What exactly does a radiator and antifreeze do?



So I drive a pretty old SUV and it’s had a radiator leak for awhile. I can deduce that anytime I start to run low on antifreeze it begins to overheat. But I don’t exactly understand the causation behind it. Clearly, no antifreeze—overheat. But how exactly does that happen?

Ps. I am not mechanically inclined. I never had anyone teach me about any of this so I’m learning on my own. My mechanics are really helpful! But I don’t want to bother them as they’re super busy. Thank you all!

In: Engineering

Your engine has a cooling system. It circulates coolant (water or antifreeze) around the engine to prevent overheating. The radiator is the part that takes hot coolant from the engine, and cools it down so it can be sent back to move more heat.

When the coolant leaks out the system starts to run low, which means it can’t cool down the engine so the engine overheats.

The engine is very hot unless something is present to take away the heat. The radiator fluid, made up of antifreeze and water, is heated up by the engine and then is cooled by air in the radiator, allowing the engine to be cooled

Antifreeze has become a catchall term for what you put in your radiator, but antifreeze is really an additive that you mix with water, which you then put in your radiator.

Your radiator takes heat away from your engine to prevent it from overheating and seizing up. If the metal gets too hot it expands and grinds more, putting more wear on the engine until it eventually just stops working altogether and the engine seizes, at which point you probably need a new engine.

Water alone is a good way to carry the heat from the engine to the grill, where the heat can transfer to the air flowing through the front of your car.

Antifreeze was originally a mixture designed to do exactly what it says on the tin: prevent the water in your radiator from freezing in cold weather. A frozen radiator is pretty obviously not good for your engine. Parts will overheat before the water can fully thaw, and the ice can clog and damage parts of the system.

Modern antifreeze is a more complex mix that makes the water do its job better in addition to preventing it from freezing. It helps lubricate the water pump and raise the boiling point so the water doesn’t boil either. You *can* run your engine with just water, but it will run much better with an antifreeze mixture.

You will usually see some antifreeze bottles labeled as “50/50” which is a mix of 50% antifreeze chemicals and 50% water, which is the mixture you want. Other bottles are 100% antifreeze chemicals and need to be mixed with enough water to make that 50%/50% mix.

There are also different kinds of antifreeze that come in different colors, which shouldn’t be mixed, but they accomplish roughly the same thing.

When you have a hot cup of coffee, most people blow on it to cool it down. The heat of the coffee is going to the air you’re blowing on it. In the case of the car engine, there’s a middleman (coolant) to reach all the nooks and crannies of the engine. The heat is picked up by the coolant and dropped off at the air flowing into the radiator.

If there are no visible puddle. Check that fluid is not leaking into the engine. When was the last time you changed your oil? Is the oil thick or is it watery? Is your engine producing excessive white smoke indicating water is going out the exhaust? A new radiator will not fix these issues if they exist.