Dealing with the cooling system can be dangerous matter unless the proper precautions are observed. It is best to check the coolant level in the radiator when the engine is cold. The cooling system may have, as one of its components, a coolant recovery tank. If the coolant level is at or near the 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.
In the event that the coolant level must be checked when the engine is hot and the vehicle is not equipped with a coolant recovery tank, place a thick rag over the radiator cap and slowly turn the cap counterclockwise until it reaches the first detent. Allow all 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 found to be low, add a 50/50 mixture of antifreeze and clean water. If not equipped with a recovery tank, coolant must be added through the radiator filler neck. On most models, which are equipped with a recovery tank, coolant may be added either through the filler neck on the radiator or directly into the recovery tank.
It is wise to pressure check the cooling system at least once per year. If the coolant level is chronically low or rusty, the system should be thoroughly checked for leaks.
At least once every two years or 30,000 miles (48,000 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.
The pressure cap should be examined for signs of age or deterioration. Fan belt and other drive belts should be inspected and adjusted to the proper tension. (See checking belt tension).
Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, water pump or other areas, indicate possible leakage, which must be corrected before filling the system with fresh coolant.
Whenever adding or changing fluid, use a good quality ethylene glycol antifreeze (one that will not affect aluminum), mix it with clean water until a 50/50 antifreeze solution is attained.
On most late model vehicles, the fluid level may be checked by observing the fluid level marks of the recovery tank (see through plastic bottle). The level should be near the ADD or FULL COLD mark, as applicable, when the system is cold. At normal operating temperatures, the level should be above the ADD/FULL COLD mark or, if applicable, between the ADD/FULL COLD and the FULL HOT marks. Only add coolant to the recovery tank as necessary to bring the system up to a proper level.
On any vehicle that is not equipped with a coolant recovery or overflow 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 3 in. of the base of the radiator filler neck. If necessary, coolant can then be added directly to the radiator.
COOLING SYSTEM INSPECTION
When 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
Periodically clean any debris; leaves, paper, insects, etc., from the radiator fins. Pick the large pieces 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 to move them again.
DRAIN & REFILL
- Make sure the engine is cool and the vehicle is parked on a level surface, then remove the radiator neck cap and, if equipped, the recovery tank cap in order to relieve system pressure.
- Position a large drain pan under the vehicle, then drain the existing coolant by opening the radiator drain valve (petcock). It is sometimes helpful to put a piece of vacuum hose 3 / 8 inches in diameter and about 12 in. (30 cm) long on the end of the radiator drain cock before opening the drain valve. This will help reduce some of the mess. It is also possible to drain the system by disconnecting the lower radiator hose from the bottom radiator outlet.
- Close the petcock or reconnect the lower hose. If you used it, don't forget to take the piece of vacuum hose off the valve.
- If necessary, empty the coolant reservoir and flush it. This is most easily done by removing the reservoir tank from the vehicle.
- Determine the capacity of your coolant system (see capacities specifications). Though the radiator filler neck, add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide the desired protection.
- Leave the radiator pressure cap off, then start and run the engine until the thermostat heats up and opens, this will allow air to bleed from the system and provide room for additional coolant to be added to the radiator.
- Add additional coolant to the radiator, as necessary, until the level is within 3 in. of the radiator's filler neck base.
- Stop the engine and check the coolant level.
- Check the level of protection with an antifreeze tester, then install the radiator pressure cap.
- If equipped with a coolant recovery/overflow tank, add coolant to the tank, as necessary, to achieve the proper level.
- Start and run the engine to normal operating temperature, then check the system for leaks.
FLUSHING & CLEANING THE SYSTEM
The cooling system should be drained, thoroughly flushed and refilled at least every 30,000 miles (48,000 km) or 24 months. These operations should be done with the engine cold, especially if a backpressure flushing kit is being used. Completely draining and refilling the cooling system every two years will remove accumulated rust, scale and other deposits. Coolant in late model cars is a 50/50 mixture of ethylene glycol and water for year round use. Use a good quality antifreeze with water pump lubricants, rust inhibito