Top 5 Best Head Gasket Sealers (2020 Review)

Are you looking for the best head gasket sealers? You've come to the right place!

In this guide, you'll learn:

  • What head gasket sealers are
  • What the different types of head gasket sealers are
  • How head gasket sealers work

And much more!

Top 5 Best Head Gasket Sealers (2020 Review)
Image Product


K-Seal ST3501 Pour and Go Permanent Head Gasket and Block Repair
  • Easy to use
  • Can be added to overflow tank
  • Anti-rust
  • Easy to use
  • Can be added to overflow tank
  • Anti-rust
View on Amazon


K&W 401016 Metallic Block Seal
  • Stops leaks
  • Repairs gaskets
  • Easy to apply
  • Stops leaks
  • Repairs gaskets
  • Easy to apply
View on Amazon


Bar’s Leak HG-1 Head Seal
  • Seals warped heads
  • Stops overheating
  • Reinforced with carbon fiber
  • Seals warped heads
  • Stops overheating
  • Reinforced with carbon fiber
View on Amazon


BlueDevil Pour-N-Go Head Gasket Sealer
  • Permanent repair guarantee
  • Made in the U.S.A
  • DIY friendly
  • Permanent repair guarantee
  • Made in the U.S.A
  • DIY friendly
View on Amazon


Hi-Gear HG9048s Insta-Seal Permanent Block Sealer
  • Permanent block
  • Also works as radiator seal
  • No draining required
  • Permanent block
  • Also works as radiator seal
  • No draining required
View on Amazon

Overall #1 Rated Pick

Updated As of 5/26/2020

  • Easy to use
  • Can be added to overflow tank
  • Anti-rust

Our top pick is this incredible K-Seal head gasket repair formula because it's such a workhorse!

This sealer will permanently fix blow head gaskets, cracked heads, and stops leaks immediately.

Not only is it incredibly durable, it's also incredibly fast and easy to use!

This stuff will help you repair even the most difficult leaks and cracks, so if you want the best, look no further!

Discovering that your engine is suffering from the effects of a head gasket leak never comes as welcome news, as your head gasket plays an intricate part in ensuring that your engine runs as it should.

Head gasket replacement is time-consuming, and never easy on the wallet.

For those faced with the prospect of replacing their engine's head gasket, the use of a quality head gasket sealer is often the only alternative solution to heading down the rabbit hole of excess expenditure of both time and money.

 So how are you to choose the best sealer for a quick head gasket fix? Luckily, we have just the answers that you are looking for!

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Top 5 Best Head Gasket Sealers

Check out our below list for a summary of our results. Keep on reading to learn more about your other options!

What Are Head Gasket Sealers?

To understand the overall purpose of today's head gasket sealer products, you must first understand the immensely important role that a head gasket plays in your engine's day-to-day operation.

Internal combustion engines, such as the one that powers your vehicle, are comprised of two major structural segments. 

These segments are known as the engine block and cylinder heads. Each of these two components is essential for engine operation, and without either of the two, your engine stands no chance of running.

Engine Block

An engine block is a large cast assembly that is typically constructed of cast-iron or aluminum, and houses your engine's cylinders, pistons, crankshaft, and camshaft (in the case of overhead valve engines).

This entire assembly is often known collectively as an engine's "bottom end." The engine block also contains coolant jackets and oil passages to maintain thermal integrity and component lubrication.

Combustion also takes place within the cylinders that are contained inside of the engine block.

This combustion cycles the piston in each respective cylinder, thereby transferring power to the crankshaft.

Cylinder Head

The Cylinder head(s) resides atop the engine block, containing an engine's valvetrain. This entire assembly is often known collectively as an engine's "top end."

This valvetrain is timed to the lobes of the camshaft by way of the engine's lifters. As the valves contained within the cylinder head open and close, air is allowed into each cylinder, and exhaust gases are expelled.

The head essentially caps each cylinder, containing compression as specified. To further study cylinder head specifics, check out this link.

head gasket's purpose is to seal the connection between an engine's block and cylinder heads. This keeps coolant, oil, and compression/combustion gasses from mixing.

A failed head gasket caused by overheating or warped heads can lead to dire consequences regarding your engine's health. 

A failed head gasket that is not repaired promptly only further exacerbates these issues, possibly leading to more extensive damage in the long run.

For more on head gaskets, follow this link

The following are common indications that you might be experiencing the effects of a failed head gasket.

If any of the following symptoms are observed, further diagnostics should be conducted to verify a leaking head gasket as the culprit.

  • White Exhaust Smoke- A blown head gasket often leads to a steady amount of white smoke being emitted from your car's exhaust. When this is observed, it typically indicates that coolant is entering one or more of your engine's cylinders. This smoke comes as a result of your engine attempting to combust the misdirected coolant.
  • External Leaks- If a fluid leak at the seam between the engine block and cylinder heads becomes evident, you are likely dealing with a blown head gasket. Either oil, coolant, or a mixture of the two can be expelled when a head gasket has failed.
  • Frothy Engine Oil- When a head gasket fails, oil and coolant often come into contact with one another. If coolant makes its way into your engine's oil, a milky or frothy substance is commonly noted on the oil dipstick or the underside of the engine's oil cap.
  • Milky Coolant- If your coolant reservoir suddenly begins to appear as if it contains a muddy or milky substance, it is highly likely that you are looking at the results of a blown head gasket. Just as coolant can enter an engine's lubrication system when a head gasket has failed, the opposite is also a common occurrence. Oil that has entered the engine's cooling system is typically most evident in the coolant reservoir or sight glass.
  • Overflowing Or Bubbling Coolant- When a head gasket has blown, combustion gasses have the potential to escape into an engine's cooling system. This can cause pressures to build beyond what a cooling system is designed to handle and therefore allow coolant to escape out of a vehicle’s pressurized radiator cap.
  • Poor Engine Performance- If your vehicle’s engine is losing compression as the result of a head gasket leak, it will not run at a peak level of performance. This is especially true if the gasket is blown between two cylinders.

To address the issue of a blown head gasket, the leak must be repaired. This is often accomplished through the removal of an engine’s head, or heads, and the replacement of the compromised gasket. 

However, this is not a job for the faint of heart, and taking your car to a service center for head gasket repair can get very expensive, very quickly.  

Check out this link for more on the effects of a cylinder head gasket failure.

This is where the use of a quality head gasket sealer comes in.

Head gasket sealer is a product that, when applied, bonds to the sealing surface of a head gasket and patches the compromised segment in order to remedy the issue at hand with a high success rate. 

With any luck, you will be back on the road in no time, avoiding costly repairs and inconvenient downtime.

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What Are The Different Types Of Head Gasket Sealer?

While the bulk of head gasket sealers on today’s market are intended for similar use, there are some differences between these various products.

Much of these differences come down to the exact chemical that is used in a particular application, as well as the procedure that is used to apply the product.

Some manufacturers claim to use a carbon fiber solution in their mixture to fill in the damaged segment of gasket material. Others state that their products consist of a resin that forms a “glass-like” compound when applied and allowed to harden. 

When it comes to the procedure of applying head gasket sealer, there are typically two schools of thought among manufactures. Several head gasket sealers are designed to be used without draining a vehicle’s antifreeze from the cooling system. 

On the other hand, an equal number of manufacturers specify that the cooling system must first be drained before the application of their product.

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Did you know: According to Mobil Oil, the most common cause of head gasket failure is your engine overheating.

How Does Head Gasket Sealer Work?

Head gasket sealer works by infiltrating the damaged sections of an engine’s head gasket, where it then forms a secondary seal to fill the void.

To complete this process, a bottle of sealer is poured directly into the engine’s cooling system via the radiator neck or overflow reservoir. 

Once the sealer has entered the system, it is circulated by the engine’s water pump.

As this sealer travels through the system, it naturally finds the leak-prone areas in the component sealing surfaces, just as the leaking fluid does itself.

As the head gasket sealer begins to filter into the site of the leak, it starts to set-up, where it bonds to the remaining structure of the head gasket and begins to cure in place.

If the process is successfully completed, the leak within the gasket is sealed, and fluids can no longer be displaced from their point of origin. Read this article for more on how to use head gasket sealer.

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What Do You Look For In The Best Head Gasket Sealer?

When choosing the best head gasket sealer to rescue you from your mechanical woes, it is of great importance to only purchase those products that are manufactured by reputable sources.

There are a near-limitless number of head gasket sealers on the market today, all of which seemingly claim to perform miracles.

By staying away from obscure off brands, you are less likely to be stuck with the purchase of “snake oil”, so to speak.

It is also immensely important to consider the personal experiences of others when purchasing head gasket sealer.

Since a sealer of this nature is not a product that you can physically watch in action, you must put your trust in your chosen sealer and keep your fingers crossed that it works. 

You will only receive confirmation that your attempt has been a success after some time on the road.

To lessen the apprehension toward the purchase of a particular head gasket sealant, it pays to weigh the first-hand experiences and reviews of others into your buying decision.

Yet another point for consideration when purchasing a head gasket sealer is what kind of warranty is offered by the manufacturer of a particular product. A number of sealant companies offer money-back guarantees on their product. 

It can often be wise to consider such warranties because it would not take long for a company to go under if a warranty of this nature was offered in conjunction with a product that was ineffective.

If a company stands behind its gasket sealer to the point of offering a money-back guarantee, it is often for good reason.

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Best Head Gasket Sealers Reviewed

With the numerous head gasket sealers on the market today, it practically goes without saying that some of these products are naturally better than others.

When attempting to locate a remedy for a problem as dire as a blown head gasket, you need nothing short of the best.

The following are our top picks for the best head gasket sealers.

K-Seal ST3501 Pour and Go Permanent Head Gasket and Block

Repair is engineered to minimize downtime and maximize results.

Perhaps the most notable characteristic of this sealer is that you simply pour and go. 

No draining coolant or flushing your radiator and engine is necessary. 

By simply pouring this product into your radiator or overflow tank, no matter the operating temperature, you can simply go about your business, allowing the block to seal as you go.

The performance claims of this product have also been validated through testing at Brighton University.


  • Easy to install, pour and go formula
  • Scientifically tested to verify claims toward coolant leak repair
  • Works on both hot and cold engines


  • A limited number of consumers report developing a clog in their heater cores, radiators, or thermostats.

K&W 401016 Metallic Block Seal is quite possibly the most cost-effective way to seal a leaking head gasket that exists on the market today.

With its minimal cost and high potential, there is little reason not to give this product by K&W a try. 

This sealer meets the ASTM D6107 industry standard for coolant system leak sealing, and is also capable of sealing cracked engine blocks and leaking radiators. 

This product can also be used with both gasoline and diesel engines.


  • Permanent solution for leaking gaskets
  • For both gasoline and diesel engines
  • Exceeds industry standards for cooling system repair


  • Coolant must be drained from the system prior to use to ensure that this product works

Bar's Leak HG-1 Head Seal is designed to meet the demands of those that need their vehicle back on the road sooner rather than later, and would rather bypass the outright expense associated with head gasket replacement.

This product also comes from a reputable source for all things gasket sealer. 

No engine flushing is required with this product, and its carbon-fiber composition stops leaks quickly and permanently. 

Bar’s Leak products have been around for many years and have a reputation for high overall quality.


  • Single application repair of minor leaks
  • Also repairs leaking freeze plugs, heater cores, radiators, intake gasket seal leaks, and cracked heads.
  • Lifetime Warranty


  • Though not mandatory, a radiator flush prior to use comes recommended by a number of consumers.

BlueDevil is yet another name that is synonymous with a long history of top-notch leak sealer products, and the Pour-N-Go Head Gasket Sealer does not stray from this storied tradition.

The BlueDevil Pour-N-Go Head Gasket Sealer, does exactly as its name implies. 

Simply add the contents of the bottle to your engine’s cooling system and drive away. 

Within just a short time, your engine will be sporting a permanent seal to its once leaking head gasket.


  • Permanent repair
  • Simple pour and go application process
  • Manufacturer guaranteed


  • 8-cylinder applications can require more than one bottle

Hi-Gear HG9048s Insta-Seal Permanent Block Sealer is another excellent option for those saddled with the burden of a leaking head gasket while operating on a restrictive budget.

This sealer utilizes a combination of micro-fibers and copper that reacts with the engine’s heat to fuse and bridge the gap between blown segments of a head gasket. 

This reaction leads to a permanent bond, that alleviates all concerns toward your compromised gasket moving forward.

No draining of coolant is required, and this product is compatible with all antifreeze types.


  • Compatible with all anti-freezes
  • Will not void manufacturer warranty
  • Creates permanent seal


  • A small amount of sealer per bottle

This is without a doubt one of the most highly renowned head gasket sealers on the market today.

With its independently verified functionality and a price point that should be comfortable for most vehicle owners, I feel that K-Seal ST3501 is a superior product that gives you the best possible shot at repairing your engine’s leaking head gasket without internal repairs. 

If I was betting the health of my engine on any of today’s head gasket sealers, my money would be on K-Seal ST3501.

About Your Mechanic

About Josh Boyd

I’ve been an ASE Certified automotive/heavy equipment technician since 2010. I began my career performing basic automotive maintenance at a service center before working as a Toyota technician at my local dealership.

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