Blown Head Gasket Sealer Repairs

K&W engine block sealerHi there!

I get TONS of emails each week about head gasket leaks and blown head gasket problems. I was getting worn out typing replies back to my visitors so I made a video about the issue.

In the video below, you should be able to determine IF you really do have a head gasket leak (50% of my visitors do not although they were told they did) and what symptoms you should expect to see if you really do have a blown head gasket.

If you are absolutely sure you do have an internal coolant leak and the headgasket is probably the culprit I have a simple and very inexpensive suggestion for you to try yourself before you fork over a ton of money to your mechanic.

The sealer I talked about in the video is K&W Engine Block Seal, and you can find it at any parts store. Either the older version in the hard metal can (which I have always used) or the newer version in the green plastic bottle. Both seem to work very well.

I personally do not recommend using the product as the can instructs. We have been using it this way for MANY years with great success, and it is much easier to use this way.

1. Drain out all coolant from the radiator
2. Mix the sealer in a bucket with tap water
3. Pour contents of the bucket in the radiator and top off with water
4. Drive the vehicle for 500 miles total, the sooner the better
5. After 500 miles drain out the sealer and install coolant/water

If the sealer works and finds the hole, the repair should be permanent.

Make sure to keep the engine and radiator from freezing, since there is no coolant to prevent boil over or freezing during the 500 miles.

Make comments below with your success…or failure using the product.

Please share this with your friends,
Austin Davis

Posted in: Head Gaskets

20 Comments on "Blown Head Gasket Sealer Repairs"

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  2. Shane says:

    I have a 2005 Explorer. I had the symptoms of a leaking head gasket, plus one overheating event. Thermostat housing, water pump and lower radiator hose have all been replaced. Then I started leaking out the coolant reservoir cap. Replaced that. Still leaked, had white smoke coming from the exhaust occasionally on start-up, rough start up, and a check engine light with a cylinder #4 misfire code. My oil looks good though. Now i’m in the middle of my 500 miles with the K&W. My water level held for the first 150miles. I’m starting to leak out the cap again. Thoughts?

    • Austin Davis says:

      Did you get a cooling system pressure test first? If not, I would get one now and rule out any external leaks which the sealer will not repair. I would have expected the sealer to have worked its magic already if you did/do have a headgasket leak. The symptoms you mentioned are common headgasket symptoms though. The pressure test should leak down if there is any leak at all either internal or external….so get that done and get back to me.

  3. John B says:

    Good Morning Austin!

    I was inquiring with some questions after reading several of your articles regarding the K&W Head Gasket repair (in a bottle). I own a 2002 Subaru Legacy w/ a naturally aspirated EJ25 (2.5L SOHC) & 199k miles on it. The car doesn’t have any white smoke out the tail pipe, nor have we seen any overheating in the months since we bought it used. It DOES however have the classic driver side ‘external’ coolant leak from the head due to the poor gasket design these boxer engines are known for. No oil in coolant nor coolant in oil. We are a struggling family of 3 and cannot afford a new car nor the thousands for the HG repair.

    I have been reading of those who have used these products (mostly Bars, etc.) and most report of clogging, which you state isn’t something you have come across with the K&W following YOUR instructions.

    My questions:

    1. Considering how low the Subaru 2.5 boxer sits in the car, and the aluminum components of these engines – would the K&W be a suitable solution for our circumstance?

    2. Have you (or your garage) ever used the K&W HG Repair on a Subaru 2.5L Boxer engine? Did you find the results to be the same?

    I hope to ultimately build up some money, buy a used engine, freshen that up and replace. Living in a Snow Belt in the NE, the AWD is critical and we hope to keep the car on the road for as long as we can, as it’s our only car! Your experience and input regarding the known Subaru HG issues would be greatly appreciated!

    Best Regards,
    John B

    P.S. – THANK YOU for being a consumer advocate and not some of those artificially inflated product reviewer! The REAL WORLD situations are what people need these days!

    • Austin Davis says:

      Hello John, thanks for the kind words.

      First, I RARELY see any Subaru’s in our shop…or on the roads here in Houston, just not a very popular vehicle. We all drive big trucks pulling trailers full of horses and cattle. ha 🙂

      Now, will the product work on your vehicle….I think it should. Now, will it work on an external leak like you say you have, maybe…maybe not. The product needs to get hot enough to melt, and is mainly used for internal coolant leaks in the combustion chamber.

      Have I seen any clogging issues using the product, yes once, on a vehicle that had a stopped up radiator and the customer refused to replace it prior to adding the product. Did it do any other damage, no it did not but since the radiator was clogged to begin it just made THAT clog worse so no coolant would circulate.

      Will it cause any clogging if the radiator is clean, I have not seen that issue in my shop so I would say no.

      Should you try it on this particular case? Don’t see why not, what other alternative is there except to remove the cylinder head and do a valve job, resurface and gasket replacement assuming the block is not warped.

      I would still get a cooling system pressure test first, just to make sure there is not a leak up higher and running down the engine making it look like the headgasket is leaking…seen it many times before.

      I have heard of many complaints on Subaru headgaskets, so I would contact the dealer and make sure there is not a recall or a service bulletin available before you add the sealer and possibly void that warranty repair.

      If no warranty, or recall try the sealer..and keep us posted.


  4. Paul C. says:

    Hi Austin,

    I used the Blue Devil Brand Pour-N-GO Head gasket Sealant on my 2001 Chevy Venture as did not want to deal with the need to drain the radiator coolant first. Since then (about 400+ miles later), this has held up so far so appears to work well though the Blue Devil sealant costs slightly more than the K&W brand sealant.

    • Austin Davis says:

      Awesome Paul, what ever works is fine with me. I have not experimented much with Blue Devil products, thanks for sharing your experience. Guess I need to try it out myself.

  5. vira says:

    Hello again,
    i truly appreciate all the help you have attempted to give me with my jeep dilemma. Unfortunately, it’s not going too well. The sealer was put into the jeep per your specifications but it doesn’t seem to work. Each time it’s driven, water seeps into the oil and of course we can’t drive it or it will ruin the engine. So have to change the oil and that defeats the purpose of trying to save money. so I have to assume that we have cracked engine/head gasket?

    • Austin Davis says:

      If you have just a small amount of water getting into the oil….I THINK I would take my chances and drive it until the sealer has had time to find and repair the hole ( I would need to see it to be sure) . The sealer can take 30-50 miles of driving to take effect.

      If you just are looking at the oil filler lid and see milky oil residue then you are probably ok, since the 5 quarts of oil will be at the bottom of the engine mostly. Slightly remove the oil drain plug and see what comes out the bottom of the engine, light transparent brown oil is OK or a lot of milkshake looking oil is not? Oil is CHEAP compared to a valve job/headgasket replacement.

      If you have a LOT OF water getting into the oil, then ok…pull off the head, send to a machine shop and have them do a complete valve job, resurface and inspect the head, then install a new headgasket.

  6. vira says:

    Hello Austin,
    thank you for the quick reply. I think i am confused. 🙁 wouldn’t the water that is found in the oil be coming from the cracked engine/head gasket problem?? Isn’t that why we need to use the sealer to repair that specific leak? I think i misinformed you on the comment here, dated yesterday, when i said that oil was leaking up on the engine. it was not, sorry.I misunderstood my spouse, no oil was spewing out of the engine. what was found was water in the oil. I think we were under the assumption that the K&W would repair the crack in the engine block or the headgasket right away or within the 500 miles. WE have not driven it 500 miles yet but each time we drive it around, we have end up changing the oil because water seeps in there and we know it cannot be driven that way. Is that how your method works with the sealer? we need to be changing oil out every time we drive and filling the radiator with water. we have done research and the top reasons why water leaks into oil is because of a cracked engine/head gasket problem. WE checked for leaks again and we see non visibly. we must be doing something wrong, i am thinking.

    • Austin Davis says:

      OK, that does clarify things a bit, was thinking you had an external oil leak which the sealer will not repair. I think I would possibly start over again. Use 1 full can of the K&W engine block sealer additive and then drive the vehicle say 50 miles instantly to give the sealer time to find and repair the leak, then continue over time to accumulate the 500 miles in total. Grab a sandwich and a few gallons of water just in case and hit the road for 50 miles.

      If the sealer still does not work, then you will probably need to remove the cylinder head, do a valve job, resurface the cylinder head and replace the headgasket.

  7. vira says:

    Also, regarding the sealer, it’s the entire bottle and not half? correct? if so why would one need the entire bottle, won’t half work?

    • Austin Davis says:

      Yes, one full bottle is what is needed and recommended to make sure there is enough copper flake to repair the hole. Left in system and driven for 500 miles then drained out.

  8. vira says:

    Hello Austin,
    This is a follow up to the question i left on July 14 regarding the 99 Jeep Cherokee sport. We went ahead and used the sealer as you recommend. The jeep drove fine to work 10 miles each way. it did overheat a bit. a tuneup was done today. Thinking the jeep was fine, we drove it again when out of nowhere, oil starting spewing out from under the hood. and we noticed the temp gauge went up high then dropped again. And we noticed water in the oil, again. Ahh, we are at our wits end!! As explained in previous post, we put new radiator, thermostat, radiator cap, an oil change and tuneup. still no smoke coming out of tailpipe. we are convinced that it’s perhaps a cracked head or engine? don’t know what to think now. and yes we bled the system the first time around. Your thoughts?

    • Austin Davis says:

      You will need to see where the oil is coming from and repair that issue. You still have the sealer in the system and have driven 500 miles like I talked about? If there is a crack in the engine block or the headgasket the sealer should repair it. An external oil leak, the sealer will NOT repair that, so have that problem looked at with a mechanic and repaired.

  9. vira says:

    Hello Austin,
    Ok so let me make this short and sweet. Our 99 jeep overheated, and well the coolant spilled all over the place. Radiator was damaged so it along with the thermostat and radiator cap were replaced. The jeep is still over heating. No visible leaks were seen but coolant was being lost. We did a cooling system pressure test but not leak was seen although we know there is a leak. No white smoke is coming out of tailpipe, oil is fine but he jeep does struggle a bit. it overheats whether going slow or fast. So would this be a sign of a head gasket problem and should we proceed with using the sealer use it as you recommend? And i assume we use the whole bottle? hope that made sense and hope you can help!


    • Austin Davis says:

      Great question. Im going to just think out loud here for a minute. Engine overheats, radiator and thermostat were replaced, but engine still overheating at all speeds. Does the electric cooling fan at the radiator come on (does this model year have one or the standard pulley driven fan blade and clutch) is there enough air blowing across the radiator, can you feel the upper and lower radiator hoses when engine is running hot, they should be about the same temperature.

      If radiator hoses are not same temp, you have air bubbles in the system or a restriction somewhere…like a kink in radiator hose, waterpump not working/impeller rusted off (very rare but have seen it) or a faulty thermostat or improper thermostat installation or just wrong thermostat installed.

      If the radiator hoses are NOT the same temperature, then I would try to bleed out any air bubbles that might be in the system. (with engine cold, remove radiator cap and run engine and allow coolant to burp out…then SLOWLY refill it until engine is warm and coolant wants to constantly run out) if you still have problems then I would try another thermostat.

      I am not convinced you have a headgasket problem from what you have shared with me, but if you are really at your last straw and ruled out everything else then yes go ahead and try 1 can per my instructions on this page. I would also rule out the possibility of a gauge or temperature sending unit problem giving a false reading of overheating. Installing a temperature sending UNIT (not sensor) might be a good guess if you think this is a gauge problem.

      Keep me posted.

  10. Dave says:

    I have a 97 Jeep Cherokee that is my deer lease vehicle. I have all the symptoms of a blown head gasket. I want to try the K&W per your instructions of running it for 500 miles. The problem is that I don’t drive it more than 50-60 miles at most when I go there once a month. It will take me a while to rack up 500 miles and I worry that it will settle and clog up things it’s not supposed to clog up. What suggestions do you have?

    • Austin Davis says:

      Hi Dave,

      Well I have personally not left the product in a customer vehicle longer than a few weeks, but don’t think that letting it sit there will clog anything up. The copper flakes in the product have to melt, and until they do they are just flakes. Yes, they can clog up a radiator but usually if that happens a clogged up radiator was the initial problem to begin with, and should be replaced or the overheating and headgasket issue will return.

      I would make sure the radiator is not restricted (not that easy to look inside your radiator, so if you have more than 100,000 miles you might just replace it as insurance) and there are no external coolant leaks, then add the product per my instructions, grab a sandwich and a few gallons of water and take a road trip for 100 miles or so.

      In most cases, the product will take hold and permanently repair the gasket within that amount of travel, I say 500 miles to my customers just to be on the safe side of things. IF the white smoke, and coolant loss has stopped, then you can drain out the product. DO NOT drive if the engine is overheating though, you can make things worse. Remember the product should be used AFTER you have repaired the source of the overheating, the gasket failure is the symptom.

      Hope that helps, like the page on Facebook or social media if it has helped you….might help the next guy.


      Keep us updated if you can

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