How to Test a Blown Head Gasket

How to Test a Blown Head Gasket

Between the engine block and the cylinder head, there is a head gasket. You might not be very familiar with this component of your car’s operation if you aren’t a mechanic or a DIY auto enthusiast. Its main function is to seal the engine’s internal combustion system and stop coolant and oil from mixing as they move from the engine block to the cylinder head. The head gasket may start to leak since it is constantly exposed to hot and cold conditions. Fortunately, there are warning signs that lead to head gasket issues.

How to Test a Blown Head Gasket

Today, we’ll be looking at how to test a blown head gasket. We’ll also be discussing the signs of a bad head gasket and how much it will cost to replace the head gasket in your car.

Read more: Most Common Signs and Symptoms of a Blown Head Gasket

Alright then, let’s get to it!


How to test a blown head gasket

Here are things to do when diagnosing a blown head gasket:

Examine Your Engine Oil

Examining your engine oil is one of the simplest and most reliable techniques to determine if you have a blown head gasket. You can check it by lifting the dipstick, but draining the oil from the pan and looking is much more effective if you’re on the point of needing an oil change. It’s a sign of a blown head gasket when engine oil and coolant mix. If your oil has a milky hue rather than the dark brown or black of old oil, it is mixed. The color will be milkier the more coolant is present.

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Since your coolant is a sealed system, everything you put in it should stay there. And even though the levels may occasionally change somewhat due to variations in pressure and temperature, however, they should basically be constant. There is an increased chance that your coolant is leaking within your engine if you find that you need to continually add coolant to the system despite the lack of a visible leak. If there is too much smoke, it enters the combustion chamber, and if there is milky-colored oil, it enters the oil channels.

Additionally, if there is oil in the coolant reservoir, you’ll notice a foamy or milky appearance that indicates a problem, just like your oil can change color if it’s mixing with the coolant. When the coolant cap is removed and smoke is seen coming from the coolant reservoir, compression may also be taking place within the coolant system. An exhaust tester can also be used to test this.

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Check Your Spark Plugs

Coolant or oil on your spark plugs is a surefire sign that you have a blown head gasket. Even while this isn’t as simple to find as checking your oil or exhaust, it’s a surefire approach to identifying the issue. Simply remove your spark plugs and give each one a thorough inspection. You have an issue and it’s probably a blown head gasket if you see any oil or coolant residue on the spark plug’s tip.

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Check Your Exhaust

If you see much more smoke coming from your exhaust than usual, you may have a blown head gasket. When diagnosing excess exhaust, there are a few factors you should be aware of. First, expect more emissions than in warmer weather as the outside temperature decreases. This is completely typical and excludes blown head gaskets.

Second, if you have a blown head gasket, you should be on the lookout for excessive white smoke since coolant burns this color when it enters the combustion chamber. Finally, for the issue to be a blown head gasket, there must always be an excessive amount of smoke. The issue is probably not a blown head gasket if the amount of exhaust smoke varies after warming up or on different days.

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Check For Leaks

Fewer people are aware that blown head gaskets can cause external leaks, despite the fact that most people are aware that they can cause fluid to move to other areas of your engine. It all depends on where the leak is. Fluid will drip down the outside of your engine rather than enter various channels if it is closer to the outside of the head gasket.

If it pools up and burns off before it reaches the ground, your engine may emit smoke as a result. Or, if it does fall to the ground, the fluid should start to pool up underneath your car. The only method to determine if this fluid is coolant or oil is to follow the leak’s path back to its origin. You’ve identified the issue if you do discover that the head gasket is the source.

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Inspect the Radiator

When inspecting your radiator, there are a few distinct things you can look for. A blown head gasket will first allow air into the cooling system, which will result in a frothy or foamy mixture in the radiator. Additionally, the system might contain a mixture of fuel and oil. If that occurs, when you examine the radiator, the mixture will have a milky tint.

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Run a Compression Test

This test is one of the trickiest to execute, but it’s also one of the best. To accomplish this, you’ll need a few specialized tools and you’ll also need to remove the spark plugs. Make sure to inspect the spark plugs for any coolant or oil residue before you remove them. If you have a blown head gasket, you’ll notice a decrease in compression in the afflicted combustion chamber. This is due to the fact that the cylinder can never entirely seal, and the extra pressure will always escape. However, this strategy might make it exceedingly difficult to detect small breaches.

Read more:  How to Test a Blown Head Gasket

Signs of a blown head gasket

How to Test a Blown Head Gasket

Here are the most common signs of a blown head gasket:

  • Engine Overheating
  • Milky Build-Up Under Oil Cap
  • Visible Tailpipe Smoke
  • Rough Idle

Engine Overheating

When the engine overheats, you’ll be left wondering which issue came around first. Did the engine overheat as a result of the head gasket leaking into it, or did the hot engine cause the parts to bulge, which then allowed the head gasket to leak? Regardless of what causes the issue, running a car with an overheated engine is a surefire way to end up with an engine failure.

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Milky Build-Up Under Oil Cap

It is simple to determine whether the head gasket on your engine has blown. Simply look under the oil filler cap. The interior of the oil cap should be basically dry if the gasket is good. You probably have a gasket leak if you find a milky, brownish-yellow fluid that resembles the consistency of a milkshake. The milky substance is engine oil contaminated by coolant and oil that has leaked past the head gasket. After becoming polluted, your engine oil is no longer able to adequately protect it. Get a head gasket replacement as soon as you can if you think this may have happened.

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Visible Tailpipe Smoke

The head gasket controls how coolant moves through the engine’s coolant channels. Coolant may seep into the combustion changers, which are close to the coolant channels if the head gasket fails. The liquid will burn alongside gasoline. This causes the tailpipe to continuously emit white or gray smoke. This is a blatant indication that your head gasket is faulty.

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Rough Idle

Between two combustion changers, the head gasket can also degrade. A high-pressure level must remain inside the cylinders of the engine at all times. The engine will run badly and have a choppy idle when the head gasket fails since it won’t be able to maintain the proper level of pressure. A rough idle should not be ignored even though it is not a certain sign of a faulty gasket head.

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Head gasket replacement cost

The average cost of replacing a head gasket is between $1,000 and $2,500, often even more. The price of a head gasket replacement might vary significantly based on the make and model of the car, where you reside, which auto repair shop you choose, and other factors.

This price includes the labor involved in disassembling the engine, swapping out the gasket and other required components, and putting it back together. If necessary, it might also cover the price of resurfacing the engine head.

It’s crucial to remember that replacing a head gasket is a serious repair that calls for a high level of competence; as such, a novice shouldn’t attempt it. Bring your car to a reputable, skilled mechanic who can handle the repair correctly and securely.

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What can be mistaken for a blown head gasket?

Many vehicles frequently experience coolant and oil leaks. You don’t necessarily have a blown head gasket just because you notice a leak. However, if you see that most of the oil or coolant is leaking from the engine block, it can be a sign that the head gasket is no longer keeping a seal.

Read more: Difference between lean burn and rich burn engine

What is the best test for head gaskets?

Checking for the presence of combustion gases in the engine coolant is the most efficient and accurate diagnostic technique to establish whether the cylinder head gasket is sealing combustion gases. When performing this, the radiator cap must be off and the engine must be heated.

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How do I know if my head gasket is cracked or blocked?

When you can see that the engine’s antifreeze has become mixed with the oil, that is a big symptom of a broken engine block or burst head gasket. The circulating engine antifreeze may contaminate the flowing engine oil if there is a fractured block or blown head gasket.

Read more: Understanding Lean Burn Engines

How do you check for a blown head gasket with a pressure tester?

You can see if the pressure in the system remains constant or drops over the course of a few hours once the air source has been cut off. Pressure loss over time is a sign of a leak, so check for it immediately. The likelihood of having a head gasket leak increases if the leak cannot be located externally.

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How does a blown head gasket sound?

Depending on how the head gasket bursts, you can even hear a knocking noise coming from the engine or the sound of a misfire. An overheated engine, a coolant leak, or decreased compression as a result of harsh idling are all possible causes of the sound of a misfire.

Read more: Understanding Cooling Systems in Internal Combustion Engines

How do you fix a blown head gasket without replacing it?

  • Flush the cooling system after removing the thermostat.
  • Add water to the system.
  • As the car idles, slowly add BlueDevil Head Gasket Sealer to the radiator.
  • Place the radiator cap on and give the engine a minimum of 50 minutes to idle.

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Can you seal a blown head gasket?

In a nutshell, yes. However, head gasket sealers are not a long-term cure for a blown head gasket. These products only work temporarily and have a limited shelf life; eventually, wear and tear will need to be repaired for your car to function properly once more.

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Can a car run normally with a blown head gasket?

Yes, in short, but it is not advised. Ignoring a blown head gasket will probably result in more harm to your engine and your finances. The most crucial and essential components of any engine that serve to seal off compartments are gaskets.

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Can a car still run with a blown head gasket?

Driving with a burst head gasket will surely result in other car problems. Before it’s too late, K-Seal can stop the issue in its tracks. Technically, driving with a blown head gasket is possible, but we never recommend it.

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What does exhaust look like with a blown head gasket?

White Exhaust Smoke

If you see white smoke coming from your exhaust, there is probably coolant leaking into the cylinders. The head gasket breach that causes the coolant to produce this white steam most frequently causes this to occur. Have it fixed so that the breach doesn’t continue to grow.

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How long does a blown head gasket last?

The short answer is that they ought to last as long as your engine. However, the likelihood is that you will need to replace the head gasket in your car at some point throughout its lifetime if you don’t properly maintain it or the engine.

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That is all for this article, where we looked at how to test a blown head gasket. We also get to discuss the signs of a bad head gasket and how much it will cost to replace the head gasket in your car. We hope it was helpful. If so, kindly share it with others. Thanks for reading; see you around!