radiator problems

5 Most Common Radiator Problems and How to Avoid Them

Daniel McDonald
Daniel McDonald8 min read
5 Most Common Radiator Problems and How to Avoid Them

5 Most Common Radiator Problems and How to Avoid Them

Your car consists of many elements that need to work correctly so that the vehicle can take you places. Unfortunately, we usually ignore the radiator problems and other cooling system components unless we notice any visual problems.

However, cooling system inspection is essential for the maintenance of a car. You should not be too worried, though, because radiator problems are common and will not cause further damage if you fix them on time.

The cooling system in your car can be one of the most critical aspects of the longevity of your vehicle. Still, it can also cause significant problems if not maintained well and if you ignore any issues. 

As the centerpiece of the cooling system, the radiator needs to be in good working condition for your car to function properly.

Here are the five most common radiator problems, as well as how to avoid them so you will not have to waste money on expensive repairs or replacements in the future.

What Is The Cooling System, And What Are The Cooling System Parts

The cooling system in your car removes all the hot air from it. A coolant system consists of a radiator, hoses, thermostat, coolant, and water pump. You must first be familiar with the coolant system to understand the most common radiator problems.


The thermostat takes care of the engine temperature. By regulating temperature, the thermostat controls the coolant movement through the engine. It opens and closes.

The thermostat is one of the most common troublemakers regarding engine overheating. This is because it lets the coolant move through the engine. When the thermostat opens, the engines need to be cool, thus allowing coolant in. When the thermostat closes, the motor is working at the average temperature level. It closes because there is no need to exchange heat.

Water Pump

The water pump pressures the coolant to move through the engine. It helps the coolant reach all of the essential car parts. The pump forces the liquid to move through the system.


Coolant is the fluid that helps the engine cool down. Coolant prevents overheating, so the coolant level must not be low. Also, if your car has an old coolant or low-quality coolant, you need to replace it with a new coolant and do a coolant flush. Look in the overflow tank to check the coolant level regularly.


Finally, we come to the star of the show: the radiator. The radiator cools the car's engine and helps it stay intact. It cools down the fluid that cools the motor (the coolant). It releases all the excessive heat from the car, thus preventing overheating.

Radiator Parts

The radiator has a few parts that need to be in excellent condition if you want to avoid some of the most common radiator problems.

Radiator Core

The radiator core consists of housing or cooling fins that release hot air. The heater core is a big metal block where hot coolant lets go of all the heat.

Radiator Hoses

The hoses are the rubbery part where the coolant moves through the engine. They are a common culprit for radiator problems.

Radiator Cap

The radiator cap is a pressure cap that prevents the coolant from boiling. It helps the coolant system stay intact under pressure.

Inlet And Outlet Tanks

The tanks are the head of the radiator. They aid the radiator by moving the coolant from the hot metal components.

How Does a Radiator Work?

A radiator is a car's cooling system that helps regulate the engine's operating temperature. The coolant circulates through the radiator hose to the radiator, where the airflow from the fan cools it.

The coolant returns to the engine block to keep the engine at an average operating temperature. If the thermostat fails, the engine can be overheated and cause the car to overheat too.

To avoid this, it is crucial to have your cooling system inspected regularly and to check your car's temperature gauge frequently. If you notice your car overheating, pull over and turn off the engine immediately. Let your car cool down before adding more coolant or opening the radiator cap. Look for any leaks in the radiator hoses or radiator itself.

What Are Signs of Radiator Problems?

If any of the listed signs below are visible, your radiator with plastic tanks may be having issues: 

  • The coolant temperature gauge on your dash is reading higher than usual. 

  • Your engine is overheating, especially when you are stopped or idling.

  • You see steam rising or smoke coming from under the hood. 

  • There is a coolant leak. 

  • Your radiator cooling system needs more fluid than usual. 

  • There's transmission fluid in your radiator. 

  • Your radiator fan isn't working properly.

  • The head gasket is leaking, causing overheating.

Most Common Radiator Problems

Unfortunately, radiators can suffer from various problems, ranging from leaks to clogs. Here are some of the most common radiator issues that car owners may encounter.

  1. A failed radiator fan can cause your engine to overheat.

  2. A faulty thermostat can cause your motor to overheat.

  3. Radiator leaks can cause car overheating too.

  4. Engine coolant levels that are too low can cause your engine to overheat.

  5. Driving in hot weather can cause your engine to overheat.

Rusty Radiator

A radiator filled with rust is not as easy to notice as a rusty car on the outside. Rusty radiator is a hidden problem. But, it will get your attention anyway if you ignore or neglect it.

Oxidation happens in your car since it mixes air, fluids, metal, and electricity. Rust is bound to happen when these processes take place. Also, rust occurs because the system uses water to work. Moisture in the radiator turns into corrosion. Since most car parts have a metal nature, it is no wonder they will erode or rust.

Letting your radiator stay filled with rust can lead to various leaks and holes. When the voltage moves the coolant, it can create damage that will turn into internal rusting or flaking.

A rusting radiator might happen due to harsh weather climates or road salt. So, you should have your radiator checked regularly.

A rusty radiator can cause overheating, component damage, and slower and reduced function of the coolant system. To avoid this problem do a radiator flush and refill it every 30,000 miles. If you notice your radiator is starting to rust, have it checked out as soon as possible. A leaky or rusted radiator cannot keep the engine cool.

To prevent rust build-ups, use coolant flush or anti-freeze together with distilled water to flush it.

Leaking Coolant

Coolant leak is one of the widespread radiator problems. Coolant leaks might happen for several reasons, such as radiator corrosion or radiator hose corrosion. A leak will lower the coolant level, which must not be too low.

A proper amount of coolant constantly moves from the radiator to the engine, which puts a lot of pressure on the radiator hoses and might eventually end in a leaking coolant. Damaged hoses let the coolant go out of the system, thus causing overheating. If you notice some green thing with a sweet smell under your vehicle, you should know your radiator is leaking. Also, to detect radiator leaking, pay attention to the coolant level. If you notice a low coolant level, this might indicate a leaking problem. A low coolant level is almost always a leak warning.

A leak in your radiator can lead to significant engine damage if not fixed promptly. To avoid this, check your coolant levels regularly and look for leaks. A simple way to do this is to put a piece of cardboard under your car overnight; if there's coolant on the cardboard in the morning, you have a car leak. Fix it as soon as possible.

Blocked Or Damaged Exterior Radiator Fins

A series of metal fins protect the exterior of your radiator. Over time, these fins can become bent or damaged, which can block airflow and cause the radiator heat to go up.

Damaged fins will cause a clogged radiator since they will not let the air reach the coolant in time. Also, they will not allow the coolant to cool down enough.

If there is something stuck in the exterior fins, you could use a garden hose to wash away all of the dirt that might do the blocking.

Rock, gravel, sand, bugs, dirt, etc., can bend these metal pieces in your vehicle and damage them for good. Problems might arise even when you clean your car. A more significant number of damaged fins might lead to overheating.

If you buy a new radiator, always ask a professional to install it in the car. If you install it improperly, you can cause fin damage too.

To avoid this problem, be careful not to hit the radiator with hard objects and regularly inspect the fins for damage.

Clogged Water Pump Or Faulty Thermostat

All radiator parts must be on their best behavior to keep the engine cool. The thermostat and water pump work together to keep the engine cool.

If the vehicle thermostat does not work correctly, the system cannot tell when to let coolant go into the radiator. Also, if the water pump does not operate correctly, it will fail the pressure test since it will not know how much pressure the coolant needs to circulate in the car.

A low flow or clogged water pump can cause your radiator to overheat. The water pump helps the coolant circulate through the engine and the radiator. If the pump is not working correctly, the coolant cannot do its job, and your engine will overheat. To avoid this problem, have your water pump checked regularly and replaced if necessary.

A high heat mark on the dashboard means a rise in engine temperature, which leads to a faulty thermostat.

Gunk, Sludge Build Up, And Other Obstructions

The most common radiator problem is a build-up of gunk and other mineral deposits. Over time, your radiator will start to collect dust, dirt, and other debris.

These mineral deposits can eventually lead to a clog, preventing your radiator from working correctly. In addition, the build-up will obstruct the radiator from flowing the necessary coolant amount to the engine.

The only purpose of the internal deposits called gunk is to clog all things, preventing cold air from flowing and not allowing coolant to move freely. To avoid this problem, be sure to clean your radiator regularly. In addition, you can take a vacuum cleaner with a hose attachment to remove any debris collected on the fins.

Sludge build-up leads to heating failure, so inspecting your coolant system before it causes further damage is the only solution.


Can Transmission Fluid Get Into The Coolant?

Transmission fluid uses a separate passage to move through the radiator and lubricate all the essential parts.

However, sometimes there might be a radiator leak between the passage of the coolant and the one of the transmission fluid.

Also, if there is rapture in the tank, the coolant might mix and contaminate some parts of the transmission fluid.

How Do You Know When It Is Time For A New Radiator?

When the temperature gauge is hot, and the needle is always at the hotter end, when the car is overheating, when you notice some leaking, and when the radiator is rusting, it is time for a new radiator.

Cracks in the hoses, leaking coolant, smudge build-up, and constant overheating are signs that you need a new radiator too.

How Often Should You Professionally Check Your Radiator?

It would be best if you had your radiator serviced every 100,000 miles. Every five years, you should flush the radiator to prevent any damage.

Never forget to open and check the coolant system every 50,000 miles. . Also, check the coolant level every time you fill the overflow tank.

How Much Will You Pay For A Radiator Flush?

A radiator flush will cost about $200. But, of course, the total price will depend on the mechanic, the type of car, and the labor for the job.

Final Thoughts

When it comes to your car, you need to pay attention when it gives you specific signals and never ignore them.

Of course, this applies if you do not want to have any further troubles and costly repairs.

When you notice some of the most common radiator problems, such as leaking coolant, sludge build-up, rusting radiator, bad water pump, or faulty thermostat, address them immediately to prevent engine overheating.

You need to take care of your car and its vital parts if you want it to take you places.