What is a Head Gasket Sealer and How Does it Work?

When your car is new, you have nothing to worry about. On the other hand, when you’ve got quite a few miles (75,000 or more) on your automobile, it’s another story. At that stage, it’s likely to start giving trouble. This is when you need to be vigilant of any warning signs your car may show, and do timely repairs. Head gasket failure is one such trouble your car may show early warning signs of. It’s better to fix the issue before things get worse. You definitely don’t want to end up with a hooptie parked on your driveway!

What is a Head Gasket Sealer
What is a Head Gasket Sealer

The warning sign …

When you see white smoke coming out of your car engine, it’s highly likely the head gasket is blown away. Besides the smoke and head gasket leak, there are various other symptoms to confirm this.

At first, finding out your head gasket has blown can be quite worrisome. Feeling worried is natural, as the replacement of car parts is expensive, and a head gasket replacement is no exception.

Why you shouldn’t worry…

The best head gasket sealer can take care of the problem without digging a hole in your pocket. Typically, head gasket replacement costs can fall in the region of $1500 to $2000, if not more. The best head gasket sealer can take care of the problem at a small fraction of that cost. Thus, the head gasket repair cost is significantly lower than the replacement cost.

In this guide, we will take you through the nitty-gritty of the head gasket, blown head gasket, the head gasket sealer, and the best head gasket sealant brands. Finally, we will recommend our picks of the 10 best head gasket sealer products available to purchase in 2023. Read through, to find out which head gasket sealer is best suited for your car and why.

What is a Head Gasket?

Before moving on, it’s important to know what a head gasket is; to appreciate why it’s a crucial part of the engine and engine performance. Remember, a healthy engine equates to healthy car life.

In a car’s internal combustion engine, between the engine block and cylinder head(s), lies a critical component – the ‘head gasket’. The engine block houses the pistons and cylinders, and the cylinder head is where the rocker arms and valves reside. The head gasket, which lies between these two engine parts, is the most critical sealing application of an engine.

Its purpose…

Its purpose is to seal the cylinders to allow the greatest possible compression, while simultaneously preventing leakage of coolant, or engine oil, into the cylinders. Building proper compression and containment of exhaust gases results in optimal engine efficiency. That is why a sealed combustion chamber (of the engine) is a critical engine design feature.

The head gasket’s critical functionality makes it the most stressed gasket in an engine. For this reason, it is also the most prone to failure. Every car engine has this gasket, what varies is the thickness and construction. The variation depends on the engine design unique to the car model and manufacturer.

How to tell if a Head Gasket is Blown?

There are a handful of symptoms that can indicate a car has a blown head gasket. These symptoms fall between two categories; the obvious, and the relatively subtle.

Read More:- BlueDevil Head Gasket Sealer Review & Instruction

Why Do You Need a Head Gasket Sealer?

Head Gasket Sealer…

A head gasket sealer (gasket sealer) is the do-it-yourself method to effectively fix the blown head gasket. Products available in the market come in the form of a paste, glue, or spray. The question, why you need the sealer, takes us back to the basic premise of a blown head gasket and the difficulty and expense associated with replacement.

The Value Proposition…

Reiterating the basics; a blown head gasket is quite worrisome to a car owner. Multiple problems arise leading to engine overheating: contamination of fluid (coolant mixed with oil), engine misfires, and oil leaks. Replacing the head gasket is an expensive affair, leaving you with the best possible option of purchasing affordable head gasket sealers.

The best sealer available in the market effectively keeps your gasket in place. They combat fluid leakage, plug cracks, and prevent car parts from rubbing against each other.

We stress the ‘best’ sealers because only the very best will not wear out prematurely. The trick is to apply the best sealer for your car – correctly.

Does a Head Gasket Sealer Really Work?

Above Video Credit goes to Mustang LifeStyle YouTube Channel

The answer to this question depends on the brand and product you choose and how well you apply it. So the answer is “yes”, but it’s a different ” eyes” for every situation.

The fix is temporary but worth it, depending on how long it extends the life of your car. So, really, the fix may last for some weeks or some years. Asking, “how long does a head gasket sealer work before the gasket fails again?”, is the more pertinent question.

Here are the factors you must consider while determining which sealer works best for your car.

Factors to consider …

  • Find out where and how your head gasket failed.
  • Determine which gasket sealers are most compatible with your car model.
  • Determine whether the sealer applied failed to fix the leak on the first attempt and whether after a short period of time the coolant leak eventually returned.
  • Do a comparison of various head gasket sealers before deciding the best one for your car model.

The bottom line here is that head gasket repairs are very expensive, so a sealant is definitely worth trying. After applying a head gasket sealer, check back after a few days to see if there are any more leakages and any occurrence of overheating in your car. If not, then things are working out fine.

Read More:- Best Head Gasket Sealers of 2023

How to Replace a Head Gasket?

How to Replace a Head Gasket
How to Replace a Head Gasket

Replacing a head gasket involves the following approach:

  • Confirm that the head gasket is blown or faulty
  • Drain out both coolant and oil from the engine, completely
  • Remove the cylinder head and all the associated components
  • Carefully inspect and clean the removed components
  • Remove the head gasket
  • Inspect the engine block thoroughly, looking for any signs of damage
  • Fix the new head gasket and apply the best-suited sealant
  • Reinstall the cylinder head and associated components correctly; in accordance with their original specifications
  • Fill the engine with fresh oil and coolant
  • Run the engine and check to see if there are any leaks or issues
  • Do a final Road test of the vehicle

In the above approach, a preliminary investigation is of importance because the issue could also be a rocker cover issue, an exhaust issue, a cooling system failure, or another problem.

How Does a Head Gasket Sealer Work?

The head gasket sealer starts to do its job once you pour it into the radiator and then run your engine for 20 to 50 minutes. While running your car, make sure the heater and fan are on, and set on high, as the chemicals in the sealant work via heat. During this process, the sealant chemicals make their way, fitting into cracks and gaps in the blown head gasket. Eventually hardening to complete the repair.

How much sealant to pour inside the radiator depends on the size of your engine. An eight or ten-cylinder vehicle will require more sealant than a four or six-cylinder vehicle.

Here are the steps on how to use the head gasket sealer.

Read More:- Top Head Gasket Sealer Brands With Our Ratings

How to Use Head Gasket Sealer?

  1. Jack the vehicle up
  2. Place a container under the radiator. The car’s instruction manual will reveal coolant volume capacity, so fetch a container big enough not to overflow.
  3. Locate the petcock on the radiator and use a wrench to open it.
  4. Drain out the coolant into the container you’ve placed underneath the radiator. Once fully drained, close the petcock.
  5. Fill water into the radiator. Note, that a damaged or worn-out radiator cap should be replaced.
  6. Disconnect the thermostat so that the coolant doesn’t engage while the sealer is being added.
  7. Start your vehicle while your heater and fan are set on high. This ensures the water can circulate through the system and drain any remnants of the coolant.
  8. Keep an eye on the temperature gauge, and turn off the engine in case it overheats.

Next, the steps to fill the system with the head gasket sealer…

  1. Re-open the petcock and drain out the water completely (the water is contaminated) into a container, just like you drained out the coolant in step 4 above.
  2. Close the petcock
  3. Reconnect the previously disconnected thermostat.
  4. Mix coolant and water in a 50/50 ratio into the reservoir. The coolant should be suited to your vehicle. Pour it in until it reaches maximum capacity.
  5. Now pour the head gasket sealer into the radiator, as per the head gasket sealer instruction manual.
  6. Close the radiator cap. Drive your car around for around 20 to 50 minutes, to allow the sealer to navigate through the entire system before reaching the head gasket.
  7. Stop your car after 20-50 minutes have passed, or earlier if the vehicle starts overheating.
  8. Let your car rest for a few hours.
  9. Evaluate whether the leakage in the blown head gasket has healed; by checking “blown gasket symptoms”, as mentioned earlier.
  10. If no symptoms appear (hopeful outcome), and your car performs well, your head gasket sealer has fixed the issue. However, if the leakage still persists (slim chance), then you’ll have to replace the head gasket.

Benefits of Head Gasket Sealer

There are several benefits of head gasket sealers. The biggest benefit is that the sealer looks for leaks and seals them off. By sealing the leak you won’t have to get your head gasket replaced. You can enjoy driving your car without investing in heavy mechanical work. It’s a quick do-it-yourself fix that prolongs the life of your car.

Besides being a quick, easy, and economical solution to fix a leakage in a faulty head gasket, a head gasket sealer has the added advantage of being a multi-purpose product. Some products can be used on other leaks that affect the engine performance. For example, a high-grade sealer can solve problems related to the heater core and bad freeze plugs.


How Much Does it Cost to Replace a Head Gasket?

A head gasket replacement can cost anywhere between $1500 to $2000+. It’s a highly labor-intensive process, whereby the average mechanic charges anywhere from $30 to $65+ per hour. In fact, most of the blown head gasket cost of replacement (70%) can be attributed to labor alone; it takes 10+ hours to do the job.

How long does the head gasket sealer last?

A head gasket sealer can last 3 weeks or 3 years. It all depends on your car’s age, make, and condition; which sealer you selected; how you applied the sealer; and how vigilantly you check leakages. Primarily, the secret lies in the sealer you use. The best products in the market are known to effectively fix the leaks and prolong the life of the engine.

Can the head gasket sealer damage the engine?

Judging by internet forums and reviews, you’ll find proponents of the product swinging either way. That’s because everyone has used a different approach. Some of them have been wrong in product selection, others have wrongly diagnosed the symptoms and associated them with head gasket failure. Doing so and applying the sealer unnecessarily, can lead to engine damage.

Eventually, it comes down to choosing the best head gasket sealer for your car and its condition. If you match the product and issue right, you’ll achieve success!

Bottom Lines

When it comes to a blown head gasket, more often than not, it’s recommended that you fix the issue with a recommended head gasket sealer. If your car is old, you wouldn’t want to spend a fortune on replacing a part, when an economical quick fix is available as a viable option.

We recommended the Steel Seal Blown Head Gasket Fix Repair Sealer as our top pick for the best head gasket sealer. It’s as close as you can get to a permanent head gasket fix without replacement. It works well on older and new vehicles and is suitable for cars, vans, SUVs, and trucks. However, any one of the other brands on our list will equally do the job, depending on your car’s model, age, specific condition, and budget.

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