A car’s cooling system can be among the most neglected components when it comes to service. Delaying or omitting regular service on a car’s cooling system will usually reward you with an unscheduled stop on a steep grade. Or, it can simply dump all the cooling system’s contents on your driveway, which is not good for the car, the driveway, or you.
This is a problem that requires at least some form of repair. If left alone, it may cause a blown head gasket or a cracked engine block, all of which will cost considerably more than this routine cooling system service.
So, let’s start with the basics. Your cooling system circulates coolant (not just water, but more on that later) through your engine to control its temperature. Engine combustion of fuel (gasoline or diesel) creates heat, and the cooling system provides a counteraction to that heating.
Coolant flows throughout the engine, and the radiator cools it. In the interim, coolant flows through radiator hoses, the heater core, and the water pump. If any of those elements becomes clogged or fails, or you run low on coolant, you have the potential for an overheating engine.
The simplest way to avoid overheating is to service the system every two years or according to your car manual recommendations. Flushing the coolant and replacing it with fresh fluid every two years or 30,000 miles is a good rule. While you perform this service, inspect the hoses and radiator cap for wear. If the hoses are soft to the touch, show signs of wear, or are over five years old, replace them. That not only includes the large top and bottom radiator hoses but also any heater hoses that connect to the heater core.
The radiator cap can lead to overheating all on its own. Through pressurization, the cap allows the coolant to operate at temperatures that would normally cause it to boil over. This is why your radiator can operate at 240 degrees Fahrenheit rather than fail at water’s usual boiling point of 212 degrees. Visually inspect the cap to make sure the spring is not rusty and that the rubber gasket that contacts the radiator inlet is not dried out or damaged.
Coolant and antifreeze are generally interchangeable terms since both come in the same bottle. If you buy coolant it has antifreeze properties — and vice versa. Coolant keeps your engine from overheating. Antifreeze keeps your cooling system from freezing when the engine is off. For purposes of this discussion, it’s all coolant.
If you live in extremely cold climates, you may need to adjust the percent of coolant/antifreeze to water. You might also invest in an engine block heater. Ask your local mechanic or dealership technician for specifics relative to your location.
Many years ago, radiator systems chiefly used water alone to cool the engine. Today, a 50/50 mix of coolant and water will deliver the best protection. Coolant manufacturers have bottled their products in two ways: 100% coolant you have to mix with water and already mixed half-coolant, half-water solutions.
TIP: Be careful not to purchase the 50/50 mix solution and then add water to your system, or you will dilute its effectiveness.
Coolant is chiefly made up of ethylene glycol. Most vehicles, direct from the dealership, come with green coolant except for Toyota, which uses a red fluid.
Aftermarket coolant is generally green or orange but can come in other colors like blue, yellow, purple, or pink. If your vehicle uses an orange coolant, it’s intended for extended-term use and contains additional rust inhibitors. It is not interchangeable with standard green coolant.
Always keep your system filled to the appropriate indicated line on the cooling system reservoir. Most reservoirs have two fill lines noted on the side; one for when the engine is cold (the lower line on the reservoir) and the other for when it is at operating temperature. Overfilling the system is wasteful since excess coolant will bleed off through the overflow outlet.
Never take the radiator cap off unless the engine is completely cool, or hot coolant will erupt under pressure. Always fill the cooling system through the reservoir. When the engine warms up, it will draw the fluid into the radiator. After a day of driving, recheck the reservoir level and top off as needed.
In the past, do-it-yourselfers would flush their cooling system in their driveways. Several companies today still offer aftermarket flush and fill kits. The kit allows you to insert a “T” fitting into the heater hose and connect a garden hose for clean water. After draining out the coolant by opening the petcock at the base of the radiator, the garden hose would force cool water through the engine, water pump, hoses, and radiator to remove scale and debris.
However, we do not recommend this procedure anymore because changing your coolant at home is extremely toxic to humans and pets. Also, proper disposal is important because emptying the fluid in your garage or driveway could allow it to end up in the water system.
For this reason, we recommend getting a coolant flush performed by a professional shop. If you refill your coolant at home, make sure to clean up all spills and drips as ingesting even a small amount can cause illness.
