, the level should be at the FULL mark on the bottle. If coolant must be added to the tank, use a 50/50 mix of coolant/water to adjust the fluid level on models with gasoline engines. On models with diesel engines, use straight, undiluted coolant to adjust the level in the tank.
An inexpensive tester may be purchased to test the freezing protection of the coolant. Follow the instructions provided with the tester. The coolant used in models with gasoline engines should protect to -34°F (-37°C); diesels must have protection to -75°F (-59°C).
DRAIN & REFILL
At least every 24 months or 30,000 miles (50,000 km)-whichever comes first. The cooling system should be completely drained and refilled with the proper mixture of coolant and water. Many mechanics recommend that this be done once a year for extra protection against corrosion and subsequent overheating.
Though most coolants are labeled permanent, this only means that the coolant will retain its anti-freezing characteristics. The required rust inhibitors and other chemicals which were added to the coolant during its manufacture will become less effective over a period of time.
If you are only replacing the hoses, perform steps 1-3, and 11-16 as required.
- Park the car a level surface.
- Remove the radiator cap. Slowly rotate the pressure cap counterclockwise to detent. Wait until the pressure (indicated by a hissing sound) is completely gone.
- After the pressure is relieved, press down on the cap and continue to rotate counterclockwise.
- Raise the front of the vehicle and support it safely with jackstands.
- Place a drain pan under the car to collect the drained coolant.
- Open the radiator fitting (located at the bottom of the radiator) by turning it counterclockwise. It may be wise to coat the fitting with penetrating lubricant before you attempt to turn it. Allow the coolant to drain from the radiator.
- On the 3.1L engine open the air bleed vent on the throttle body return pipe (above the coolant pump). The air bleed vent should be opened two to three turns.
- Remove the drain plug(s) from the engine block (located on the engine block, above the engine oil pan) and allow the coolant to drain.
- Close the radiator drain fitting and reinstall the engine block plugs.
- On the 3.1L close the bleed valve on the throttle body.
- Add clear water to the system until it is filled.
- Start the engine and repeat steps 7-12 until the drained water is almost colorless. Turn the engine OFF .
- Allow the system to drain completely and repeat step 10. Remove the cap from the coolant recovery tank, leaving the hoses connected to the cap.
- Unbolt and remove the coolant recovery tank, drain it, and flush it with clear water. Reinstall the tank.
- Fill the radiator to the base of the radiator filler neck with a 50/50 mixture of coolant/water. On diesel equipped models, add a gallon of undiluted coolant first, then add the 50/50 solution.
If only the radiator was drained, use a 50/50 solution to refill it, then check the freezing protection after the level stabilizes.
- Fill the coolant recovery tank to the FULL mark with the 50/50 solution.
- With the radiator cap still removed, start the engine and allow it to idle until the upper radiator hose becomes hot, indicating that the thermostat has opened.
- With the engine still idling, fill the radiator to the base of the filler neck with the 50/50 solution.
- Install the radiator cap, being sure to align the arrows on the cap with the overflow tube.
- Turn the engine OFF , check for leakage, and double check that the radiator drain is closed and the drain plug(s) is (are) tightened.
FLUSHING AND CLEANING THE SYSTEM
Several aftermarket radiator flushing and cleaning kits can be purchased at your local auto parts store. It is recommended that the radiator be cleaned and flushed of sludge and any rust build-up once a year. Manufacturer& directions for proper use, and safety precautions, come in each kit.
See Figure 3
Before removing the cap. squeeze the upper radiator hose. If it compresses easily (indicating little or no pressure in the system), the cap may be removed by turning it counterclockwise until it reaches the stop. If any hissing is noted at this point (indicating the release of pressure), wait until the hissing stops before you remove the cap. To completely remove the cap, press downward and turn it counterclockwise.
If the upper radiator hose is hard, pressure is indicated within the system. In this case, a greater degree of caution should be used in removing the cap. Cover the radiator cap with a thick cloth, and while wearing a heavy glove, carefully turn the cap to the stop. This will allow the pressure to be relieved from the system. After the hissing stops, completely remove the cap (press and turn counterclockwise).
Check the condition of the radiator cap gasket and the seal inside of the cap. The radiator cap is designed to seal the cooling system under normal operating conditions which allows the system to build-up a certain amount of pressure (this pressure rating is stamped or printed on the cap). The pressure in the system raises the boiling point of the coolant to help prevent overheating. If the radiator cap does not seal properly, the boiling point of the coolant will be lowered and overheating will occur. If the cap must be replaced, purchase the new cap according to the pressure rating which is specified for your vehicle.
Prior to installing the cap, inspect and clean the radiator filler neck. If you are reusing the old cap, clean it thoroughly with clear water. After turning the cap, make sure that the arrows on the cap align with the overflow hose.
CLEANING RADIATOR OF DEBRIS
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 needlenose pliers. Be careful, the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.