7 Bad Radiator Symptoms (+ Solutions)

Is your car overheating, and you want to know if the problem is from the radiator? Do you want to know the various bad radiator symptoms? If the answer to the above questions is yes, you are in the right place.

A car radiator is one of the most important parts of your vehicle. It has to work properly to manage the temperature of your engine. So it is really important that you take immediate action when you notice that something is wrong with your car’s radiator.

This article explains various bad radiator symptoms, how to fix them, and answers any questions you might have regarding the radiator and its repair.

1. High-Temperature Gauge Readings

Having a high reading on the temperature gauge is one of the most common bad radiator symptoms. The sole purpose of a radiator is to make sure that the engine temperature is maintained within a suitable working temperature.

Therefore, if the engine temperature starts to rise too high, it is a sign that the radiator is malfunctioning.

Check the temperature gauge to see or verify that the temperature is higher than it should be. Modern cars come with a digital monitor that notifies you when the engine temperature is higher than it should be.

Your car has an ideal operating temperature reading of about 195 – 220°F. Although if they fall out of this range, it is not always a sign of a problem because some cars have air conditioning that will help to bring down the temperature.

When you notice that the temperature is constantly becoming higher, it could be a possibility of a clogged radiator.

The internal buildup of unwanted deposits and rust is often the reason. In addition, dirt and debris hinder the circulation of the coolant, thereby reducing or stopping the radiator from functioning.

2. Coolant Leaks

Coolant leaks are another common bad radiator symptom.

When there’s a severe rust buildup, the radiator will get clogged, and there will be tiny holes due to cracks on the cooling fans. You will also notice a droplet of coolant on the floor where you parked the car.

Low-quality coolant is largely responsible for the rust in the radiator. Unfortunately, this low-quality coolant is mostly tap water; tap water facilitates rust. Distilled water is way better and is a suitable coolant.

A radiator flush is one way to eliminate this rust; if it remains that way without a flush, more rust will be formed until the radiator is completely damaged.

When the rust has eaten up enough holes, the coolant will leak out, and with time, you will run out of coolant or have insufficient coolant, which will cause the engine to overheat, damaging some engine parts in the process.

When you begin to notice coolant droplets in your garage or see the sign of low coolant on your dashboard, know it is time to verify the problem and properly fix it.

3. Fluid Discoloration

The coolant color is often bright; it’s either yellow, green, or orange. Sometimes it could be blue, red or pink.

This is because it passes through the coolant flow passage in the engine without obstruction or contamination in the radiator.

The coolant gets contaminated over time through internal deposits. This interior deposit can be dirt, debris, rust, or even sludge; any of these can result in a coolant change of color.

To keep in touch with the condition of the coolant, a regular check of the coolant reservoir will help. Note that when the coolant is contaminated, it becomes very thick and difficult to move along the cooling system.

When this occurs, it can lead to clogging, and with time it will result in engine overheating, thereby reducing the radiator’s efficiency and could damage the engine.

There’s more considerable trouble if your car transmission is leaking and mixed with the coolant fluid. Get your mechanic to examine the situation and fix the problem as soon as possible.

4. Blocked Exterior Radiator Fins

Radiators come with tin fin tubes; these tubs are located at the radiator, and they help ensure that the radiator is producing maximum cooling to the engine.

The coolant flows through these tubes, and the radiator fan blows cold air from outside to circulate inside, which lowers the temperature of the tube and the coolant before the coolant returns to the engine.

When dirt, leaves, bugs, or other materials block the air’s flow, the coolant won’t be able to cool down before moving back into the engine, leading to overheating.

Therefore flushing the radiator is very important in a situation like this; flushing will help remove all the unwanted materials hindering airflow.

7 Bad Radiator Symptoms

5. Bent or Damaged Radiator Fins

Apart from the blockage due to dirt debris and other unwanted materials, the airflow can also stop if your radiator fins are bent or damaged.

This is because the fins are carefully designed and are fragile such that a tiny force from things like small gravel can damage it or bend it.

The force that comes during radiator flushing or installation can also damage these fins. The more the fins are damaged or bent, the more radiator gets clogged, and at some point, the car could overheat, causing damage to the engine.

Be careful during installation and flushing of the radiator to avoid such occurrence. If you don’t know how to do it yourself, get the service of an expert and save yourself the trouble of a bad radiator.

6. Passenger Area Heater Not Working

The interior of a car is designed to get heated up during winter or cold season. Hot coolant passes through the heater core, and hot air is blown in through a blower fan.

When the radiator is clogged or blocked with dirt, this hot air won’t be able to find its way to the heater core, and hot air can’t be blown into the car.

More often than not, a thermostat is the cause of this problem, but it is also possible for a bad radiator to cause such an issue.

7. Cold Lower Radiator Hose

When your radiator is functioning correctly, you will observe that as the coolant moves through the hose of the radiator, the upper house will be hot while the lower one will be warm.

When you notice that the lower radiator is cold even after driving the car for some time, this is a bad radiator symptom.

Also Read: Radiator Repair Options And Which You Should Choose

What Is a Radiator?

Many of us do not know the working principle of our cars, and we don’t care to know or pay attention to our car; we only want it to answer whenever we turn on the ignition.

Maybe we know a few parts, perhaps the engine, fuel tank, and the tires, and that’s all we know. But is that how it should be? Of course not! It is imperative we know some of the core components of our cars, such as the radiator.

When your car engine is working, it generates lots of heat. This heat is not allowed to remain in the engine but should be sent out; else, it can result in engine overheating.

Overheating is avoided by pumping coolant through the engine; this coolant receives the heat and moves out of the engine through the engine block.

This coolant will then transfer this heat into the radiator, where the air will be blown around it to bring down the temperature and exchange the heat with outside air.

By passing through a thin metal fin, the coolant is more easily carried to the outside, where it can interact with the outside air to bring down the temperature.

This is the result of the essential operation of the radiator. Fans are also specially arranged in the radiator to assist the hot fluid out of the car. Radiators are designed differently, but the basic principles remain the same: cool the coolant and the engine.

Also Read: Car Overheating When Idle? (Here Is What to Do)

How Does a Radiator Work?

How Does a Radiator Work

A radiator is an essential part of the cooling system. This cooling system includes a liquid coolant, a fan, hoses, and a thermostat.

The coolant moves to the engine from the radiator hoses absorbs the heat and travels back.

As the coolant travels back to the radiator, heat in the coolant is released to the outside air through thin metal fins. These metal fins are arranged so that the coolant will pass through them.

The vehicle grille allows outside air to move in and assist. When the car is idle, the radiator fan helps blow in cold air from outside and blow out the hot air; this way, the car engine remains at a reasonable working temperature.

As the coolant returns to the radiator, it picks up generated heat again, moves it out through the metal fins, and goes back to the radiator, repeating these processes continuously so that the car engine will operate at the right temperature to prevent overheating of the car.

Parts of a Radiator

1. Radiator Core

The primary component of the radiator is the core, and it happens to be the most significant part of the radiator. It comprises metal fins with large metal blocks; these fins allow the coolant to exchange heat with the surrounding air.

Radiator cores are of different types; they are one-core, two-core, etc.

2. Pressure Cap

Pressure is one component present in the car cooling system. This is because the coolant is at a very high temperature without boiling.

Therefore, it helps to offer the system room to be more efficient. On the pressure cap, there is pressure as high as 20PSI; this pressure cap comes with a spring that allows it to maintain such pressure.

Do not remove the pressure cap while it’s still hot; you may get severe burns and hurt if you do.

3. Outlet and Inlet Tanks

The coolant movement from the hot part of your car engine to the radiator is accomplished through the inlet and outlet tanks.

4. Transmission Coolant

Your transmission coolant is more likely the same as the engine coolant. However, the steel pins are where your transmission fluid travels in the car engine.

These steel pins are surrounded by coolant, and the coolant absorbs the heat from them. The radiator also brings down the temperature of this coolant when the automatic transmission produces high heat.

In some vehicles, a different radiator is used for cooling down transmission fluid when the transmission generates severe heat. However, cars with this unique functionality are rare.

Why Is the Radiator Important?

A car radiator is crucial to the car’s operation since it is used to dissipate the heat generated during operation. If your car radiator is not working, your engine will likely overheat and damage the engine components.

Further, a bad radiator can cause your car to emit black smoke, which is very harmful to the environment.

The radiator’s functionality will drop when it lacks coolant or has expired coolant, causing overheating in the engine. However, this can be resolved by flushing off the old coolant and adding fresh coolant.

Radiator Replacement Cost

The cost of replacing a radiator varies based on the car’s make and model; on average, you will be spending about $200 to $900.

A typical aluminum core radiator with good plastic tanks can go for $100-$600, depending on the car model and make. Costs can also vary depending on if it’s Aftermarket or OEM.

The labor cost for the replacement will be about $100-$300. The job can take about 1hr to 3hrs to complete, though this depends on how accessible the radiator is. You should also factor in the cost of other parts and coolant required, so budget about $20-$100 more.

Other Parts to Check If You Have a Bad Radiator

Checking up on other parts of your vehicle when there’s an issue with your radiator is very important. Such parts are the water pump, thermostat, and heater core.

1. Water pump

The water pump is responsible for moving the coolant into the hoses and passages. When the radiator gets bad due to dirt or debris, it affects the water pump and reduces its function; the water pump will likely fail as the damage worsens.

2. Thermostat

The car thermostat is located at the top of the radiator hose. The thermostat monitors the temperature of your car engine, and it helps to checkmate and assists in the control of the engine.

It can achieve this by allowing the cooling fluid to flow freely when the temperature gets to the desired point.

When the radiator stops functioning, there will be a rise in pressure in the thermostat, causing malfunctioning of the thermostat.

The valve meant to open at a specific high temperature and close at a certain low pressure will suddenly get stuck. If it doesn’t open, then the engine will overheat.

Touch the radiator hoses to confirm that the thermostat is stuck; the upper hose will be hot while the down hose will be cold.

If the valve gets stuck open, you will consume more fuel because the correct temperature won’t be reached.

Always fix the radiator when you notice a problem; if not, you will create more problems in the car engine and cooling system. You will also spend more money when you neglect to fix the radiator at the early stage of the problem.

3. Heater Core

The heater core is like a small radiator version; it has a similar job to the radiator, producing warm air. When the debris affects the radiator, it can affect the heater core, and heat movement will stop.

Also, when the engine starts to overheat, the heater core will get damaged due to high temperature and pressure. You will begin to notice fog on your car window, and also, the leak will remain on your floorboards.

Can You Drive with a Bad Radiator?

Can You Drive with a Bad Radiator

It is a terrible idea to drive with a bad or faulty radiator; a faulty radiator creates overheating, and overheating is dangerous for your car engine; it can cause considerable damage to the engine components.

In addition, this will affect the cost of repair; you will spend way more than you should. When you observe that your car engine is overheating, pull out of the road and allow the car to cool down; get a mechanic to examine the vehicle and possibly fix the problem.

Never try to add water to the radiator no matter what; when you do, you create more problems for the engine. In addition, the engine’s internal components will start to rust and get worn out with time, thereby causing a more significant problem.

Also Read: Temperature Gauge Rising but Car Not Overheating (Causes & Solution)

Radiator Maintenance Tips

Maintenance is one way you can help keep your car healthy, and here are how you can keep your radiator healthy and working efficiently.

  1. After your car has gone 36,000 miles or six years, change the radiator hoses by getting new replacements. These hoses are rubber; they get weak after prolonged use, especially under high-temperature conditions. Try not to exceed 50,000 miles without changing the hoses.
  2. Always pay attention to the coolant level; if you notice that it has gone down, fill it up; if it gets down regularly, something is wrong; there’s probably a leakage, trace the leakage and fix the problem.
  3. After 25,000 miles, flush out the coolant and the radiator; this will help remove all dirt, debris, and other blockages. This will also help the radiator to function optimally and increase its lifespan.

Frequently Asked Questions – Bad Radiator Symptoms

What Happens When the Radiator Goes Bad?

The coolant color will change when your radiator gets bad, turning to a rusty color. If nothing is done, it will develop into sludge and will hinder the flow; this will cause the car to overheat, reducing the engine performance and subsequently shut down the engine.

How Do You Know If You Need a New Radiator?

Leaking coolant has been known as one of the common symptoms of a bad radiator. When you park your car in the garage and notice that coolant is dripping from under the vehicle, you will need to carefully check the source of the leak and fix it as soon as possible. Calling your mechanic to inspect and verify the source of the leak is a better idea.

Will a Car Start with a Bad Radiator?

One of the effects of a bad radiator is overheating of the car. This overheating reduces the engine’s performance and, at some point, will completely shut down the engine, and it won’t start any longer. Therefore when you notice that your car is overheating, pull over and allow it to cool down, then call a mechanic to help fix the problem, which is very much likely a radiator problem.

Is It Worth Replacing Old Radiators?

An old radiator is very likely to have rusted parts; this rust contaminates the flowing coolant and causes debris and sludge buildups; all of these depreciate the radiator’s performance and the engine at large. So when the radiator is old, and these signs are prevalent, it is worth replacing.

Conclusion – Bad Radiator Symptoms

The radiator is an essential part of your car engine, one of the vital components of the cooling system.

It helps maintain the engine’s temperature, ensuring it does not exceed the working temperature. In addition, when the radiator is bad or faulty, it affects the entire performance of your car.

When the coolant color of the radiator changes, this is a bad radiator symptom. Other bad radiator symptoms include a bad head gasket, coolant leakage, and a clogged radiator. Any of these can affect the functionality of the radiator.

There could be blockage at the exterior fins of the radiator, causing the engine to overheat. Your car heater can also be affected by a bad radiator, creating more problems for the engine.

When the radiator gets so bad, the best thing to do is replace it with a new one. The replacement cost could be around $500-$1000 depending on the car’s make and model.

However, you may have to flush the radiator in most cases, and everything will be alright.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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