Clogged Radiator or Blown Head Gasket? (How to Tell)

✔ This article has been fact checked.

When your car is experiencing problems with overheating or poor engine performance, it can be difficult to determine whether the issue is related to a clogged radiator or a blown head gasket.

Both problems can have similar symptoms and can be caused by a variety of factors, including neglecting regular maintenance, poor quality coolant, or driving conditions that put extra stress on the engine.

One way to know the difference between a clogged radiator or blown head gasket is to check the engine oil filler cap, if it's milky and frothy it's likely to be a blown head gasket.

In this article, we will discuss the signs of a clogged radiator and blown head gasket, as well as how to diagnose and fix each problem.

Table of Contents:

• Clogged Radiator Signs

• Blown Head Gasket Signs

• Which One Is It?

• Similar Issues

• Driving With a Clogged Radiator

• Driving With a Blown Head Gasket

• Fixing a Clogged Radiator

• Checking for a Blown Head Gasket

• Using a Combustion Leak Tester

• Cost to Replace Head Gasket

• Conclusion

Signs of a Clogged Radiator

Below are some of the common symptoms of a clogged radiator.

1. Overheating

2. Coolant leaking

3. Radiator damage

4. Discoloured coolant

1. Engine overheating or a high coolant temperature

One of the most obvious signs of a clogged radiator is a high coolant temperature or engine overheating. This can be caused by a buildup of debris or corrosion inside the radiator, preventing proper heat dissipation and coolant flow.

2. Coolant leaking

Another sign of a clogged radiator is coolant leaking from the system. This can be caused by a crack or hole in the radiator or damage to the hoses or fittings, sometimes the higher pressure caused by the radiator blockage can cause coolant leaks.

3. Visible damage to the radiator

Inspect the radiator for visible damage such as bent fins or corrosion, this could be indication that the radiator is clogged.

4. Discoloured coolant

If you notice that the coolant in your car is discoloured, it could be an indication that the radiator is clogged. Coolant should be a clear or yellowish colour (sometimes pre-mixed coolant is blue or other coolers).

If it appears brown or rusty, it may contain debris or rust that has built up inside the radiator.

Signs of a Blown Head Gasket

Below are some common symptoms of a blown head gasket.

1. Overheating

2. Milky looking engine oil

3. White exhaust smoke

4. Reduced performance

5. Rough idle

1. Overheating engine

An overheating engine can be caused by a blown head gasket, as the gasket is responsible for separating the engine block and cylinder head and maintaining pressure between them.

If the gasket is damaged, coolant may start leaking into the engine and reducing the amount of coolant available to regulate the engine temperature. As a result, the engine may overheat, which can cause severe damage to internal components if not addressed promptly.

2. Milky looking engine oil

A blown head gasket can also cause contamination of the engine oil, leading to a milky or frothy appearance in the oil filler cap. This is because coolant is leaking into the engine oil and mixing with it, which dilutes the oil and affects its lubricating properties.

This contamination can cause damage to the engine bearings, cylinder walls, and other critical components.

An example of what coolant in the oil filler cap looks like.

3. White smoke from exhaust

White smoke coming from the exhaust tip is another clear indicator of a blown head gasket. This smoke is caused by coolant that has leaked into the combustion chamber and is being burned along with the fuel.

The white color of the smoke is due to the high water content in the coolant.

> Read more about the causes of white exhaust smoke

4. Poor engine performance

A damaged head gasket can also lead to poor engine performance, as the engine may not be able to build up enough compression or may be losing power due to coolant leaks.

The loss of compression can reduce the engine's efficiency and overall power output, leading to decreased acceleration, sluggishness, and a decrease in fuel economy.

5. Rough idle

A rough idle can be a sign of a blown head gasket, as the compression in the engine may not be consistent across the cylinder. This can cause an imbalance in the engine's combustion process, leading to a rough and unstable idle.

In severe cases, the engine may stall or misfire, which can further degrade the performance and potentially cause damage to internal components.

Clogged Radiator or Blown Head Gasket?

If you're experiencing one or more of the symptoms listed above, it can be difficult to determine whether the issue is related to a clogged radiator or a blown head gasket.

One way to know for sure is to check the engine oil filler cap. If it's milky and frothy, it's likely to be a blown head gasket. However, it is important to seek professional help for proper diagnosis.

What Can Be Mistaken for a Blown Head Gasket?

There are several other problems that can be mistaken for a blown head gasket, including the folowing.

• Cracked cylinder head

• Cracked engine block

• Leaking intake manifold gasket

These problems can also cause similar symptoms, such as coolant leaks, poor engine performance, and overheating.

Can You Drive With a Clogged Radiator?

It is not recommended to drive a car with a clogged radiator. Clogged radiators can cause engine overheating, which can lead to serious damage to the engine and other components. It can also lead to a complete breakdown of the car, putting yourself and other drivers at risk.

If you suspect your radiator is clogged, it's best to have it checked and fixed as soon as possible.

Can You Drive With a Blown Head Gasket?

Driving a car with a blown head gasket is not recommended, as it can cause serious damage to the engine and other components. It can also lead to a complete breakdown of the car, putting yourself and other drivers at risk.

If you suspect you have a blown head gasket, it's best to have it checked and fixed as soon as possible.

How to Fix a Clogged Radiator

Fixing a clogged radiator typically involves using a coolant system cleaner and distilled water. Here's a step-by-step guide on how to fix a clogged radiator.

1. Obtain coolant system cleaner and distilled water: Before you begin the process of cleaning your clogged radiator, you will need to obtain a coolant system cleaner and distilled water. The coolant system cleaner is a specialized product that is designed to remove debris and buildup from the inside of the radiator. Distilled water, on the other hand, is used to flush out the cleaning solution and any remaining debris.

2. Mix distilled water with the recommended amount of coolant system cleaner: Once you have the coolant system cleaner and distilled water, you will need to mix them together in the correct ratio. The recommended amount of cleaner will vary depending on the product you are using, so be sure to follow the instructions on the packaging. Typically, the ratio is around 1:1 or 2:1 for coolant system cleaner to distilled water.

3. Drain the radiator using the drain valve: Before you can add the cleaning solution to the radiator, you will need to drain the coolant from the system. The radiator will have a drain valve located at the bottom of the unit. Open the drain valve using a wrench or screwdriver (or whichever tool is required) and allow the coolant to drain completely out of the radiator.

4. Fill up the radiator with the mixture of coolant system cleaner: Once the radiator is drained, close the drain valve and fill it with the mixture of coolant system cleaner and distilled water. You will want to pour the solution in to the recommended level.

5. Allow the solution to sit for 5-10 minutes: After the radiator is filled up with the cleaning solution, allow it to sit for 5-10 minutes. This will allow the cleaner to start breaking down any debris or buildup inside the radiator.

6. Run the engine for 5-10 minutes to circulate the mixture: After allowing the solution to sit, start the engine and let it run for 5-10 minutes. This will help to circulate the cleaning solution through the entire cooling system, ensuring that all areas of the radiator are cleaned.

7. Drain the radiator cleaning mixture: After the engine has been running for 5-10 minutes, turn it off and allow the mixture to cool down. Once cooled, use the drain valve to drain the cleaning solution from the radiator.

8. Add distilled water to the radiator: Once the cleaning solution is drained, close the drain valve and fill the radiator with distilled water. This will help to flush out any remaining debris or cleaning solution from the system.

9. Run the engine for 5 minutes to remove all coolant system cleaner and flush the cooling system: With the distilled water in the radiator, start the engine and let it run for 5 minutes. This will help to circulate the distilled water through the system and remove any remaining cleaner or debris.

10. Drain the distilled water: After running the engine for 5 minutes, turn it off and allow the distilled water to cool down. Once cooled, use the drain valve to drain the distilled water from the radiator.

11. Refill the radiator using coolant and ensure it's up to the right level: Once the radiator is drained, you can refill it with coolant. Make sure to check the level of the coolant, and fill it up to the correct level. This is typically marked on the outside of the radiator. And then check for any leaks and make sure the system is properly pressurized.

Check Prices of Coolant System Cleaner

How to Check for a Blown Head Gasket

Below are some of the ways to check for a blown head gasket.

• Check for a milky or frothy substance in the engine oil filler cap: One of the most telling signs of a blown head gasket is a milky or frothy substance in the engine oil filler cap. This can indicate that coolant is leaking into the engine oil, contaminating it. To check for this, remove the oil filler cap and inspect the oil inside. If you notice a milky or frothy substance, it's likely that you have a blown head gasket.

• Check for coolant in the spark plugs: Another way to check for a blown head gasket is to inspect the spark plugs. If coolant is leaking into the combustion chamber, it may be present on the spark plugs. To check for this, remove the spark plugs and inspect them for coolant or any other abnormal substances.

• Check for exhaust gases in the coolant: Another indication of a blown head gasket is the presence of exhaust gases in the coolant. If coolant is leaking into the combustion chamber, exhaust gases may be entering the coolant system. To check for this, use a combustion leak tester.

• Check the compression using a compression tester: A common method to check for a blown head gasket is to check the engine compression using a compression tester. If the compression test reveals a low compression reading in one or more of the cylinders, it may be caused by a blown head gasket which allows the pressure to escape. A compression tester is a tool that can measure the pressure of each cylinder of the engine, by connecting it to the spark plug hole and measuring the pressure, the results will give you an idea if all the cylinders are working at the same level, if one is lower than the others then it could be a sign of a blown head gasket.

How to Use a Combustion Leak Tester

A combustion leak tester can also be used to check for a blown head gasket. Here's how to use one.

1. To properly perform a test using a chemical on your radiator, you will first need to drain a sufficient amount of coolant from the system to make room for the test fluid. This can be done by locating the appropriate drain valve on your radiator and opening it to allow the coolant to flow out.

2. Once you have made enough space in the radiator, you can then proceed to insert a cylindrical tube into the filler neck of the radiator, much like you would do when using a funnel. The tube should be inserted far enough so that it reaches the bottom of the radiator.

3. Next, you can pour the test fluid into the radiator through the tube, being careful not to exceed the mark on the tube that indicates the recommended amount of test fluid to use. After adding the test fluid, you should start the engine.

4. Next step will be using a rubber pump, insert it into the tube and begin squeezing the pump to supply oxygen to the radiator. While doing so, you may notice that the color of the test fluid changes over time, possibly turning yellow. This is a confirmation of the presence of bubbles in the radiator and shows the initial observation of a potential issue.

Check Prices of a Combustion Leak Tester

How Much Does It Cost to Replace a Head Gasket?

The cost to replace a head gasket can vary greatly depending on the make and model of the vehicle, as well as the location of the repair shop.

On average, it can cost anywhere from $1000 (£750, €830) to $2000 (£1500, €1660) to replace a head gasket.

However, if the damage is severe and other components need to be replaced, the cost can be much higher.

Conclusion

Determining whether your car is experiencing problems related to a clogged radiator or a blown head gasket can be challenging, as both problems can have similar symptoms.

However, by paying attention to the signs of each problem and knowing how to diagnose and fix them, you can take the necessary steps to keep your car running smoothly.

Remember, regular maintenance is the key to avoid these issues or at least minimize the cost. Always consult professional if you suspect any issues.

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