Reviews

Best Head Gasket Sealers: Permanently Solve Coolant and Engine Oil Leak Problems

Permanently seal cracks and coolant leaks with our top picks for the best head gasket sealer.

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BY Noelle Talmon / LAST UPDATED ON May 10, 2021

Nobody wants to experience a blown head gasket. This type of malfunction can cause a lot of issues, including engine misfires and oil leaks. You can choose to replace the entire head gasket or you can use a head gasket sealer instead. It's a much cheaper alternative, and depending on the circumstances can do a great job of correcting the problem. There are numerous head gasket sealers available online and in stores, so it can be hard to choose the best one for your needs. Check out some of the top options in our buying guide below.

Best Overall
Steel Seal Blown Head Gasket Fix Repair Sealer  
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Summary
Summary

An easy-to-use product that works well with both diesel and petrol engines. It’s a multi-use sealant that solves problems associated with head gasket leaks, heater core, and freeze plugs.

Pros
Pros
  • Easy to work with
  • Helps eliminate overheating problems
  • Improves vehicle mileage
  • Reduces smoke emissions and oil consumption
  • Works well for old trucks that cannot hold water
  • Backed by a 100 percent money-back guarantee
Cons
Cons
  • Expensive
  • Will only work well if you flush the engine first
Best Overall
Steel Seal Blown Head Gasket Fix Repair Sealer  
Best Value
K-Seal ST5516 HD
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Summary
Summary

An affordable sealant known to solve common problems fast and blends easily with antifreeze. Can eradicate tapping or flushing and repair other problems such as freeze plugs, heater cores, warped gaskets, and cracked heads.

Pros
Pros
  • Permanent solution to coolant leak repairs 
  • Mixes well with all antifreeze
  • Doesn’t require engine flushing or draining
  • Fixes multiple problems 
  • Comes with a friendly price tag
Cons
Cons
  • Sealant might not work well if the head gasket has extensive damage
  • Discolors some brands of antifreeze
Best Value
K-Seal ST5516 HD
Honorable Mention
BlueDevil Head Gasket Sealer
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Summary
Summary

A head gasket sealer that is compliant with ASTM standards and permanently seals the blown head gasket on all types of engines. The sealer is safe and easy to use.

Pros
Pros
  • Sealant is a permanent solution that works well during any weather condition
  • Prevents coolant leaks
  • Prevents the loss of radiator fluids
  • Helps with resolving cold start rough idle
  • Manufactured by a reputable company
Cons
Cons
  • You may have problems with the thermostat after using the product
  • May block the cylinder tubes and passages
Honorable Mention
BlueDevil Head Gasket Sealer

Why Trust Us


All of our reviews are based on market research, expert input, or practical experience with most products we include. This way, we offer genuine, accurate guides to help you find the best picks.

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Benefits of Head Gasket Sealers

  • Fix leakages in blown head gaskets. A blown head gasket is a big problem especially when you are traveling. Most people would opt to have a professional look at the head gasket, and that would translate to wasting a couple of hours as the issue gets fixed. With a high-grade sealant, you could permanently stop the leakage and prevent your engine from misfiring. 
  • Save money. Head gasket sealers are not as expensive as having the head gasket completely replaced. A replacement would require you to buy the head gasket, and you would also have to pay the automotive mechanic that handles the task. A head gasket sealer is an inexpensive option that provides a permanent solution, just like the replacement.
  • Multi-purpose product. A good gasket head sealer will not only help solve issues related to the head gasket; some of these products can be used on other leaks that might affect the performance of your engine. A high-grade sealer can also help solve problems related to the heater core and bad freeze plugs.
  • Time-saving. Unlike completely replacing the head gasket, using a sealant is an easy process. You just pour the sealant into the radiator cap, and it flows through the entire system discovering the leaks. The process is fast, and the leaks will be sealed in under an hour. 

Top Brands

BlueDevil

BlueDevil is a company that manufactures professional grade sealants for the automotive industry. The company supplies its products to over 400 distributors located across North America, South Africa, Asia, Europe, and South America. BlueDevil started selling its products in 1997 and is currently headquartered in South Carolina. The company manufactures some of the best head gasket repair additives, and the BlueDevil Head Gasket Sealer is one of its popular products.

ATP

ATP Automotive is a renowned automotive products manufacturer that has been in existence since 1955. The company has a 2,000 square foot state-of-the-art facility in Chicago, where it makes top-of-the-line aftermarket replacement parts and car care products for automatic transmissions. Consider trying out the ATP AT-205 Re-seal, which only seals minor leakages in the head gasket. 

K-Seal

K-Seal is an international company that manufactures and distributes sealants around the world. The company prides itself in its ability to sell millions of sealant bottles every year. It’s currently based in New Jersey. The K-Seal Ultimate Head Gasket Repair is one of the cheap head gasket sealers manufactured and distributed by K-Seal company.

Steel Seal

Steel Seal is a sealant manufacturing company that focuses on making and selling head gasket sealers. The company has been in business since 1999 and has provided mechanical solutions to hundreds of thousands of mechanics and car owners. Steel Seal is headquartered in the United Kingdom. The Steel Seal Blown Head Gasket Fix Repair Sealer is one of its best head gasket sealants.

Permatex

Based in Solon, Ohio, Permatex produces a wide variety of automotive maintenance and repair products, including gasket makers, sealants, adhesives, cleaners, and lubricants. We recommend the Permatex High Tack Gasket Sealant.

Bar’s Leaks

Bar's Leaks products are formulated and manufactured near Detroit, Mich. The company has been helping car owners tackle repair leaks for more than 70 years. Check out the Bar's Leaks Block Seal Permanent Head Gasket Fix.

Best Head Gasket Sealer Pricing

  • Under $20: This price range includes head gasket sealers that come in small containers weighing under 16 ounces. The content of these containers can help you handle leakages associated with the head gasket effectively, though you might have to get a bigger container for larger engines.
  • $25-$50: If you are looking for a larger container that can fix a couple of leaks, then look into products in this price range. The containers typically have 32 ounces of fluid. That’s enough to handle six- and eight-cylinder engines.
  • $50 and up: In this price range, you will find premium products. These are sealers that can fix cracked head gaskets permanently and are from reputable brands. The quantity is also enough to deal with larger engines such as six-cylinder engines and more.

Key Features

Quantity

The quantity of the sealant is measured in ounces. The quantity ranges from 8 ounces to a couple of gallons. Buy a sealant that’s enough for your problem. For smaller engines, the 16-ounce container is enough to seal a blown head gasket and will allow you to get to your destination. It’s also a good idea to have a small container for emergencies.

Ease of Use

Dealing with a head gasket leakage is as easy as pouring the sealant into the radiator. However, other issues may arise, and you may need to have some technical knowledge of the sealing process. Ensure the product you choose is easy to use and comes with clear instructions on how to seal different leakages.

Other Considerations

  • Type of Engine. The main types of engines are diesel and gasoline engines. These engines might require different types of sealants. When buying a high-grade sealant for your head gasket, make sure you check on the advantages the product has for your engine type.
  • Action Time. After pouring the sealant, you cannot use your vehicle for a certain period of time. You, therefore, need to know how long you have to wait out for the sealant to settle down. Most take about an hour or more depending on the size of your car’s radiator capacity.
  • Functionality. There are products that are designed to solve different leakage problems in the engine. Though you might have a head gasket problem, you can find a sealant that can fix that and also perform many other tasks. Make sure you read the product description to understand what else the sealant can do.

Best Head Gasket Sealers Reviews & Recommendations 2021

Best Overall
Steel Seal Blown Head Gasket Fix Repair Sealer

The Steel Seal gasket sealer comes in two bottles that are enough for people with bigger engines such as eight-cylinder engines. The product comes with easy-to-follow instructions, though you need slight automotive knowledge to use it. This sealer is designed for solving different blown head gasket symptoms, which include white smoke, engine overheating, external leaks, and watery oil.


A unique feature about this sealant is that it’s designed to take care of leaks in older engines with just one application. Also, this sealing agent doesn’t have particles that can build up, block tubes, and lead to more issues in the engine. The fluid will work by bonding to breaches and cracks, even when exposed to high temperatures, and provides permanent sealing solutions. You can expect fast sealing action, and the sealer works well with both gasoline and diesel engines.


Though the sealer is effective, it’s quite expensive. There are cheaper options that offer almost similar qualities to what the product has. You will also have to flush the system before using this sealer. That’s an inconvenience if you don’t have a lot of time on your side or money to buy a new coolant. However, this sealer is a great choice for people with bigger engines, old trucks, and second-hand vehicles.

Best Value
K-Seal Coolant Leak Repair

The K-Seal Coolant Leak Repair is a “shake, pour, and go” head gasket sealer that comes with an affordable price tag. This product’s standout feature is the fact that it’s compatible with any antifreeze product, which eliminates the need to flush out the coolant system before application. It’s a multipurpose product and you can safely use the sealant to solve other leakage issues related to the heater core, engine block, water pump casing, and freeze plugs.


The formula used to make this product uses a type of nanotechnology, which involves microfibers that mesh to seal cracks and leakages. The product is available in a 16-ounce container that can treat up to 55 quarts. You can expect to see the effect of the sealant within minutes of application. The sealant is easy to use and does not need any special skills.


The sealant might be fast but will only work for minor leaks. If you are dealing with extensive damage, you may want to consider a different product. There have been cases of the sealant discoloring some brands of antifreeze products. This sealant is, however, a great choice for people looking for an effective, yet affordable sealer.

Easiest To Use
BlueDevil Head Gasket Sealer

The BlueDevil gasket sealer is an easy-to-use sealer that saves you money in repair bills for your car. It’s a professional-grade head gasket sealer that also solves leakage issues associated with the heater cores, freeze plugs, and other components associated with the coolant apart from the radiator core. As long as you follow the instructions provided, the sealer provides a permanent leakage repair solution. 


You can use this product on gas and diesel engines regardless of the number of cylinders. This sealant has the advantage of making strong bonds with a wide range of materials including cast iron, plastic, aluminum, alloy, and many other types of metals. It also works well on cracked or warped heads, and you do not have to worry about coolant loss or leaks. The product solves internal engine issues for increased mileage.


The main drawback of this product is that it may start to block tubes and passages with some solid matter after some time. This is probably due to the reaction of the sealant when it gets heated up in the chamber. The thermostat may also develop some issues after the sealant is used. You also have to use the sealant with a fresh coolant; otherwise, it won’t work as effectively.

 Most Versatile
Gasgacinch Gasket Sealer and Belt Dressing

This gasket sealer and belt dressing comes in both an eight-ounce and four-ounce can and is known for featuring an image of a young woman on it. It's flexible and makes assembling/disassembling the engine and transmission much easier. Excess Gasgacinch is easy to rub away and doesn't require any solvents. The sealer bonds to a variety of surfaces, including steel, aluminum, titanium, lead, magnesium, rubber, and copper.


One of the great features of this sealer is you can use it in a variety of environments (hot, cold, wet, dry, etc.). It is high heat-, gasoline-, and oil-resistant. After curing, the sealer is flexible, fatigue-resistant, and has a high-peel and high-shear strength. It's ideal for use in auto, motorcycle, and truck repairs and is popular among high-performance engine builders.


There are not many issues with this product. One downside is that it comes in a small container. Also, every time you use it, air penetrates and it can go bad quickly unless you use it up. There have also been some complaints about the applicator not being a brush.

 Honorable Mention
Permatex High Tack Gasket Sealant

This high-tack gasket sealant comes in a variety of sizes, including 4-ounce and 16-ounce cans as well as aerosol cans. It dries quickly, is highly tacky, and produces a non-brittle film. The product works in temperatures ranging from -65 degrees to 500 degrees Fahrenheit. It is resistant to gas, oil, antifreeze, propane, and more.


This is an inexpensive general-purpose gasket cement with a very long shelf life as long as you seal it properly after each use. The lid has a rod and brush mounted together, so it makes it easier to use. It's great for holding gaskets that are prone to sliding, such as upside-down covers like oil pans. It's also suited for water pumps, timing chain covers, and other applications that use a thin paper gasket.


However, it has a very strong smell. The product is also very messy, and the brush applicator is shorter than the depth of the can, so it can be hard to get the last bit of it out, especially after it's dried up a bit.

 Honorable Mention
Bar's Leaks Block Seal Permanent Head Gasket Fix

This permanent head gasket sealer stops leaks using an antifreeze-compatible sodium silicate sealing liquid and several gasket-sealing elements. The liquid technology is designed to repair damaged, leaking, and blown head gaskets. It also seals cracked cylinder heads and blocks.


This U.S.-based company has a great reputation, and its first head gasket leak repair patent dates back to 1950. Users report that this product works as described. It plugs the leaks on head gaskets and takes care of other minor issues. It's a professional-grade product and easy to use.


One drawback is that if your heater core has a partial blockage, this sealer may clog it up. It's also really thick and can be difficult to pour into the radiator. In addition, in many cases, it's just a temporary solution and not a permanent fix (despite its name).

Honorable Mention
K&W Maintenance Chemicals FiberLock Head Gasket & Block Repair

The K&W FiberLock Head Gasket & Block Repair repairs cooling system leaks using military-grade fibers, nanotechnology, and Cool-X conditioner. It provides a multi-level repair on cracks and crevices and lowers the operating temperature. It works in conjunction with plain water or antifreeze and fixes problems related to head gaskets, engine blocks, cooling systems, and cylinder heads.


The formula is designed with a high strength-to-weight ratio to provide superior protection. The nanoparticles are able to penetrate tiny flaws, while the conditioning element aids in heat transfer. Simply shake the bottle, pour the contents into the radiator, turn the heat on high, and idle the engine for 15 minutes. Users report that it's very effective as long as you follow the directions. You don't have to drain the existing coolant, and it works as advertised.

    

However, if you don't follow the directions to a T, it won't produce the results you need. And like rival brands, it's not a permanent solution and will last only a certain amount of time based on your particular repair needs.

Honorable Mention
CRC K&W Block Seal Permanent Metallic Block & Radiator Seal

The CRC K&W 401016 Block Seal Permanent Metallic Block & Radiator Seal repairs cracks in holes in cast iron and aluminum engine blocks, head gaskets, freeze plugs, radiators, and heater cores. It produces a permanent molecular seal with a steel-like composition. You can use this formula on both gasoline and water-cooled diesel engines.


Block Seal holds up under extreme pressure and temperatures produced by cooling systems and won't wash away. It features professional-grade elements to seal leaks. Users have reported that this product can restore power and stop vehicles from overheating. As long as you do a thorough radiator flush prior to adding the Block Seal, it works as advertised.


Unfortunately, similar to other head gasket sealers, it's not a permanent fix. Eventually, you will likely have to replace your head gasket. It may only work for a short period of time, depending on the severity of the problem.

Honorable Mention
Irontite All Weather Seal

Irontite All Weather Seal is an effective coolant additive and cleaner that's been around for 60 years. It stops leaks in head gaskets, radiators, cylinder heads, and engine blocks. Compatible with gas and diesel engines and aluminum and cast iron blocks, this pour-and-go formula works with your existing coolant, so it does not require you to flush it.


We like this product because it takes just minutes to work. It blends with coolants/antifreeze to repair existing leaks and stop future leaks from occurring. It uses microfibers to detect leaks and operates in both extremely hot or cold conditions. All Weather Seal will not clog heater cores and can be used with vehicles as well as stationary engines, construction and mining equipment, etc. Users report that it works as advertised, particularly on smaller leaks.  


Some users complain that this product may only slow some leaks instead of stopping them. It won't work with all head gasket issues, and it just provides a temporary fix.

Honorable Mention
Bar’s Leak HEAD SEAL Blown Head Gasket Repair

This is the second product from Bar's Leak on our list. The company's HEAD SEAL Blown Head Gasket Repair is designed to fix blown head and intake gasket leaks. This professional-grade product seals cracked cylinder heads and blocks, stops leaks in the heater core and radiator, and repairs leaking freeze and core plugs.


This formula is not quite as strong as Bar's Leaks Head Gasket Fix. However, users report that it effectively seals cracks as long as you follow the directions. It has the potential to eliminate head gasket issues, remove coolant odors, stop water vapor from dripping out of the exhaust pipe, and increase compression. Overall, it's worth the investment and will keep your car running a little while longer before you need to replace the head gaskets.


Like the other products on this list, it's a temporary fix. It doesn't repair all problems, and there have been complaints that it can clog the radiator and heater core.

Tips

  • Make sure the product works with your antifreeze. Some head gasket sealer brands are not compatible with certain types of antifreeze. Read the instructions, and make sure it's safe to use with the antifreeze in your vehicle.
  • You can either completely replace a blown head gasket or try to use a sealant to repair it. Sometimes a sealant will do the job, and sometimes you need to invest in a new head gasket. If the part is old and too damaged, a sealant will probably not correct the problem, so don’t waste your time and energy on a product that won’t likely work.
  • If you think your vehicle has a blown head gasket, stop driving it. The oil will mix with the coolant, which will cause your car or truck to overheat and misfire.

FAQs

Q. Are head gasket sealers safe for the engine?

Good-quality head gasket sealers are designed to work effectively without compromising the engine. Most sealants have been tested and known to work well with either diesel or petrol engines and with different materials such as plastic, aluminum, and cast iron.

Q. Are head gasket sealers better than complete gasket replacement?

This depends on the level of damage you are dealing with. Most head gasket sealers provide a permanent solution to minor leakages. They will, however, only offer a temporary solution to severe leaks, and eventually, you might need a complete gasket replacement.

Q. How long will the head gasket sealer last after application?

Different brands have different qualities and while some will last long, others will not. It also depends on the severity of the damage to your head gasket. Most sealants offer permanent solutions to minor leaks but can only last for a maximum of six months if the damage is severe.

Q. Will the sealant clog other holes in the system?

Sealants are designed to fill up small holes in the head gasket. Most, however, can also clog up leaks in the transmission, power steering, and hydraulic systems. If you are dealing with bigger holes that the sealer cannot handle, you should think about replacing the head gasket. 

Final Thoughts

The Steel Seal Blown Head Gasket Fix Repair Sealer is our top pick for the best overall permanent head gasket sealer. It works well on older and new vehicles and is suitable for cars, vans, SUVs, and trucks.

If your budget is a little tight and you still need a professional-grade sealer, check out the K-Seal ST5516 HD. It’s an affordable sealant that comes with most of the qualities you can find in more expensive brands.