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. This is done by removing the radiator cap, on models without an expansion tank, and seeing that the coolant is within two inches of the bottom of the filler neck. On models with an expansion tank, if coolant visible above the MIN mark on the tank, the level is satisfactory. Always be certain that the filler caps on both the radiator and the reservoir are tightly closed.
In the event that the coolant level must be checked when the engine is warm on engines without the expansion tank, place a thick rag over the radiator cap and slowly turn the cap counterclockwise until it reaches the first detent. Allow all the hot steam to escape. This will allow the pressure in the system to drop gradually, preventing an explosion of hot coolant. When the hissing noise stops, remove the cap the rest of the way.
If the coolant level is low, add equal amounts of ethylene glycol based antifreeze and clean water. On models without an expansion tank, add coolant through the radiator filler neck. Fill the expansion tank to the MAX level on cars with that system.
If the coolant level is chronically low or rusty, refer to the Troubleshooting information for diagnosis of the problem.
The radiator hoses and clamps and the radiator cap should be checked at the same time as the coolant level. Hoses which are brittle, cracked, or swollen should be replaced. Clamps should be checked for tightness (screwdriver tight only. Do not allow the clamp to cut into the hose or crush the fitting). The radiator cap gasket should be checked for any obvious tears, cracks or swelling, or any signs of incorrect seating in the radiator neck.
DRAIN & REFILL
Once every 24 months or 24,000 miles, the cooling system should be drained, thoroughly flushed, and refilled. This should be done with the engine cold.
- Remove the radiator cap.
- There are usually two drain plugs in the cooling system; one at the bottom of the radiator and one at the rear of the driver's side of the engine. Both should be loosened to allow the coolant to drain.
- Turn on the heater to its hottest position. This ensures that the heater core is flushed out completely. Flush out the system thoroughly by refilling it with clean water through the radiator opening as it escapes from the two drain cocks. Continue until the water running out is clear. Be sure to clean out the coolant recovery tank as well if your car has one.
- If the system is badly contaminated with rust or scale, you can use a commercial flushing solution to clear it out. Follow the manufacturer's instructions. Some causes of rust are air in the system, caused by a leaky radiator cap or an insufficiently filled or leaking system; failure to change the coolant regularly; use of excessively hard or soft water; and failure to use a proper mix of antifreeze and water.
- When the system is clear, allow all the water to drain, then close the drain plugs. Fill the system through the radiator with a 50/50 mix of ethylene glycol type antifreeze and water.
- Start the engine and top off the radiator with the antifreeze and water mixture. If your car has a coolant recovery tank, fill it half full with the coolant mix.
- Replace the radiator and coolant tank caps, and check for leaks. When the engine has reached normal operating temperature, shut it off, allow it to cool, then top off the radiator or coolant tank as necessary.