5 Surefire Ways to Identify a Blown Head Gasket

Blown head gasket

Your car’s head gasket is a critical component that seals the combustion chamber and prevents coolant and oil from mixing. A blown head gasket can cause a variety of problems, including overheating, coolant leaks, and oil contamination. If you suspect that your head gasket may be blown, it’s important to have it checked as soon as possible.

There are a few different ways to check for a blown head gasket. One common method is to check for exhaust gases in the coolant. This can be done by using a combustion leak tester, which is a device that measures the presence of hydrocarbons in the coolant. If there are exhaust gases in the coolant, it’s a sign that the head gasket is leaking.

Another way to check for a blown head gasket is to look for coolant leaks. Coolant leaks can occur around the head gasket, as well as at other points in the cooling system. If you see any coolant leaks, it’s important to have them repaired as soon as possible to prevent further damage to your engine.

Symptoms of a Blown Head Gasket

When the engine is running, a blown head gasket results in the escape of combustion gases. These gases can leak into various areas of the engine, causing a variety of symptoms. Here are the most common indicators of a blown head gasket:

1. Overheating Engine

As combustion gases leak into the engine’s coolant system, the coolant’s ability to absorb and dissipate heat is compromised. This can lead to excessive engine temperatures, which if left unchecked, can cause major engine damage.

The symptoms of an overheating engine include:

High engine temperature gauge reading
Steam or coolant leaking from the engine
Engine knocking or pinging
Loss of engine power

2. White or Milky Oil

Combustion gases leaking into the engine’s oil system can contaminate the oil, turning it white or milky in appearance. This indicates that coolant has mixed with the oil, which can lead to lubrication problems and engine damage.

3. Rough Idle or Misfires

Leaking air or combustion gases can disrupt the engine’s combustion process, causing rough idle or misfires. The engine may run unevenly, hesitate when accelerating, or experience a loss of power.

4. Coolant Leaks

A blown head gasket can create pathways for coolant to leak from the engine. This can result in low coolant levels, which can lead to overheating if not addressed promptly.

5. Exhaust Smoke

In some cases, combustion gases can leak into the engine’s exhaust system, causing white or blue smoke to be emitted from the exhaust pipe. This indicates that coolant or oil is being burned in the engine.

Visual Inspection of Engine

Begin by checking the engine for any signs of external coolant leaks. Look for drips or puddles of coolant around the engine, especially near the head gasket area. Also, check for any white or milky residue on the engine, which could indicate a blown head gasket.

Inspect the oil dipstick and oil cap for signs of coolant in the oil. If coolant has leaked into the oil, it will appear as a milky substance on the dipstick or oil cap. This is a clear indication of a blown head gasket.

Detailed Examination of the Head Gasket Area

Using a flashlight, carefully examine the head gasket area for any signs of damage. Look for cracks, bulges, or other irregularities in the gasket material. Also, check for any signs of coolant or oil leaking from the gasket area.

Specific Signs of a Blown Head Gasket

Sign	Description
External coolant leak	Drips or puddles of coolant around the engine, especially near the head gasket area
White or milky residue on the engine	Indications of coolant leaking onto the engine
Milky substance on the oil dipstick or oil cap	Clear signs of coolant leaking into the oil
Cracks or bulges in the head gasket	Physical damage to the gasket material
Coolant or oil leaking from the gasket area	Visible signs of a breach in the gasket

Performing a Cylinder Pressure Test

The cylinder pressure test provides a more accurate measure of the cylinder’s health compared to the compression test. This test involves using a pressure gauge to measure the cylinder’s pressure during the compression stroke. A blown head gasket will often cause a noticeable drop in pressure, making it an effective diagnostic tool.

How to Perform a Cylinder Pressure Test

1. Prepare the Engine

Start by disconnecting the spark plugs and disabling the fuel injection system. This will prevent the engine from starting during the test.

2. Install the Pressure Gauge

Thread the pressure gauge into one of the spark plug holes. Ensure a tight fit to prevent leaks.

3. Crank the Engine

Have an assistant crank the engine for several seconds while observing the pressure gauge. Note the maximum pressure reached.

4. Analyze the Results

Compare the pressure readings from all cylinders. A blown head gasket will typically result in:

Symptom	Cause
Low pressure in one cylinder	Leakage of combustion gases into the cooling system or exhaust
High pressure in one cylinder	Leakage of coolant or oil into the combustion chamber
Wide variation in pressure between cylinders	Multiple head gasket leaks or severe engine damage

Using a Carbon Monoxide Detector in Radiator

A carbon monoxide detector can be used to check for a blown head gasket by testing for the presence of carbon monoxide (CO) in the radiator. CO is a gas that is produced when fuel burns incompletely, and it can leak into the cooling system if the head gasket is blown. To use a carbon monoxide detector to check for a blown head gasket, follow these steps:

Start the engine and let it idle for a few minutes.
Insert the carbon monoxide detector into the radiator.
If the detector alarms, it indicates that there is CO in the cooling system, which could be a sign of a blown head gasket.

It’s important to note that a positive result on a carbon monoxide detector test does not necessarily mean that the head gasket is blown. Other factors, such as a rich fuel mixture or a faulty exhaust system, can also cause CO to leak into the cooling system. To confirm a blown head gasket, further testing, such as a compression test or a leak-down test, may be necessary.

Additional Information

Symptom	Possible Cause
White smoke from the exhaust	Coolant leaking into the combustion chamber
Bubbles in the radiator	Combustion gases leaking into the cooling system
Loss of coolant	Coolant leaking into the combustion chamber or externally
Overheating	Coolant not circulating properly due to a blocked head gasket

Examining Engine Oil for Contamination

A blown head gasket can allow coolant to leak into the oil passages, contaminating the oil. To check for contamination, follow these steps:

1. Warm up the engine and let it idle for a few minutes.

This will allow the oil to circulate and any coolant contamination to become more visible.

2. Remove the oil dipstick and check the oil level.

If the oil level is low, add oil until it is at the proper level.

3. Examine the oil for any signs of contamination.

Look for the following signs:

Sign	Indication
Milky or frothy oil	Coolant contamination
Brown or black oil	Severe contamination

4. If you see any signs of contamination, stop driving the vehicle immediately.

Further driving can cause severe engine damage.

5. Have the head gasket inspected and replaced as soon as possible.

A blown head gasket can cause major engine damage, including engine failure. It is important to have the gasket replaced promptly to prevent further damage.

6. Check the radiator for any signs of oil contamination.

If the radiator fluid is contaminated with oil, it indicates that the head gasket is blown. To check the radiator fluid, follow these steps:

Allow the engine to cool completely.
Open the radiator cap (be careful, as it may be hot).
Examine the radiator fluid for any signs of oil. If you see any oil droplets or a milky appearance, it indicates that the head gasket is blown.

Pressure Loss Test on Cooling System

This test involves pressurizing the cooling system to identify any potential leaks or weaknesses. It is typically performed using a cooling system tester or a compression tester.

Required Equipment

Item
Cooling system tester or compression tester
Leak detector solution
Gauge

Procedure

1. Ensure that the engine is cool and the cooling system is full of coolant.
2. Attach the cooling system tester or compression tester to the radiator cap or a dedicated test port on the cooling system.
3. Pump pressure into the cooling system using the tester or compressor.
4. Observe the gauge to monitor the pressure reading.
5. Allow the pressure to stabilize for a few minutes.
6. Inspect the cooling system visually for any leaks or weeping fluid.
7. If the pressure drops significantly over time (usually more than 5 psi per minute), it indicates that there is a leak in the system. To pinpoint the source of the leak, spray leak detector solution around potential leak points while the system is pressurized. The solution will bubble or foam if it encounters a leak.

Sniff Test for Combustion Gases in Coolant

This test identifies if combustion gases are leaking into the cooling system. Use extreme caution as the coolant may be extremely hot or even boiling. The results of the test are most accurate when the engine is warm.

Materials:

Coolant reservoir
Paper towel or tissue
Assistant (optional)

Instructions:

Place a few drops of coolant on a clean paper towel.
Hold the paper towel close to your nose and inhale deeply.
Repeat steps 1 and 2 with fresh coolant until you have a good baseline for the normal smell.
If the coolant smells sweet or pungent, it may be contaminated with combustion gases.
Start the engine and let it idle.
Remove the radiator cap cautiously, wearing gloves to avoid burns.
Insert the paper towel into the coolant reservoir.
If the paper towel quickly becomes moist or bubbles, it indicates a potential blown head gasket.

Table: Common Head Gasket Failure Symptoms

Symptom	Indication
White or foamy substance in coolant	Combustion gases leaking into coolant
Oil in coolant or coolant in oil	Coolant and oil passageways compromised
Overheating engine	Cooling system compromised
Rough idle or misfiring	Compression issues caused by head gasket damage
Exhaust smoke	Combustion gases leaking into the exhaust system

Chemical Test for Combustion Gases in Coolant

The chemical test for combustion gases in coolant is a reliable method for detecting the presence of a blown head gasket. This test works by identifying the presence of combustion gases, such as hydrocarbons and carbon monoxide, in the coolant. These gases are released when the combustion process leaks into the cooling system, indicating a breach in the head gasket.

To perform the chemical test for combustion gases in coolant, you will need a combustion gas test kit. These kits typically contain a reagent that changes color when exposed to combustion gases. The test is conducted as follows:

1. Start the engine and allow it to run at idle for a few minutes.
2. Open the radiator cap (or coolant reservoir cap) and insert the test tube into the coolant.
3. Squeeze the reagent bulb and release a few drops of reagent into the test tube.
4. Observe the color of the test tube. If the reagent turns blue, it indicates the presence of combustion gases in the coolant, suggesting a blown head gasket.

Here are some additional details about the chemical test for combustion gases in coolant:

The test is most sensitive when the engine is hot and the cooling system is pressurized.
A false positive result can occur if the engine has recently been run with a rich fuel mixture.
A false negative result can occur if the head gasket leak is very small.

If the chemical test indicates the presence of combustion gases in the coolant, it is highly likely that the head gasket is blown. Further diagnostic steps, such as a compression test or leak-down test, may be necessary to confirm the diagnosis.

Test Result	Possible Cause
Reagent turns blue	Combustion gases present in coolant, indicating a blown head gasket
Reagent remains yellow	No combustion gases detected, or the test was not performed properly

Seeking Professional Diagnosis

If you suspect a blown head gasket but cannot diagnose it definitively yourself, it is essential to seek professional assistance from a qualified mechanic. Here are some reasons why professional diagnosis is crucial:

Accurate Assessment: A mechanic can accurately diagnose the cause of the symptoms using specialized equipment and experience, ensuring a precise diagnosis.
Proper Repair: A professional can determine the severity of the damage and recommend the appropriate repair options, ensuring the problem is addressed correctly.
Avoid Further Damage: If a blown head gasket is left unrepaired, it can lead to catastrophic engine damage. Seeking professional help promptly can prevent such costly consequences.
Cost-Effective: Ignoring the problem or attempting self-repair can result in higher repair costs in the long run.
Warranty Protection: If the vehicle is under warranty, seeking professional diagnosis ensures proper documentation and preservation of warranty coverage.

Diagnostic Tests
Compression test
Leakdown test
Chemical test using a head gasket detector
Cylinder bore inspection

By seeking professional diagnosis, you can benefit from their expertise, receive an accurate diagnosis, and avoid costly consequences. Prompt attention is vital in addressing a blown head gasket and ensuring the longevity and performance of your vehicle.

How To Check For Blown Head Gasket

A blown head gasket is a serious problem that can cause your engine to overheat and even seize up. It’s important to be able to check for a blown head gasket so that you can catch it early and prevent major damage.

There are a few different ways to check for a blown head gasket. One way is to look for coolant leaks. A blown head gasket can cause coolant to leak from the engine, so if you see any coolant leaks, it’s important to have your engine checked by a mechanic.

Another way to check for a blown head gasket is to look for exhaust gases in the coolant. A blown head gasket can allow exhaust gases to leak into the coolant, so if you see any bubbles in your coolant, it could be a sign of a blown head gasket.

Finally, you can also check for a blown head gasket by performing a compression test. A compression test measures the amount of pressure in each of your engine’s cylinders. If one of your cylinders has significantly lower compression than the others, it could be a sign of a blown head gasket.