Water in Radiator – Can you put water in the radiator?


Your car’s radiator is one of the most important components of your car. The normal internal combustion engine produces a lot of heat which when not controlled can cause serious damage to your engine internal components. The radiator plays the important role of heat dissipation.

When your radiator fails, your engine starts overheating. You will notice that the temperature dials on your dashboard rise up. If you do not stop the car at this moment it will shut off itself further causing more damage.

How the radiator works

Part of the radiator system is a thermostat that constantly checks the coolant temperature. The combustion process is intensive, coupled with the constant friction of metallic elements a lot of heat is generated.

The thermostat will be constantly monitoring the internal temperature of the engine and the moment it notices a peak it allows the flow of water and the coolant to the engine parts. The coolant will pick the heat from the engine hence cooling it. This hot coolant is passed to the radiator where it is later cooled.

The radiator has some air vents which cools the hot coolant as it passes by. This process of cooling the hot the engine is constant but there moments the process fails.

Firstly, if your thermostat fails then it will not release the coolant at the right time hence leading to the engine overheating. There also cases when the coolant system develops leaks or becomes clogged hence preventing the efficient flow of coolant along the engine system.

Benefits of using a coolant for your car

The coolant is an essential component for efficient engine performance. At its basic level, most coolants are made from a mixture of ethylene glycol and distilled water. You will also have motorists referring it as an anti-freeze agent.

The color varies depending on manufacturer with most of the coolants being either green or orange in color. You will find the coolant container near the radiator block. The coolant container has minimum and maximum levels.

The radiator has grills at the front that are used for heat dissipation, it also works together with the car fan. When you start driving the internal combustion starts generating heat in the engine.

The coolant and distilled water circulate through the engine block hence helping in heat dissipation. This hot coolant is then passed to the radiator where the air vents cool it and it is re-circulated to the engine block again.

Heat absorption

The first task of the coolant is heat dissipation. Since it has a high boiling point, it works better in heat dissipation than normal water. The internal combustion engine ignition of the air/fuel produces a lot of heat.

This heat when not transferred from the engine block can cause further problems. The thermostat is the one responsible for heat regulation in the radiator.

Freeze protection

Coolant is used instead of water because it has a low freezing point. This comes in handy for people who live in places with extreme winter temperatures. Water would solidify making it useless in engine heat dissipation.

This would cause further damage to your engine block as water turns into ice. Solidified water puts more pressure on your engine block as it expands. The coolant does not suffer from this problem and maintains its viscosity no matter the engine temperature.

Prevent engine rust

Water can cause corrosion on the various metallic components in your engine. But, the coolant won’t hence its preference to water for engine heat dissipation. You should change your coolant regularly as it succumbs to electrolysis and becomes acidic.

When this happens the acidity starts interacting with your engine metallic parts causing further problems. You should check the coolant container to know how frequent you should change your coolant. Most motorists flush out the coolant after every 50,000 miles. Also, know that the coolant is extremely poisonous and should not be swallowed.

Signs that your radiator is failing

The radiator is an important component for efficient engine performance. It helps in heat dissipation. But, how does one tell that the radiator has stopped working or the coolant is leaking.

Engine overheating

Under normal conditions your engine cooling system will keep your engine cool but when it fails it your engine overheats. This is a clear sign that your radiator is failing.

This is often accompanied with the engine temperature gauges on the dashboard going up. Sometimes the solution can be as simple as refilling your coolant but if the gauge continues going up it means that the radiator is not cooling your engine.

The normal operating temperature for the engine is usually 195 to 220 degrees. Anything higher than this is a symptom of engine trouble. However, do not worry so much if it rises during extreme hot summers.

Low coolant levels

Once you notice that the temperature gauge keeps rising the next step is to check your coolant levels. There is an indication of maximum and minimum levels. If you notice that every time you add the coolant it keeps going to minimum levels then you could be experiencing a leak. You can check underneath your car engine for signs of leaks. A leaking coolant is identified by its bright color mostly a green or orange color.

Sludge buildup in the radiator

The radiator system is run through a serious of pipes that help in pushing hot coolant from the engine to the cooler radiator parts. When these pipes become clogged then the safe passage of the coolant is hindered.

One of the reasons for a clogged radiator system is when you use a cheap coolant. The radiator fins are metallic in nature and with time they develop rust. This rust coupled up with a cheap coolant leads to clogging of your radiator. Rust will also develop when you use normal tap water instead of distilled water for your radiator.

When you have a clogged radiator system the only solution is to flush out the cheap coolant and normal water. This will take care of the impurities in the system.

Contaminated coolant

Most coolants have a bright green or yellow color. It also has a high viscosity and flows freely through the radiator system. However, the engine has many deposits, which contaminate the coolant. This makes it less fluid and changes its color to a darker one.

If you do not replace the coolant at this point it will clog up your radiator system hence leading to the engine overheating. The radiator fins are small and subject to more frequent clogging.

Since the fins are the ones that bring in cool air to the radiator they are subject to contamination by dirt, leaves and other airborne materials. To clean the fins you may need to dismantle the radiator system and clean it with a spray nozzle. Other times the radiator fins are bent and in need of re-alignment.


The radiator is one of the most vital components in cooling your engine. The enormous amounts of heat generated through the internal combustion process is very high and if the engine is not cooled in time it will lead to further damage to the engine components. Coolant is used instead of water in the radiator due to its high boiling point and low freezing point. You identify the coolant by its bright green or orange color.

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Steven Reilly
Steven Reilly is a qualified mechanic and his passion for cars goes beyond just the technical aspects. He is also an amateur racer and all round car enthusiast. When he is not driving them, he can often be found in his garage under the hood of a rare model. Steven Reilly has lost track of the number of hours he has spent setting up his fine collection of rebuilt models. He believes that cars can provide a constructive and fun opportunity to teach the youth important life skills. In line with this, he is developing a community outreach program, potentially dubbed ‘Cars for change'.


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