How to Stop a Radiator Leak in a Car

How to Stop a Radiator Leak in a Car

How to stop a radiator leak in a car depends on the cause. Of course, you may see water or coolant levels drop and rush to find a solution, but there could be more than meets the eye.

Steam or hissing sounds are also significant radiator leak symptoms.

A rule of thumb is you check your car’s cooling components regularly. A routine assessment of the radiator and engine parts will help you notice leakages before finding a solution.

For example, rust is a top sign of a leaking radiator, resulting in damages and unnecessary costs if overlooked for long.

The most prudent way to avert losses is to fix leakages based on the causes and signs. Read on to find out how you can go about troubleshooting and stopping a radiator leak in a car.  

How to Stop a Radiator Leak in a Car

1. Fluid ooze under the car

If a patch of fluid leaks under the car, there could be an engine or cooling system problem. But before you jump to conclusions, confirm the leakage cause since it can also be from the steering oil.

A smart approach to affirm the cause of leakage is to analyze the oozing fluid and the entire cooling system. You can even smell the leaks, to be sure. If it is water, you will see a clear, odorless stain.

A coolant’s leak color will vary: green or orange, with a nasty or slightly sweet smell. Don’t confuse this with engine oil—it is always darker and greasy, depending on how long it has been in use.

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2. Hissing sound 

Whenever the radiator hisses, it is a sign of a malfunction in the cooling system components. The leak can result from the radiator not working well.

Also, maybe the cap is loose or stuck, allowing pressure to escape unnecessarily.

A radiator cap should allow a small amount of air out to maintain pressure levels in the cooling system.

If it is loose, it lets excess air move out, hence the hissing sound. It can also build up pressure in the cooling system if it jams, leading to leaks or cracks on the radiator hoses.

Your best shot to ensure the cap functions to perfection is you replace it.

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3. Engine overheats

A radiator regulates heat from engine combustion. If the cooling system fails, the engine overheats. This causes steam to appear from the hood, and the dashboard engine light blinks.

Sometimes, the car will run hot, but the radiator stays cool. This is a sign the radiator is functional. So, what could be the problem?

Well, a thermostat valve that cannot control coolant flow through the engine is your culprit.

Your first move to stop the leak is to locate the radiator hose connecting to the thermostat and pull it off. Remove the bolts and the gasket.

Clean any substance that could be stuck in the hole and fit in a new thermostat. Lastly, replace the radiator hose, fasten it carefully, and replace the lost fluid.  

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4. Radiator rusts

Rust results from the oxidation of metals and can cause significant corrosion to the radiator. An easy way to check if the radiator is rusty is to clean it first.

Ensure you pay attention to the undersides as they are the most vulnerable to form rust when leakages occur. If you see any brownish or reddish coat concentrated in any part, chances are that it is rust.

How you fix it depends on the size of the eroded part. You should replace the whole affected part if the leakage is huge, but if it is small, you can patch it with a bonding filler putty.

You can also paint the patch to avoid future rust. 

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5. Coolant level drops

The coolant level should be constant for cars with a sealed cooling system, but leaks can cause it to reduce.

An easy tact to note the drop is to assess the radiator water tank gauge while the engine is off and cool.

You can also check the coolant level in the radiator by pressing and twisting the cap to open.

If the coolant isn’t near the top of the reservoir, there could be a leak from the radiator, gasket, or hoses.

You can use a coolant leak repair sealant to fill the leakages. Alternatively, get a mechanic to pressure-check the entire cooling system and fix the damaged part.

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6. Road impact

Road impacts like hitting potholes, bumps, or collisions can cause leaks on the radiator. The damage can also spread problems to the water pump, which supplies water to the cooling system.

In such instances, the only best solution is to replace the radiator or water pump. Opting to repair either of them will be unviable since it is often hard to tell the damaged part. 

7. Cold weather

Icy weather causes water and coolant fluid in the cooling system to freeze. This can crack the radiator or burst the hoses.

If you drive under cold conditions, it is wise you mix a 50:50 ratio of antifreeze fluid with coolant to prevent radiator water from freezing. Be sure to top the mixture since it degrades and boils off.

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Frequently Asked Questions on Stopping Radiator Leakages

1. Why should you flush the radiator in a car?

The radiator often picks debris and contaminants that can clog the cooling system. Flushing ensures it stays clean and serves you longer.

2. How do you assess the coolant level if there are no leakage signs?

You can mark the reservoir with a pen before driving off and check it later after returning or reaching your destination.

3. How often should you inspect the radiator?

There is no set period for inspecting the radiator unless you suspect a leak. But again, you should always assess the cooling system for signs of rust or a loose hose.

4. Can a fault in the head gasket lead to coolant leakage?

A faulty head gasket can cause engine oil, coolant, and fuel to leak into the cylinder. An effective way to note the exact leaked fluid is to check the color or smell.

Now that you know how to stop a radiator leak in a car, ensure the engine is off before you work.

Otherwise, you risk overheating it and causing further damages. For a full radiator replacement, it is wise you take your car to a qualified mechanic as soon as possible.

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