What Problems Can Head Gasket Sealant Fix?



Head gasket sealant can be a lifesaver when you have a leak and aren’t able to get the head gasket fixed right away. In addition to plugging holes in head gaskets, there are other problems head gasket sealant can fix.

Head gasket sealant can help with the following engine issues:

  • Cracked cylinder heads
  • Heater cores
  • Freeze plug

Head Gaskets Explained

The head gasket is a simple piece of automotive equipment that literally stands between your engine and catastrophe. A small leak in the head gasket can lead to a total engine overhaul costing thousands of dollars if left unchecked.

Why is that? Because the head gasket protects the combustion chamber of the engine that produces fire and fumes of fuel and little explosions from the mechanical parts of the engine that move up and down, back and forth, and require lubrication and coolant. The head gasket keeps the coolant and lubricating oil out of the combustion area and the high heat and pressure of combustion away from the moving parts. Any seepage across that barrier is a recipe for disaster.

Head gaskets are relatively simple and inexpensive automotive parts. Just a fraction of an inch thick and a few inches wide, the gasket is usually a single piece of steel, carbon or copper, or a composite that might include steel and an elastic compound. Head gaskets do not move, spark or conduct electricity; they simply wall off one section of the engine from another.

Most Common Problems Head Gasket Sealant Can Fix

You can pick up a head gasket itself for twenty bucks, but head gasket replacement can cost over $1000

Access to the head gasket requires much of the engine to be disassembled or removed, then reassembled once the new head gasket is installed. This is an extremely time-intensive process at $100 an hour or more. Once the engine is deconstructed, it makes sense to change out other parts as well. All that comes with a hefty price tag.

It is possible to avoid the cost of head gasket replacement with a $40-$80 can of head gasket sealer, available at any automotive store or online. The sealer is a liquid that is poured into the radiator and pumped through the engine that hunts out and fills cracks in metals and composites.

Because head gasket sealant travels throughout the engine seeking out cracks and leaks, it is like a Swiss army knife for automotive problems. High-quality sealant sniffs out leaks and cracks and bonds to a variety of surfaces for a permanent seal in parts other than head gaskets, such as warped or cracked cylinder heads, heater cores and freeze plugs.

Let’s take a look at the other problems head gasket sealant can fix.

Cracked Cylinder Heads

The cylinder head sits atop the chamber in which the piston moves up and down, turning the crankshaft, and ultimately, the wheels. Under extreme conditions, such as inside an automobile engine when it is running, cylinder heads can crack, causing many of the same issues as a blown head gasket. These include oil and coolant leaking or exiting through the exhaust pipe, overheating, rough idling, poor engine performance, and if left untreated, complete engine failure.

A new cylinder head is significantly more expensive than a head gasket – usually a couple hundred dollars – but the labor to replace it is much less involved. An average cylinder head replacement costs about $500, making head gasket sealant an inexpensive temporary alternative.

BlueDevil Head Gasket Sealer bonds to a variety of surfaces to plug gaps without particulates or solid matter and bonds to a variety of surfaces that might be used in cylinder heads. The sealer is compatible with gasoline and diesel engines and can withstand the extreme temperatures and temperature swings present in engines.

Holes in Heater Cores

Heater cores are usually made of aluminum and sit beneath the dash of the vehicle, serving as a miniature radiator in reverse, transferring heat from used coolant to the passenger compartment when the heater is turned on.

In other words, the heater core is responsible for keeping the humans inside the vehicle warm during cold weather.

Like every other component in an automobile, heater cores are exposed to extreme heat as 200-degree coolant flows through them, potentially causing cracking and warping. The cracks may start as small as a pinhead but they will often expand and prevent the heater core from working properly.

Indications that the heater core has stopped working include a cold interior, overuse of coolant, a fruity smell around the vehicle indicating that coolant is leaking, and windows fogging up on the inside.

A heater core can be purchased for less than $100 but labor charges can raise the cost of heater core replacement to $500-$1000. Again, head gasket sealant serves as a low-cost alternative by homing in on those microscopic holes and bonding with the aluminum, much the way windshield repair companies patch small windshield cracks with epoxy.

Damaged Freeze Plugs

Freeze plugs are cylindrical plugs that fill the passages in the engine block where the antifreeze and water mixture flows. This mix can eventually freeze, causing the mixture to expand with massive force and threatening to crack the engine block.

That is where the freeze plugs come in. They are designed to pop out when the block begins expanding, avoiding thousands of dollars of damage to your engine. Sometimes, the expansion is minor and the freeze plugs crack instead. That can cause antifreeze to leak and also prevent the plugs from doing their job of protecting the engine.

Head gasket sealant to the rescue!

BlueDevil Pour-N-Go Head Gasket Sealer uses a chemical that reacts to the temperature differential at the leak point to form a permanent bond.  BlueDevil is safe for the entire cooling system.

Freeze plugs themselves are a couple of bucks each, but their accessibility varies widely, and so does the cost to replace them. The labor is going to run anywhere from $300 to $1000, depending if the transmission must be lifted out. A sealant is a cost-effective solution.

The key to achieving a permanent seal from head gasket sealant is to use it properly. For BlueDevil Head Gasket Sealer, that means removing the thermostat while the engine is cold and flushing the cooling system with a flushing agent (such as BlueDevil Radiator Flush.) The system should be filled again with water, leaving enough room for a can of BluDevil Head Gasket Sealer to be poured in slowly. The vehicle should be allowed to idle with the radiator cap on for 50 minutes to allow the sealer to circulate through the engine and work its magic.

Consult an Automotive Professional

Sealant is a great backup plan that can often provide a solution while averting large engine repair bills. Taking care of the vehicle over the course of its life is always the best option, usually by allowing a licensed automotive professional to diagnose and service it. If trouble with your vehicle persists even after using sealant, be sure to take it to a licensed mechanic.

BlueDevil Products can be found at AutoZone, Advance Auto Parts, O’Reilly Auto Parts, NAPA, Parts Authority, and other major auto parts retailers.

25 responses to "What Problems Can Head Gasket Sealant Fix?"


  1. Joseph Harrington on February 5, 2021 at 5:53 pm

    I have used Blue Devil head gasket sealer with great results. Will keeping proper levels of antifreeze be substantial or should I add some head gasket sealer occasionally for maintenance purposes. Is there a blue devil small oil leak sealer that works well seeking out small oil leaks?

    • BlueDevil Pro on February 8, 2021 at 8:42 am


      The BlueDevil Head Gasket Sealer should not be used as a preventative measure. Once the product seals, it would be a permanent seal, so you should be good to go at this point. We do manufacture the BlueDevil Oil Stop Leak, which is intended to treat seeping or lightly dripping oil leaks.

      Thank you!


  2. Joseph Harrington on February 5, 2021 at 6:05 pm

    Is Blue Devil radiator flush best to use prior to using Blue Devil head gasket sealer… and is so, why?

    • BlueDevil Pro on February 8, 2021 at 8:44 am


      The reason you are flushing the cooling system prior to using the BlueDevil Head Gasket Sealer is to ensure the system is clean of any jellied antifreeze, debris, rust, etc or anything else that would potentially impede flow. A clean, free-flowing system, is what gives the Head Gasket Sealer the best chance at being successful.

      Thank you!


  3. Wendy McCall Johnson on February 5, 2021 at 11:26 pm

    My head gasket blew, I was broke and needed a cheaper fix than my mechanic quoted So, I went online & came across blue devils page and thought worse case, I’d waste $70, but, if it worked, I’d save a huge amount. This stuff is SIMPLY AMAZING! That was over a year ago, and she’s still running strong! I was a walking talking billboard for your product! Lol I’m fact 3 of my friends who also had issues tried Blue Devil sealant as well with similar results! Seriously was a blessing to see your web page.. I’d just lost hours at work, separated after 38ys of marriage, not a clue what I was going to do, then my trucks issues!! Extremely thankful and definitely a faithful customer for life ! To say Blue Devil products are MIRACULOUS is an understatement! Can’t thank you enough😊

    • BlueDevil Pro on February 8, 2021 at 9:30 am


      Thank you for sharing! We are happy to hear of the success you’ve had with the BlueDevil Head Gasket Sealer, and also happy to hear your friends had similar results! Once the product seals, it would be a permanent seal. You should be good to go at this point. Your feedback is very much appreciated.

      Thank you!


  4. Sabastian on June 20, 2021 at 8:16 pm

    Coolant in my VW Polo 2012 got emptied in about a month. There is no visible leaks. Please suggest me any product to resolve my problem and instructions to use it.
    Many Thanks.

    • BlueDevil Pro on June 21, 2021 at 8:45 am


      Thank you for asking about your VW Polo. Are you noticing any other symptoms, such as smoke/steam from the exhaust or an overheating problem? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!


      • Alicia on March 20, 2023 at 2:53 pm

        Blue Devil worked on my Dodge Caravan 2001. I’ve only driven the car a few times on short drives of 30 – 60 minutes after the initial BD repair without over heating. I am concerned that antifreeze leaks out of the radiator. So far as long as I refill it, it runs, no smoke no other indication other than smeller the antifreeze after driving. When I refill it there are air bubbles. What do you recommend.
        Thanks very much from a BlueDevil fan,

        • BlueDevil Pro on March 21, 2023 at 9:34 am


          How quickly are you losing antifreeze? Have you attempted to bleed/burp the cooling system? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

          Thank you!


  5. Hal Armes on September 1, 2021 at 2:15 pm

    Will Blue Devil seal a head gasket when there is some oil in the coolant, or will the oil prevent Blue Devil from sticking and thus fully sealing the leak???

    • BlueDevil Pro on September 1, 2021 at 4:46 pm


      The BlueDevil Head Gasket Sealer is only intended for water/coolant leaks. Unfortunately, none of our products would help stop oil from getting into the coolant. A hard part repair may be your best option.

      Thank you!


  6. George on March 6, 2022 at 10:15 am

    I have a 2016 Volvo that has a one piece thermostat and so it cannot be removed as the Blu Devil directions state. Any suggestions

    • BlueDevil Pro on March 7, 2022 at 9:02 am


      Thank you for asking about your Volvo. The best way to get around the thermostat housing is by taking the thermostat and modifying it so that the middle piece does not close; you may remove this piece or gut the middle of the thermostat. By doing so you will create a free flow and still be able to have the full housing installed. The thermostat should remain “open” while BlueDevil circulates through the system. Once the BlueDevil procedure is complete you will need to replace the thermostat.

      Thank you!


  7. E on April 8, 2022 at 8:38 pm

    When I turn my car on and put water in my cooling it shoots out what does that mean?

    • BlueDevil Pro on April 11, 2022 at 8:30 am


      Where is the water shooting out of, the reservoir? Is the engine overheating at all? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!


  8. J on January 23, 2023 at 7:24 pm

    Can you advise can the HEAD GASKET REPAIR AND SEALER FIX – HEATER CORES – FREEZE PLUGS WARPED / CRACKED be used without flushing the cooling system or changing the thermostat. Can I just pour it in the radiator? The mechanic said the head gasket is leaking.

    • BlueDevil Pro on January 24, 2023 at 8:30 am


      You are not required to remove the thermostat nor flush the cooling system when using the BlueDevil Pour-N-Go Head Gasket Repair. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  9. Steven on January 24, 2023 at 3:22 am

    I have a 2002 Honda CR-V with a suspected small leak in the steel thermostat bypass pipe. I can probably fix this, but with only one leg working right now after a fall off the ladder, freezing cold, no driveway, no garage, I’m not really in a position to take the top of the engine components including the intake manifolds to get to this buried pipe and too broke for a mechanic to do it. Will any of your products be adequate enough to seal-up a small hose or pipe leak? Also, there are no signs of a head gasket problem but at nearly 300 thousand, mostly highway miles. I am also curious to know if your head gasket sealer is appropriate to use as a preventative measure on a high mile car?

    • BlueDevil Pro on January 24, 2023 at 8:36 am


      Thank you for asking about your Honda CR-V. Unfortunately, none of our products we manufacture would be intended for a hose or pipe leak. Having the hose/pipe replaced would be your best option. The BlueDevil Head Gasket Sealer should not be used as a preventative measure/maintenance. It is specifically intended to treat water/coolant leaks. It would not be appropriate to use in a situation where the vehicle is not experiencing a leak.

      Thank you!


      • Brian on February 19, 2023 at 8:00 am

        Hi, I have used your product in the past with succus and have recommended it for years. I currently have an issue that is slightly different then my other situation. My 94 explorer head gasket began leaking and I was burning coolant through the cylinders. That leak was repaired for several years after with your product. I currently have a head gasket failure that is allowing combustion gas into my coolant, effectively the opposite direction. I’m concerned that a sealant may not work as well because of the direction of flow but should your product work just as well? I use his truck for work everyday and don’t have an option of rebuilding the top end right now.

        • BlueDevil Pro on February 20, 2023 at 9:07 am


          BlueDevil Head Gasket Sealer will still work if your vehicle is getting combustion/exhaust gases blowing into the cooling system and creating pressure. To give yourself the best overall chance of BlueDevil working successfully, in addition to the directions, you should remove the spark plug from the cylinder with the leak; this will be the spark plug from the cylinder with the low compression reading. If you are not sure which one that is, you may pull all of the spark plugs and will notice one will have a white-crystal-like substance on it and/or may look dirty; this is the plug you should pull. Leave that plug out for the 50 minute idle in order to relieve the pressure from building up and thus allowing the product to seal properly. Be sure to follow the guidelines for the proper amount to use based on the size of your cooling system.

          Thank you!


  10. Bobby Phillips on April 2, 2023 at 6:30 pm

    I have a warped head on a 1988 toyota pickup 4 cylinder, It overheats real quick but no water is getting into oil . What , if any sealant do you recommend. The pickup body is so bad it is not worth repairing the head. I was hoping to get by another year or so.

    • BlueDevil Pro on April 3, 2023 at 9:17 am


      In order to get the benefit of using the BlueDevil Head Gasket Sealer, the vehicle would need to be able to maintain idle for a full 50 minutes, without overheating or stalling out. If the engine is overheating too quickly, a hard part repair may be your best option.

      Thank you!


Leave a Reply

Related Articles

Search Blog


Blog Categories