How To Check the Coolant System on a Used Car

The car's coolant system keeps the car from overheating. If a car regularly overheats, this can lead to more serious problems, like permanent damage to the car's engine or other costly repairs. Keeping the car's coolant levels at recommended levels keeps the car on the road longer and prevents serious damage.

• Most modern cars have a coolant reservoir tank, which is a plastic tank attached to the coolant system. It has two levels-one for when the car is hot and one for when it is cold. If the fluid in the reservoir reads beneath the appropriate level, add antifreeze to the reservoir by removing the reservoir cap and pouring the antifreeze or water if you have no antifreeze handy, directly into the reservoir.


• In some used cars, particularly older ones, there will not be a reservoir and you will have to check the radiator directly. This can be more tricky and dangerous. Never open a radiator cap when the car is overheating. Steam and fluid can shoot out of the radiator and cause serious injury.


• After you have given the car time to cool, slowly turn the radiator cap. Do so by putting a rag around the radiator cap, again to prevent any injury. If steam or fluid starts to come out, tighten the cap again and do not try again until you have given the car additional time to cool off.


• If no steam comes out of the radiator, slowly turn the cap until it has been removed. Once the radiator cap has been removed, check the coolant level in the radiator. If the coolant is low, add the proper amount of antifreeze, only adding enough to fill the radiator. Do not overflow the radiator.