Water In Radiator Freeze – How To Fix It?

Water in radiator freeze can be a common and concerning issue during cold winter months.

Radiators play a crucial role in cooling your vehicle’s engine. When water within the radiator freezes, it can lead to serious damage and potentially leave you stranded on the road.

This post will provide effective tips to avoid this troublesome situation and take preventive measures.

Why Do Cars Need Water In The Radiator?

water in radiator freeze

Cars need water in the radiator to cool the engine while it runs. The engine produces a lot of heat. Without a cooling system, it would overheat and get seriously damaged.

The radiator is an important part of the car’s cooling system.

Inside the engine, parts like the cylinder heads and engine block create a lot of heat. Water will flow through the engine and absorb the extra heat to prevent overheating.

Then, the water goes through the radiator with thin tubes and cooling fins. When the car moves, air passes through these fins and cools the water, releasing the heat into the air.

This process keeps the engine cool and prevents it from getting too hot.

What Happens If Water In Radiator Freezes?

Water freezing in radiator can cause serious damage to the engine and radiator. Water frozen in radiator will expand and trigger a great force.

In the radiator this can lead to cracks and splits, damaging the radiator itself. Yet, the real danger is when ice forms inside the engine block.

Ice forming inside the engine block can crack the main casting called the block.

This is a catastrophe for the engine, as the cost of replacing the engine can be very high, potentially totaling the entire car.

Some may think that freeze plugs in the engine will prevent damage, but they are not designed to save the engine from freezing.

While the freeze plugs may release some expanding ice to escape the engine core, they cannot entirely prevent the damage caused by freezing water.

What To Do If Water In Radiator Freeze?

what happens if water in radiator freezes

If the water in the radiator freezes, you need to remove the ice from the reservoir and pour the water-antifreeze mixture into it. Finally, turn on the engine and check for any problems.

Step 1: Locate The Radiator Reservoir

Open the car bonnet using the latch behind the dashboard’s lower edge. Look for a latch underneath the front central panel of the bonnet to release it.

Besides, the reservoir cap sits on top of a transparent plastic container with MIN and MAX markings, showing the liquid levels inside.

Unscrew the cap and place it on a safe shelf to avoid accidentally knocking it into the engine.

Step 2: Remove The Ice From The Reservoir

Park Your Car In A Warm Garage

When you discover a frozen radiator or frozen water in engine, it’s essential to move your car from the cold outdoor environment to a warm garage.

Pushing the car into the warm garage will allow the heat from the surroundings to work on the frozen water and gradually melt it.

Parking your car in a garage also prevents the outside cold, which will aggravate the freezing of your radiator.

Blow Hot Air In The Radiator

Next, to deal with frozen water in radiator, you can use a hair dryer or heater fan to blow hot air directly into the radiator.

Hold the hair dryer or fan close to the radiator and aim the heat at it. The strong heat will quickly melt the water or frozen engine coolant.

Be patient and keep doing this for a few minutes until the water becomes liquid again.

This step ensures that the radiator is ice-free, allowing the water to flow smoothly through the system again.

Step 3: Mix The Antifreeze With Water

To mix antifreeze with water, ensure the frozen water has melted into a liquid state. Then, drain the old fluid from the cooling system.

Prepare a mixture containing 50% antifreeze and 50% water, and pour it into the system. It’s best to use pre-mixed coolant to ensure the right ratio.

Remember, preventing freezing in the first place is essential.

Always use the recommended engine coolant, especially during winter, to keep your car’s engine running smoothly and avoid any potential damage from freezing temperatures.

Step 4: Pour The Mixture In The Reservoir

To pour the mixture into the reservoir, use a funnel to avoid spills. It doesn’t matter which you pour first, water or antifreeze, as they will mix when the engine starts.

However, use distilled or bottled water, not tap water, to prevent potential engine damage over time.

Pour equal amounts of water and antifreeze, aiming for the MAX mark on the reservoir. If you pour over the MAX level, your radiator will push the water out.

Tighten the radiator cap securely. Be cautious, as antifreeze is poisonous to animals, so avoid spills on the ground where pets could come into contact with it.

Step 5: Start The Engine And Inspect

Start the car’s engine and let it idle for about 10 minutes. Monitor the temperature gauge during this time.

The gauge should settle at the midpoint on the dial, indicating that the radiator levels are adequate to cool the car’s engine effectively.

If the temperature gauge stays within the normal range, the coolant is doing its job correctly.

How To Prevent My Radiator From Freezing Overnight?

Park the car in a warm garage: Parking your car in a heated garage can help keep the radiator and the coolant from freezing during cold nights.

Use a coolant with proper antifreeze concentration: Ensure that your radiator’s coolant mixture contains the recommended ratio of antifreeze to water (usually 50% antifreeze and 50% water).

This will lower the freezing point of the coolant and prevent it from turning into ice in low temperatures. Remember that bad mixed or insufficient coolant will make the coolant blow out of the reservoir.

Check for leaks: Regularly inspect your radiator for any leaks or cracks that could lead to coolant loss. A well-sealed system will retain the antifreeze and prevent freezing.

Use a radiator cover or insulation: Adding a radiator cover or insulation during extremely cold weather can help retain heat and protect the radiator from freezing.

Avoid using plain water in the radiator: Only use distilled or bottled water when topping up the radiator.

Tap water may contain minerals or impurities that can damage the radiator and reduce its effectiveness.

Can I Drive My Car With a Leaky Radiator? 

No. You shouldn’t drive with a leaky radiator because it can lead to serious problems. When the radiator leaks, coolant is lost, which can cause the engine to overheat.

Overheating can result in severe engine damage and leave you stranded on the road.

If you notice a leaky radiator, it’s best to avoid driving the car if possible.

Instead, have the radiator inspected and repaired by a qualified mechanic as soon as possible to prevent further damage and ensure the safe operation of your vehicle.

At Which Temperature Will Your Radiator Freeze?

car radiator frozen

Your radiator’s coolant will start to freeze when the temperature drops below the freezing point of the mixture used in your car’s cooling system.

The coolant’s freezing point depends on the antifreeze ratio to water.

For example, a 50/50 mixture of antifreeze and water typically freezes around -36°F (-38°C), while a 70/30 mixture freezes at about -84°F (°C).

Using the appropriate coolant mixture is essential to prevent the radiator from freezing in cold temperatures.


Can I Only Use Water Instead Of Antifreeze?

Yes. But it’s best to mix it with coolant.

It is because the coolant contains chemicals that lower the mixture’s freezing point, preventing it from freezing at temperatures below 32 degrees Fahrenheit.

It also raises the boiling point of the coolant, protecting the engine from overheating in hot weather.

Therefore, using antifreeze in the radiator is essential to ensure proper engine cooling, prevent freezing, and protect the engine from potential damage caused by extreme temperatures.

What Should I Do If I Don’t Have Antifreeze In An Emergency?

If you don’t have antifreeze in an emergency, and your engine is overheating or low on coolant, you can use the highest quality water as a temporary solution.

Ensure the engine is off and cool before adding water to the radiator.

Slowly pour water into the radiator until it reaches the fill line. It will help cool down the engine and prevent further damage.

However, replacing the water with the appropriate antifreeze as soon as possible is essential to protect your engine from freezing and prevent corrosion in the cooling system.

How Long Should I Add Coolant To The Radiator Again?

It’s best to add coolant to the radiator again immediately after a technician has checked, repaired and flushed it.

Once the repairs are completed, you should use the coolant to ensure the proper functioning of your vehicle’s cooling system.


In conclusion, understanding the risks of water in radiator freeze is crucial. It can maintain a healthy and functional cooling system in your car.

Using a 50/50 mixture of coolant and water or pre-mixed coolant is best. They can help prevent engine freezing and ensure optimal performance during cold weather.

Regular maintenance and proper coolant levels will help safeguard your car’s engine and radiator, preventing costly repairs and ensuring a smoother driving experience in winter.

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