Best Head Gasket Sealer for Reliable & Durable Results

A blown gasket can lead to numerous problems for car owners, like an oil leak or your engine misfiring. Since replacing the entire thing is expensive, you need the cheap and reliable alternative of the best head gasket sealer. However, the market is flooded with plenty of options that can make it challenging to select an ideal one. Luckily, we have dependable recommendations along with tips to ease your selection process discussed below.

What's the best head gasket sealant to use?

What Is a Head Gasket Sealer?

A head gasket is a vital part of the engine placed between the block and the cylinder head to ensure the combustion process is sealed within the mechanism. Additionally, this component separates the coolant from oil, ensuring they do not mix while they flow inside the engine. Plus, it should have a high-temperature tolerance so that it does not fail.

Blown head gaskets cause white smoke in the exhaust due to coolant leaks, oil contamination, loss of power to the engine, external leaks and overheating. You need a product that can seep into the cracks and harden and keep your vehicle running to solve these issues. A head gasket sealer, typically made of solid or particulate matter, can effectively plug leaks in the cylinder block.

5 Best Head Gasket Sealers

1. J-B Weld 31319 RTV Silicone Sealant and Adhesive

J-B Weld 31319 RTV Silicone Sealant and Adhesive - Black - 3 oz.
  • RTV Silicone sealant & adhesive : Is a general purpose RTV (Room...
  • Count on us : For more than 40 years, our products have earned a...
  • Easy to use : Upon curing, the silicone forms a tough, waterproof...
  • Versatile & dependable : Ideal for bonding, sealing, weather...

The J-B Weld 31319 RTV Silicone Sealant and Adhesive is a multipurpose head gasket sealer and one of the best products in its category. The room temperature vulcanized silicone can effectively seal and bond uneven surfaces. Plus, it is easy to use since you pour it out and onto the leaking area or use the included tool to ensure you can be precise.

Moreover, once cured, the head gasket sealer will form a durable and waterproof seal with numerous surfaces. So whether you are taking on a DIY project or trying to repair and restore household appliances or automotive accessories, you can be sure the product will not crack or weather.


  • The seal created is waterproof and rugged.
  • It is not susceptible to cracking or weathering.
  • You can use it for numerous applications around the home and in the car.
  • It is affordable.
  • It does not affect sensors.
  • It does not shrink while curing.


  • It takes an hour to set and 23 more for curing.
  • It may produce toxic chemicals when used during the first few times.
  • Extreme heat may cause it to lose its integrity and fail.

2. BlueDevil Head Gasket Sealer 38386

BlueDevil Head Gasket Sealer (38386)
  • Good for Head Gaskets, Warped or Cracked Heads, Heater Cores, and...
  • Contains no solid or particulate matter that can harm a vehicles...
  • Alternative solution for costly and time consuming repairs
  • Safe and easy to use
  • Permanent Repair

The BlueDevil Head Gasket Sealer is a quick and dependable fix for a cooling system in diesel and gasoline engines. Also, this product is widely compatible with different materials like plastic, numerous types of metals and alloys. So, if you are dealing with leaks in the freezer plugs or heater cores, this permanent head gasket sealer will not let you down as long as you follow the instructions carefully.

Suppose you do not want to spend a fortune and still get professional results. In that case, the BlueDevil Head Gasket Sealer is reliable regardless of how many cylinders are on your engine block. In addition, the lack of harmful chemicals and their resistance to extreme heat ensures that you see gains in your mileage after fixing the head gasket issue. However, you should not use this product on your radiator core.


  • You can fix materials like steel, cast iron, alloys and plastic.
  • It can deal with cracked, leaking or warped heads.
  • It offers professional results at an affordable price.
  • It is a quick fix regardless of the weather.
  • It will keep the radiator fluids from leaking.
  • It deals with cold starts rough idle.
  • It lasts long.
  • No overheating issues.
  • It is ideal for gasoline and diesel engines.
  • The BlueDevil Gasket Sealer does not contain harmful chemicals.


  • Heat in the cylinder heads causes it to form deposits that build up in the engine.
  • Your thermostat may be affected.
  • You need a fresh coolant along with this product. 

3. Bar's Leaks 1111 Block Seal Permanent Head Gasket Fix

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...

When it comes to a quick fix for cracked heads and seal leaks, the Bar's Leaks 111 Block Seal Permanent Head Gasket Fix is one of the most reliable options on the market. With a quick set and curing time of about 15 minutes, you are guaranteed a fast and permanent solution when dealing with a blown head gasket. Plus, the sodium silicate sealing liquid will penetrate and harden in cracked engine blocks and cylinder heads.

Depending on the size of the coolant system you want to seal, you need to follow the guidelines for the amount of product you use. Luckily, this head gasket sealer comes at an affordable price, making it the most reliable choice if you want to save more on repairs. Thus, this product is a lifesaver whenever you are in a pinch.


  • It cures in about 15 minutes.
  • It fills cracks in cylinder heads effectively.
  • It is not expensive.


  • Instructions are essential to get the best fix.
  • The thermostat may not perform well with this product.
  • You may see a powder left behind after use.

4. K-Seal ST5516 HD Multi-Purpose One Step Permanent Coolant Leak Repair

K-Seal ST5516 HD Multi Purpose One Step Permanent Coolant Leak Repair
  • Permanent coolant leak repair - Just shake, pour and go
  • Mixes with all antifreeze
  • No draining or flushing
  • Fixes cracks and leaks in radiator, head gasket, freeze plugs,...
  • If product did not seal head gasket leak, the system might be...

The K-Seal ST5516 Multi-Purpose Permanent Coolant Leak Repair is an easy to use and pretty affordable solution to leaks in freeze plugs, the heater core, the casing for the water pump and the engine block. Additionally, you do not need to go the extra mile of flushing out your cooling system since this head gasket sealant works with any brand of antifreeze. So, if you deal with minorly cracked cylinder heads and want fast and reliable results, this is the product for you.

When fixing issues like heater core leaks, the nanotechnology used in the manufacturing process of the gasket sealer comes in handy. For starters, the microfibers cling together to form a mesh that hardens within a few minutes after use. Plus, these tiny threads effectively seal cracks. Finally, getting the 16-ounce bottle means you can mix with up to a 55-quart capacity coolant system.


  • It creates a permanent seal when fixing radiators, cylinder heads, heater cores, engine blocks and freeze plugs.
  • Suitable for engines on SUVs, small trucks and cars.
  • It is affordable.
  • You can mix this sealer with any antifreeze with no adverse effects.
  • You do not need to drain or flush the cooling systems.
  • It is easy to use.
  • Cures within minutes.


  • It does not work on some engine models.
  • You need to follow the instructions intently to get the best results.
  • Some discoloration may occur, depending on the brand of antifreeze you use.

5. Bar's Leaks HG-1 Head Seal Blown Head Gasket Repair

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

Suppose you want to extend your vehicle's runtime before you need to replace the head gaskets; the professional-grade Head Seal Blown Head Gasket Repair is a safe bet. This product is dedicated to effectively fixing leaks in the radiator, core plugs, heater cores, and cracked heads and blocks. Although this variation is not as long-lasting as the other Bar's Leaks one on our list, it offers a reliable solution as long as you follow the instructions.

For sealing intake gaskets, preventing vapor from coming out the exhaust pipe and resolving issues with the coolant smelling, this blown head gasket fix will get the job done well. Its 2-in-1 formula features liquid ceramic penetrating cracks to form a hard seal and fibers that boost strength. Hence, 45 minutes after using it on plastic, aluminum, copper or cast iron, you are guaranteed a professional finish.


  • Stops leaks in heater cores, freeze plugs and radiators.
  • It works well to seal blown head gaskets and cracked engine blocks.
  • You do not need to flush the engine since it is compatible with antifreeze products.
  • It takes about 45 minutes to set.
  • Highly heat resistant.


  • It may clog the heater core and radiator.
  • It is not a permanent fix.
  • You cannot deviate from the instructions if you want to solve head gasket leak issues.

Things to Consider When Buying Head Gasket Sealers

a). Is it Durable?

Most head gasket sealers last quite a long time. However, the nature and extent of the damage should guide you on how long the repair will hold. Still, these products are not a permanent solution for leaks, and a head gasket replacement may eventually be necessary, primarily if you use the vehicle often.

Ideally, it would help if you look for a head gasket sealer with a reliable formula that will significantly extend the runtime of your engine. In addition, since it is challenging to compare the makeup of these products without using them, user reviews can help figure out the longevity of the options. After all, replacing head gaskets is expensive. Thus, it would be best if you bought as much time as possible.

b). Is it Simple to Use?

Some head gasket repair products offer a simple application procedure that involves removing the radiator cap, shaking the container, then pouring and finally adding antifreeze. On the other hand, some options require more work and knowledge of their functionality to get the best results. In these situations, a radiator flush may be necessary to fix gasket leaks.

Similarly, some head gasket problems require following special instructions to fix them. Additionally, it may be necessary to remove the thermostat then reinstall it afterward. Consequently, it helps to figure out if you can handle the head gasket fix repair yourself or get a professional depending on the sealer you buy.

c). Compatibility

Fortunately, most sealers work with numerous types of four-wheeled vehicles. Plus, some manufacturers create versatile ones that can also repair head gasket issues in motorbikes as well. Thus, take your time to find the right one.

Gas and diesel engines do not rely on the same components or way of function, so you need to consider these differences before buying a product to fix head gasket leaks. Additionally, six-cylinder engines may require specialized sealers. Hence, be careful when purchasing a sealant to ensure it will work for your specific case.

The brand of antifreeze you use also determines whether the head gasket sealer you buy will work well. Although some options are universally compatible with most antifreeze products, you need to be sure. After all, you can find one that requires a separate purchase of new and specific antifreeze fluids for your vehicle.

Frequently Asked Questions (FAQs) on Head Gasket Sealers

1. Do head gasket sealants work?

Head gasket sealers have specific formulations that can alleviate engine overheating issues. When you see symptoms like white smoke, there is likely leakage in your head gaskets that cause the oil and coolant to mix while the engine is running. Fortunately, the chemicals in sealants can fill the cracks, and they harden to form permanent plugs during the combustion process.

2. How long does a head gasket sealer last?

Different brands promise different periods depending on the quality of the products. Typically, considering the damage to the head gaskets, you can expect most products to offer at least six months of reliability. But, of course, buying more time hinges on the type of sealer you buy and how often you use your car.

3. What is the best sealer for a blown head gasket?

The J-B Weld 31319 RTV Silicone Sealant and Adhesive is the best solution for a blown head gasket since it is easy to use and versatile. After applying it, this product will take an hour to set and 24 hours to cure fully. However, the resultant seal is waterproof, resistant to weathering and will not crack or shrink. Consequently, you can rely on this sealant for heavy-duty repairs since it offers unmatched strength.