Best Head Gasket Sealer Reviews

There are many perks of owning a car but wear and tear are obvious especially when the maintenance is poor. This can cause plenty of problems in the car, especially in the head gasket, engine, and surrounding parts.

The head gasket is a critical part that prevents fluids like coolants and oil to mix up with one another. But it is vulnerable to sustain cracks and leaks which largely affect its functionality.

Some common car problems caused by a blown-up/damaged head gasket are:

  • Thick white smoke coming out of the radiator or from the exhaust.
  • Engine making hiccup sounds while operational.
  • Decreased engine efficiency.
  • A puddle of fluids spilled on the floor and making a tail.
  • Overheat issues.
  • Frequent engine shutdowns.

To help out people, we have made a list of the 4 best head gasket sealers that pack quite a punch when it comes to repairing a head gasket.

  1. ATP AT-205 Re-Seal Stops Leaks
  2. Bar’s Leak HG-1 HEAD SEAL Blown Head Gasket Repair
  3. K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair
  4. Bar’s Leaks 1111 Head Gasket Fix

A head gasket is a ringed structure panel that sits between the engine and the cylinders so as to avoid any coolants running into the engine and engine oil running into the coolant system. However, a poor-quality head gasket or an old one can blow up with time and fail to function.

In case of a blown-up gasket, most of us turn to a mechanic to get the necessary repairs without even knowing how easy it is to repair a head gasket on our own.

Simply put, the cost of replacing a head gasket ranges from $280 to $400+, plus there’s the labor cost and other charges that can take the price to a high of $1000 or more. That’s a lot of money and not everyone can afford that.

So, let us tell you that there are a handful of other options that can fix such problems and save your hard-earned money.

One simple option is to get a head gasket sealer and repair the gasket yourself.

Head gasket sealers can do a number of wondrous things such as mend cracks and seal leaks.

In this head gasket sealer review, we will shed light on a number of things that every driver must know about. Ths include:

  • What is a head gasket?
  • Signs and symptoms of a blown-up head gasket?
  • Which are the 5 best head gasket sealers that can help fix the problem?
  • We’ll also fill you in with important knowledge on how to diagnose and solve gasket related problems.

It doesn’t matter if you are completely blank on diagnosing common car problems and replacing parts like the head gasket. We’ll make sure you’ll have the right knowledge to repair it yourself.

What Is A Head Gasket?

Blown Head Gasket
Blown Head Gasket

A head gasket is a crucial component of a car. It is a panel with ring-like structures that sits between the engine block and the cylinders. Its function is to separate the cylinder head and engine block so that their fluids don’t run into one another in case of any damage.

A blown-up head gasket won’t be able to hold the fluids in their respective containers and affect the engine’s performance.

What Are Head Gasket Sealers & How Can They Fix A Blown Up Head Gasket?

Head gasket sealers are the ultimate solution to seal leaks, cracks. They can eliminate all the symptoms occurring due to a damaged head gasket.

They may come as paste like or glue like substances or in a liquid form in some cases. They are poured into the radiator along with a coolant system so that the content of the sealer runs along the coolant passage and reaches the places where there are leaks.

These sealers then work their magic and seal all kinds of cracks, holes, leaks, warped heads, antifreeze problems, etc.

Top 5 Head Gasket Sealer Reviews

Since there is a plethora of head gasket sealers on the market that claims to solve gasket problems, it can confuse drivers in picking one that’s best for them.

Let’s get to know each of them in detail now:

ATP AT-205 Re-Seal Stops Leaks

Our top pick is the ATP AT-205 because of the strong results it provides. The best thing about this gasket sealer are that it works on a number of components and eliminates leaks for a long period of time.

ATP AT-205 Re-Seal

Stops Engine Leaks: Engine leaks are common and very dangerous as well. A major reason for them to get a leak is because of a blown up gasket. Luckily, the ATP AT-205 works like a charm in stopping engine leaks.

Most of the gasket sealers work on one type of engine, diesel or gasoline, but that’s not the case with this product. It can work in both diesel and gasoline engines and seal all the leaks.

Stops Leaks In Transmission: Transmission leaks happen where there’s a gap in the transmission pan gasket and fluid has seeped into the system. This gap affects the oil passage tubes too which spills the oil.

The solution to this problem lies in the ATP AT-205. It is capable of stopping transmission leaks (both manual and automatic) by sealing the gaps and the passage tubes which are affected.

Stop Leaks In Power Steering: Power steering pumps can leak with time or when a head gasket gets damaged and can’t control the path of the fluids.

When power steering suffers a leak, it may lead to power steering rack damage which is a critical component, and the cost to fix a power steering rack may equal the car’s own worth. Thankfully, ATP AT-205 can stop leaks in the rack, pinion, and steering box.

Stops Leaks In The Hydraulic Systems: The pump shaft in the hydraulic system of a car may suffer a leaking problem which is dangerous. It is connected to the brake systems and may even lead to a brake failure.

Adding the ATP AT-205 in the hydraulic reservoir can seal leaks in the system and promote smooth braking operations. However, note that this sealer can’t be used on the brake system directly.

Non-Toxic And Compatible With Most Oils And Systems: The best thing about this sealer is that it doesn’t contain any harmful matter that may damage the engine or any other part. It is compatible with conventional oil, hydraulic oil, synthetic oil, gear oil, ATF, and power steering oils as well.

No Seal Breakdown: Unlike sealers that have petroleum distillate rubber conditioner that mushes seals and breaks them down, this sealer doesn’t do that. The ATP AT-205 isn’t a petroleum-based formula which is why it doesn’t damage the rubber seals.

Things We Liked:

  • Acts quickly.
  • Rejuvenates rubber seals.
  • Compatible with many oil types.
  • Contains no such solvents that may react with engine and cause damage.

Things We Didn’t Like:

  • Can’t be used on brakes.

Frequently Asked Questions About ATP AT-205

In how many engine types can this gasket sealer be used?

Lots of engines because it is designed to work with both diesel and petrol engines.

How much time does it take to show results?

It takes about 5 hours to completely seal leaks.

Is it harmful and does it require the service of an expert?

No. The substance is non-toxic and anyone can fill the engine with this sealer.

Will it work on motorcycle engine leaks?

If they contain a rubber gasket then yes it will.

ATP AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle
  • Professional strength fast acting resealer, stops leaks fast
  • Rejuivinates all rubber seals & gaskets in engines, transmissions, power steering, differentials and hydraulic systems
  • Compatible with conventional and synthetic oils, ATF, gear oil, power steering fluids and hydraulic oil
  • Does not contain petroleum distillates, will not over-swell or breakdown seals
  • 8oz bottle will treat a 6 quart capacity, adjust accordingly

Bar’s Leak HG-1 HEAD SEAL Blown Head Gasket Repair

This is a great engine block sealer because it doesn’t just repair blown gasket heads but also seals cracks in engine blocks and cylinders no matter where they are.

Bar’s Leak HG-1 HEAD SEAL Blown Head Gasket Sealer
Bar’s Leak HG-1 HEAD Gasket Sealer

This is one of the best gasket sealers because it is designed to eliminate overheating issues in vehicles that overheat in just 15 minutes. It does so by repairing the gasket head.

Works On Many Engines: Apart from working on all diesel and gasoline engines, it works on turbocharged and racing engines as well.

Permanent Stop On Leaks: This sealer is unique because it is made up of sodium silicate sealing liquid and antifreeze gasket sealing particles that contain carbon fibers.

This combination is a perfect fit to seal leaks as it penetrates deep to find gaps and cracks, and seals them with a very strong bond that won’t come off in the future.

Repairs Multiple Types Of Leaks: The sealer works on different types of leaks. Radiator leaks are difficult to seal because of the pressure which gathers inside, but it is not too much for his beauty as it can seal such leaks too.

Other than that, intake gasket repairs, gasket blown heads, heater core leaks, and plug leaks are also sealed by this sealer.

Removes Air Bubbles From The System: Severe problems begin to occur when leaks in the system begin to let air inside. It forms air bubbles in the cooling system which contribute to cooling loss and promotes overheating.

This formula works on such leaks and seals them for good and that’s not all, it also frees up the system from air bubbles.

Things We Liked:

  • Seals severe leaks quickly.
  • Eliminates severe overheating issues in vehicles.
  • Doesn’t clog heater cores.
  • Safe and easy to use.
  • A permanent fix for leaks.

Things We Didn’t Like:

  • Only to be used in the coolant system.

Common Questions of Bar’s Leak H1

In which kinds of vehicles can this sealer be used?

All those vehicles are water-cooled vehicles. These include cars, SUVs, vans, and trucks.

How much time does it take to show results?

It takes more than 3 hours because first, one needs to drain the cooling system of the coolant in it. Warm up your car and leave it idle to cool off. Once it does, pour the sealer and again leave it to cool off.

How much to add in the coolant system?

½ a bottle for 6 to 9 quarts capacity.

1 bottle for 10 to 20 quarts capacity.

Can it be added to the engine?

No. It is only to be added to the radiator and leave the engine running while doing so.

How To Use K-Seal?

The instructions are on the bottle. Just shake the bottle well before use. Make sure the engine is cold. Turn the heater and fan at a high temperature. Keep the engine running for the thermostat to open. Add the sealer and allow the car to cool.

Bar's Leak HG-1 HEAD SEAL Blown Head Gasket Repair
  • Repairs Blown Head And Intake Gasket Leaks
  • Seals Cracked Cylinder Heads And Blocks
  • Stops Heater Core And Radiator Leaks
  • Fixes Leaking Freeze And Core Plugs

K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair

This is one of the best stop-leak sealers because, unlike other sealers, K-seal can work by mixing with any kind of antifreeze.

K-Seal Permanent Coolant Leak Repair
K-Seal Permanent Coolant Leak Repair

Efficient And Produces Fast Results: Head gasket problems are problematic and time-consuming. It may take between 10 to 14 hours for a mechanic to dismantle the engine, find the leaks and cracks, and repair them manually.

On the other hand, K-seal is like that magic potion that makes its way into nook and crannies under just 3 minutes and repairs leaks and cracks like a charm. It’s hard to find such efficiency in a head gasket sealer.

Easy To Use: Many head gasket sealers instructions say to drain the coolant system first before adding it but K-Seal says otherwise.

You don’t have to drain away from the contents before using it. All you need to do is shake the bottle well before use, pour the contents in and let the sealer do its magic.

Permanent Leak Repair: The K-Seal ST5501 is manufactured using two of the strongest ingredients, namely copper and microfibers. Their combination offers a top-notch strong bond that acts as a permanent repair solution on leaks and seals.

Doesn’t Block Tubes Or Openings: The sealer is meant to work on holes and tiny cracks that measure up to 0.063mm. Since it works on smaller-sized cracks and leaks, there is little to no chance of blocking any openings or tubes in the engine.

Repairs Many Kinds Of Leaks: Unlike most sealers, this one doesn’t only repair cracks and leaks. It repairs a lot more than that.

It works upon warped and bad head gaskets, repairs water pump casing, heater cores without clogging them, freeze plugs, cylinder heads, and engine blocks too, thus it can be called the best engine block sealer.

When you have the K-Seal by your side, you can save a lot of money by cutting trips to the mechanics.

Can Be Used In Multiple Vehicles: It is a personal favorite of technicians and mechanics because it works well in the case of water-cooled engines including bikes, machinery, commercial vehicles, and cars.

Since the sealer meets ASTM standards, it is one of the most popular ones on the market.

Works Systematically On All Kinds Of Leaks: Some sealers find it difficult to seal gaps and build a permanent seal. K-Seal works in a smart way by first locating the leak or crack and then letting its microfibers rub between the gap to create a strong seal fiber by fiber to prevent leakage through the gap.

No Clogging: A lot of car enthusiasts complain about head gasket sealers clogging up the radiator and heater cores. This happens when the sealant’s matter gets stuck into the tubes, jamming them. However, the particles in K-Seal are very thoughtfully engineered to repair holes that are only 0.635mm in size. The benefit of letting them repair small holes only makes sure that no clogging takes place in the radiator or the heater core.

Seals Can Withstand High Pressure: The microfibers that seal the cracks, holes, and leaks get exposed to the gases present in the combustion chamber and the heat present in the cooling system.

Upon exposure with them, a strong seal is created on the spots that need repairing. The seal is so strong that it can withstand extreme pressures exerted by the combustion chamber.

In short, the seals of K-seal are permanent and they stay their ground even if there is excessive pressure in the system.

Things We Liked:

  • Antifreeze compatible.
  • No draining or flushing needed.
  • Simple to use. Just shake, pour and use.

Things We Didn’t Like:

  • Doesn’t repair holes larger than 0.0635mm in diameter.

K-Seals’s FAQ

Can I use it to repair big holes?

You can but it will not give you any results so there is no point in doing so.

How many bottles do I need if I have a 4-cylinder car?

In most cases, 1 bottle would be enough.

K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair , BLUE
  • Permanent Coolant Leak Repair - Just Shake, Pour And Go.Fit Type: Universal
  • Mixes With All Antifreeze
  • No Draining Or Flushing
  • Fixes Cracks And Leaks In Radiator, Head Gasket, Freeze Plugs, Cylinder Heads, Heater Core, Water Pump Casing And Engine Blocks

Bar’s Leaks 1111 Head Gasket Fix

This one is a strong solution that provides permanent seals on leaks, especially on head gaskets. Unlike other sealants, this can do its work without having to drain the system from previous sealants or coolants.

Bar's Leaks 1111 Head Gasket Fix
Bar’s Leaks 1111 Head Gasket Sealer

It is a combination of multiple gasket sealing matters, antifreeze, and sodium silicate liquid. All of the three ingredients are compatible with one another.

The solution functions by penetrating deep into the system and finding gaps and cracks to immediately take action against the leaks.

When the sealant goes inside the combustion chamber, its ingredients react with the chamber’s heat to make the seals even stronger. In fact, sometimes, the seals become even stronger than a gasket itself. The sealer works on both diesel and gasoline engines which are water-cooled.

You can use the formula in both aluminum and cast iron blocks. This makes it stand out amongst traditional products which only work on rubber materials. Thanks to this, the Bar’s Leaks 1111 can be used to repair cylinder heads, radiator heads, gasket heads, freeze plugs, gaps, cracks, leaks, and intake gaskets.

Make sure to read the instructions on the bottle before using the sealant. The instructions say that before using it, let your car’s engine cool down so that you can take off the radiator cap without any problems. Once done, shake the bottle well and then pour the mixture into the radiator.

The right way to use the product is to fill the radiator, close the cap. Turn the engine on and leave it idle for 20 minutes.

Things We Liked:

  • It works effectively on leaks, cracks, holes, and gaps.
  • Safe to use.
  • Works within a short time

Things We Didn’t Like:

  • Not suitable for older engines.

Bar’s Leak 111’s FAQ

Can it seal intake gaskets?

In most cases it does.

How much do you use?

A bottle is enough for 4, 6, and 7 cylinders vehicles.

Bar's Leaks Block Seal Head Gasket Fix
  • Stops block leaks
  • Seals cracked cylinder heads and blocks
  • Repairs blown head gaskets
  • Contains a combination of antifreeze compatible sodium silicate sealing liquid and various size gasket sealing particles which penetrate gaps & cracks and harden to permanently stop leaks.

Products That Are Popular But Not In Our List. Why?

There are two products which despite having good popularity aren’t a perfect fit to repair head gaskets. The BlueDevil Pour-N-Go Head Gasket Sealer and K&W FiberLock Head Gasket & Block Repair.

Let’s talk about why we don’t recommend The BlueDevil Pour And Go Head Gasket Sealer:

While the Blue Devil is a popular product but many users have shared their concerns regarding its use as the solution apparently begins to block passages and tubes with some kind of matter. This negatively affects the whole engine performance and may cause several problems in the car’s engine.

This may be due to the reaction that takes place between the solution and the chamber’s heat which creates solid particles that plug passages. The Blue Devil sure helps repair leaks and gaps but it may not be a suitable option in the long run.

Apart from that, some users also believe that the heater core started to trigger strange behavior after The Blue Devil was used in the car.

So, this is not recommended as it may damage the engine.

Why Not To Use K&W Fiberlock And Block Repair

Like The Blue Devil sealer, this one too is associated with clogging up the passages in the coolant system, especially the auxiliary coolers which are present in the coolant system.

Major damage caused by it is in diesel engines. Since such engines need to be completely drenched in the coolant, blockages in the passage can overheat the oil and destroy the motor completely.

However, it’s not that dangerous to use if you first flush out the radiator in the right manner. Drain the contents with a hose at least thrice before using the product.

How To Diagnose A Blown Head Gasket?

There are many signs that can help determine if the problems occurring in the car are due to a blown-up head gasket or not.

Decreases Engine Performance: Since a head gasket keeps the fluids from mixing into one another, the engine remains cool and so do other parts. However, in the case of a blown up head gasket, issues like overheating and compression take place. These affect the performance of the engine and a noticeable change is experienced.

Too Much Pressure: When the head gasket blows, too much pressure begins to accumulate in the radiator which often blows off the radiator cap or inflicts cracks on it. If you neglect it for long, it may blow up the radiator hose and the radiator tank as well.

Excessive Overheating: The most severe and concerning problem caused by a blown-up head gasket is the excessive overheating issue. The temperature may get so high that it ruptures the rings of the head gasket and the surrounding components as well. This causes several leaks and cracks in the radiator which is causing excessive overheating and frequent engine turn-offs.

External Oil Leaks: External leaks are common when a gasket head gets damaged. The reason is, it is the head gasket that ensures to seal the passages where oil and coolants run from, and upon damaging, their contents begin to spill.

A lot of drivers mistake these oil spills to come from valves or parts below the transmission system when they may very well be because of broken oil passage and a failed head gasket.

If your car is asking to be filled with too much coolant then there might be a leak. Try looking below the exhaust manifold for leakage.

It should be kept in mind that visual inspection is not an accurate method to figure out if there’s a leak or not due to a blown-up head gasket. If you do see leaks then move to other signs to confirm if the gasket is really at fault.

Spark Plugs May be Tinted: Tinted spark plugs also point at the possibility of a blown-up gasket. This happens because the coolant sprays out of the holes in the plugs and tints them. Notice what color tint is forming on the plug, if it’s the same as your coolant then most probably the head gasket is to blame.

Check If The Oil Is Contaminated: Inspect the cap on the top for the occurrence of milk-like substance. It forms when the coolant mixes with the engine oil when the gasket blows up.

The white emission of smoke coming from the exhaust is due to this problem as the oil gets contaminated.

How Long Does a Head Gasket Sealant Last?

There’s no doubt about the fact that head gasket sealers really work when it comes to repairing leaks, gaps, cracks, and holes in the gasket sealer.

In fact, many mechanics also use different sealers to solve problems related to head gaskets.

Remember that not all sealers are made with the same ingredients and have the same traits. So, you can’t expect two sealers to last for the same time.

Other than that, some sellers are effective immediately while some need time. For instance, the Bar’ Leak HG-1 is said to provide a permanent seal on leaks but a Blue Devil head solution may not.

Long story short, a sealer that provides permanent seals will last longer than the ones that do not.

The sealers that we included in our top 5 list provide permanent seals and as per customer reviews, they seem to last for years and its users are quite satisfied with the results.

The Verdict

All in all, head gasket sealers are no less than magic potions that seal off leaks permanently. However, make sure to choose one that suits your car’s engine because not all sealers may be compatible with your car.

Sealers need to be poured in carefully and with precaution. More importantly, the instructions given on the bottles need to be followed to avoid problems.

The right head gasket sealer can save you money, time, and offer you peace of mind, so choose wisely.

Last update on 2023-01-28 / Affiliate links / Images from Amazon Product Advertising API

Jack Harris

Jack Harris is a talented and advanced author, blogger, auto expert and senior technical consultant with Autosneed. He is a mechanical engineer who holds a Machine Lubricant Analyst (MLA) Level III certification and a Machine Lubrication Technician (MLT) Level II certification through the International Council for Machinery Lubrication (ICML) and ASE Certified. After years of working as both an automotive journalist and a Ford factory technician, to say I live and breathe the automotive world could still be considered an understatement.

9 thoughts on “Best Head Gasket Sealer Reviews”

  1. I’ve a question. Is it safe to use Bar’s Leaks block seal head gasket fix for a car that runs fine but has a blown head gasket that seems to be leaking coolant into the engine oil?

  2. I have been a mechanic since 1963.

    These products have been around since about that time also.

    I have never seen them work.

    Changing a head gasket is much easier to do to pre 1970 vehicles

    Newer cars get more complicated for each year after 1971, because of new emissions and fuel systems.


    Do NOT try to fix it yourself unless you have had Auto Mechanic courses and have done engine repairs under a master mechanics supervision. If you decide to try it yourself, set up 2. Video cameras or get a friend to video tape you taking the motor apart use Plasti. Food jars or shoe boxes to hold nuts, bolts, clamps, screws , hoses etc. Label each box about where they came from.

    Disassemble the top of the motor while being recorded. This is important so you can. Easily see where parts came from and how to reassemble them later.

    Head gasket replacement can be tricky. If the car is over 10 years old or has over 140,000 miles on it, it may not be worth fixing unless it’s otherwise I. Good shape. If it’s an automatic transmission, you can count on that trans failing just before or after the head gasket, which most trans shops will also try to rape you on the price. They were designed to fail after the vehicle goes over 120,000 miles. Check out prices on brand name rebuilt engines and transmissions. They are usually the best and least expensive way to go.

    If you drove the car after the head gasket leaked, you should take the head to a auto machine shop to check for warpage before you try to use it again. Otherwise it may blow atain as soon as you reassemble it

    A free bonus tip. If you get a leak in your radiator, while driving far from home, pull over. Let the engine cool down for at least an hour with the hood open.

    During that time cadrefully walk along the shoulder if the road, keeping an eye out for traffic while also looking for cigerret butts.

    Remove the filter and throw away . Crumble the butt up so the tobacco leaves can get out. Dump the leaves inside your open radiator cap and add fresh water mixed 50/50 with antifreeze. Run the engine until it reaches operating temp the tobacco leaves will find the leak and plug it shut. That’s a free fix that I’ve seen keep working for as long as 4 years, before it leaked again

    One last hint. Call your local county School superintendent and ask what schools have auto mechanic classes. Call those who do and see if that class will use your vehicle to teach the class how to repair a head gasket or if they have night adult classes where you may be taught better how to replace your own head gasket.

    I Wish You All The Best of Luck

    Most dealers will rape you on the price.

    Check out several local mechanics

  3. I used K&W head, It worked I took out the thermostat first though. just used this on my daughter’s car she didn’t know water cools the engine and ending up blowing the gasket this stuff was awesome 🙂


Leave a Comment