How To Know You Need a New Radiator? (5 Easy Signs) 2024

Finding yourself on the highway with an overheating engine can leave you confused. You assess the emitting smoke, wishing you knew how to tell if you need a new radiator. A functioning radiator will reduce the possibility of this situation occurring.

Your engine is overheating because the temperature is extremely high. The heat generated when power is produced can damage the engine by melting plastic parts and cracking the metals. The radiator was designed to manage this heat by cooling the engine.

Reading this article will help you decide when to replace your radiator and save you from a reoccurrence. Knowing how to identify a bad radiator is the first step to consider.

How do I Know When my Radiator is Bad or Need to Change it?

Here are the signs when you need a new radiator:-

  • The engine is overheating.
  • Low coolant due to leaks
  • Coolant fluid discoloration
  • Failed Passenger’s heater
  • Radiator’s fins are damaged or blocked.
How do I know when my radiator is bad?

Those as mentioned above are common symptoms you should take note of. You can find a detailed explanation in our section about signs that you need a new radiator to learn more. The next step is to know when your radiator is ready to be changed.

When should the radiator be replaced?

It is not wise to overlook a faulty radiator, specifically if other problems arise concurrently beyond your control. In addition, the issue beginning with your radiator can eventually affect other systems in your vehicle. Therefore, you should consider getting a new radiator to save your car and avoid costly repairs.

Signs you need a new radiator.

A bad radiator would fail to regulate the temperature of your car’s engine, consequently subjecting the vehicle to more damage. Having understood your radiator’s critical role, you must know how to tell if you need a new radiator. These are the signs you may notice.

The engine is overheating.

Your engine requires a functioning radiator to remain cool. Overheating occurs when the temperature becomes too high while driving. At this point, you would notice the constant high reading of your temperature gauge as the needle of your gauge rests in the red region.

Subsequently, your overheating engine could shut off suddenly. Also, you may see steam blowing from under the bonnet of your car. All these occur because the cooling ability of your radiator has declined, and the coolant cannot get to its proposed destination. 

Low coolant due to leaks

Your radiator’s function is to eliminate heat from the liquid coolant and send it back to the engine. The coolant can begin to leak through a failed or cracked radiator during its flow. You may never notice the leak until you see a green, red, or yellow liquid pool underneath your car.

The coolant level decreases faster than usual, causing your vehicle to operate with an inadequate amount. In addition, the plastic component of your radiator can become brittle and eventually crack, causing visible leaks.

Coolant fluid discoloration

The coolant should be in a liquid state, brightly colored, and with viscosity as water. The wearing down of your coolant increases the chances of corrosion inside your radiator, which is not visible. In addition, a rusty radiator contaminates the coolant fluid, making it rust or oil-tinted.

Alternatively, flaking can start in the coolant allowing a sludge that cannot cool the engine to sufficiently form. The contaminated coolant is thicker and causes clogging in the radiator. You will only notice this if you look into the coolant overflow tank. At this point, a flush of the cooling system is needed to prevent more damage to your vehicle.

Failed Passenger’s heater

If your heater is not working correctly, your radiator must have gone bad. Your car’s cabin heater relies on the heated coolant flowing through the heated core. Therefore, enabling hot air to be blown into the Passenger’s area by a blower fan.

Insufficient coolant reaching the heater core will not allow the car’s interior to be adequately warmed. As a result, you may not get the level of heat you desire on a very cold day. Although a bad thermostat can cause this issue, a bad radiator might be the perpetrator in other cases.

Radiator’s fins are damaged or blocked.

For your radiator to do its cooling job, it requires maximum airflow. Thin tubes looking like fins in front transmit the coolant away from the engine. As you drive, the temperature of the coolant is reduced by air passing over the fins.

Radiator's fins in good condition

When these fins are blocked, airflow cannot happen maximally. This prevents the decrease in the temperature of the coolant. The clogging of the thin tubes can be due to leaves, bugs, or debris gaining access to them. Enough room is usually created in the vehicle to allow you to spray the radiator with a garden hose.

In addition to blockage, your radiator fins might be bent or damaged. These delicate fins could be affected during installation or spraying water at a high pressure to clean them. Using concentrated steam or pressure washer can curve the fins, blocking the free flow of air.

A damaged component in the cooling system can affect other parts. Similarly, your radiator functions together with other necessary components. Therefore, you should consider replacing other affected parts when installing a new radiator.

When replacing a radiator, what else should be replaced?

Your radiator’s inability to cool is not the only problem you should be concerned about. Three significant components keep your cooling system running; these are likely to fail when your radiator is bad. Keep your thermostat, water pump, and heater core in mind when checking out a new radiator.

The thermostat is found at the end of the top radiator hose. It reserves the coolant until it is needed to cool the radiator. Unfortunately, a bad radiator applies much pressure on the thermostat, causing it to fail. In addition, the thermostat valve, which can be opened or closed, will get stuck and lead to your engine overheating.

Your water pump moves coolant through the cooling system’s hoses, using an impeller made of plastic. This will also be affected by debris breaking away from the radiator. Pieces of the impeller falling off due to damage will undeniably disrupt the speed of the coolant flow.

Lastly, the heater core has a network of gauge tubing, working to produce hot air for the heating system. However, excess pressure and temperature from an overheating engine will break the connections on the heater core. Replacing the heater core and a damaged, or cracked radiator will resolve this. 

What causes a cracked radiator?

Cracks in a radiator could be due to thermal stress incurred on the metal and plastic in the radiator, as it operates between ambient temperature and very high ones. It can also be poked by rocks that may find their way into the grill. The small holes are created to result in drips under the vehicle.

Other initiators of cracks in the radiator could be either accident impacts at the front of your vehicle (where your radiator is located) or contact with a wobbling radiator fan due to bad bearing. In addition, corrosion caused by the dirty coolant in the radiator and high pressure from expanding fluids could also lead to cracks.

How long does it take to change a radiator?

If you consider changing your cracked radiator, you should set aside 2 to 3 hours for the job to be done. The time taken will depend on the person’s skills working on it. Other services involved in the process could prolong the time by 30 minutes.

During the first time fixing the issue, locating elements and other parts can eventually extend the duration beyond 7 hours. After carrying it out a couple of times, it will become easier and faster. Learn about the cost of changing your radiator in the point below.

How much does it cost to replace your radiator?

The radiator is not repairable but can be replaced when there is structural damage in the radiator. When considering a substitute, you can involve your mechanic to get a precise estimated cost. The cost of replacing your radiator varies with the model of the car.

You should spend between $500 and $800, incurred labor costs. Changing it yourself as a DIY car owner can save you money by buying an aftermarket radiator of $100 to $200. The new coolant will round it up to $250.


Should the radiator be filled to the top?

You can fill the radiator up to the specified liquid level marked but do not overfill it.

Will a car start with a bad radiator?

Yes, it will; you are safe if the engine is not overheating. Please do not run the car until it becomes too hot. Instead, use the extra time to get your replacement done.

How long should radiators last?

Radiators that are appropriately maintained should last for 8 to 10 years, with a minimum of 3 years.

Wrapping Up

In conclusion, you now know how to tell if you need a new radiator. You should constantly keep an eye on it to guarantee your safety and that of your vehicle. If you have decided to replace your radiator, check out what else can be replaced to keep your car in good working condition.

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