I Used K&W Block Sealer to Fix My Headgasket Leak

head-gasket-leaks.jpgHi Austin,

My son has a Honda Accord Coupe which had/has a leaking water pump that resulted in a definite blown head gasket. looked at your site and tried the K&W. Did everything according to the directions and the white smoke has dramatically dissipated but still a little bit of smoke and some small drops of water out of the tailpipe.

Also, it kept it’s temp but then would spike so we let it cool down, then added more water. Wanted to do the 500 miles but afraid of overheating so I drained the K&W and allowed it to dry for 2 days.

Today’s the day. I’m going to flush the K&W and fill her up with water at first to see if the stuff worked and then go for it. The question I have is this, if there’s still white smoke coming out and drips out of the tailpipe, would you think it’s best to retry the K&W?
You’re quick response is much appreciated and your site is fantastic pal.


Thanks for your email.

My concern here is you said the temperature spiked and you then had to add water.  Why did this happen?  Do you still have a coolant leak somewhere, internal or external like a hose?

I would get a cooling system pressure test FIRST, rule out a leak. Then I would look at the temperature spike issue next. Do you have a restriction in the radiator not allowing the coolant to circulate through the engine? A 20 year old radiator….I would expect it to be restricted at the bottom and  need to be replaced.

Does the electric cooling fan come on and off when at idle as the engine warms up? It should, so make sure it is.

IF you still have some white smoke, which could be just normal condensation left inside exhaust system that needs to be blown out. You can try the sealer again and drive 500 miles like I suggest.

It does work, so don’t give up hope but I have a feeling you have other issues that need to be fixed first.

Keep me posted, thanks for your comment.

Repeating MY recommendations for using K&W Block Sealer

1. Drain out all coolant/antifreeze from the system you can

2. Fill a bucket with tap water and 1 can of K&W Block Sealer

3. Stir bucket and add to radiator slowly, then top off with water

4. Then drive the car as you normally would a total of 500 miles, doesn’t have to be all at once.

5. Drain out the sealer and refill the system with 50/50 coolant/water mix

I DO NOT remove the thermostat, I DO NOT remove the spark plugs as the can suggests. I have done this many many times with great results. If you want to follow their instruction, great, it won’t hurt it will just involve more work on your part…but might be worth it if you have a large leak.

WARNING, The only real draw back to following MY instructions is without any antifreeze/coolant in the system the engine is more suspect to overheating or damage from freezing. Just use good judgement on freezing days and keep your eye on the temperature gauge on hot days.

Please share this with your friends,
Austin Davis

Posted in: Head Gaskets

47 Comments on "I Used K&W Block Sealer to Fix My Headgasket Leak"

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  1. chris jackson says:

    Austin I have a 1994 jeep wrangler it is leaking right above the exhaust manifold would that be a blown head gaskit and would K&w be an option for repair

    • Austin Davis says:

      Sorry for my delay Chris, had a family emergency that consumed my time. Does it leak coolant? The sealer will only work on internal coolant leaks, like from a head gasket or internal crack in the cooling system. So I would guess, it is not going to help your situation.??

  2. Umid says:

    Hi, can I use a similar product from a different manufacturer? I found one here in Canadian Tire called Rislone Head Gasket Fix: http://www.canadiantire.ca/en/pdp/rislone-head-gasket-fix-0380847p.html. Or does it have to be K&W Block Sealer? I just can’t find K&W Block Sealer other than online.

    Your opinion is appreciated.

    • Austin Davis says:

      I can only suggest/recommend what I have been using for 20+ years, you can order online from Amazon and have it shipped to you.

  3. Cantrell says:

    Hey austin i have a 1998 volvo s70 glt turbo with oil mixed with water is that,a,blown head gasket and do the K&W block seal work for that what do u think

    • Austin Davis says:

      definitely worth trying, but get a cooling system pressure test first to make sure there is an internal leak happening. Could be an intake manifold gasket that is leaking oil, and the sealer will not repair that.

  4. Marc. Smith says:

    Does the coolant reservoir have to be completely empty of coolant before adding k&w sealer in the radiator cap?

  5. jed says:

    Thanks Austin – One more ques.. My 2001 VW Beetle has a 1.8L Turbo. Is the K&W safe to use on Turbo engines?

    • Austin Davis says:

      Jed, I just called and talked with CRC Industries who makes K&W Block Sealer and they said it was safe to use on turbo engines.

    • James says:

      Does the sealant have to be applied with water mixed and if it wasn’t can it still be added? Does the car hqave to be driven 500 miles immediately after K&W is added or just a total of 500 miles? What could make the car run hot after K&W was applied?

  6. jed says:

    Hello – I have a 2001 VW Beetle. After I drain out all coolant from the radiator can I mix the sealer in a bucket and pour it into the reservoir tank? Or do I have to pour it into the radiator through the hose?

  7. John says:

    I use my vehicle to tow my boat. Can I safely tow my boat during the 500 mile peroid? It’s a 93 Grand Cherokee with a 4.0 straight six, and definitely has a cracked head gasket.

  8. John B says:

    So you say drive for 500 miles on just sealer and water? I think I’d have to refill water every other day? Does that sound plausible?


    • Austin Davis says:

      Usually the sealer will stop the INTERNAL leak within a few minutes of driving. If you have an EXTERNAL Leak, the sealer will not do anything for that and you will need to replace those leaking parts..ie. water pump, radiator etc. So yes, drive for 500 miles if you can for the best chance at a permanent repair to a blown head gasket or other INTERNAL coolant leak.

  9. andrew says:

    So I boutlght a demolition derby car with a blown head gasket, got a can on k and w and drained the radiator , did the mix in a jug and shaked it up , poured in slowly, then topped off the resivour with a bit of water ran the car for a bit and it got hot , shut it off it started rite back up. Ran for a min or two and died now it wont start any suggestions?

    • Austin Davis says:

      Wont start as in how…engine turns over and over but wont ignite? I would check for spark at plugs, check fuel pressure at the engine, and ignition timing.

      engine wont turn over? check for battery power to the starter and batter connections, check to make sure water is not filled the cylinders and “hydra locked” the engine. It can not compress water. The sealer works great on small leaks and seeps but if its gushing water into the cylinder you will need to replace the gasket.

  10. Nicole says:


    My 2004 Saturn Ion is loosing coolant, and I could not detect water on the floor, several mechanics told me that the oil shows water in it and most likely a head gasket is blown out.. Now I do not have the money right now to fix this properly and the car is not worth it, however I need it to ride to work. This morning it was a little chilly outside and I had trouble starting the car and white smoke coming out of the exhaust.
    Would the K&W fiberlock work for me? I do not know how to drain the radiator, but the bottle says I can add it to the coolant..
    Can you please help me with this?

    • Austin Davis says:

      The sealer DOES work for head gasket leaks but its a last resort option, AND You need to rule out any other leaks first. Get a cooling system pressure test, this should help you determine 1. If you have an external coolant leak like a water pump, 2. should help you determine if you have an internal leak like a head gasket.

      Don’t just guess. 🙁

      Once you are positive about a possible head gasket leak, I would visit your local oil change place and get them to drain out the coolant for you, install the sealer and water mix and drive for 500 miles then flush it out and go back to coolant and water. MAKE SURE it does not freeze outside, or damage to the engine and radiator can occur since there is no coolant. Keep the vehicle inside a garage, and/or place a drop light under the hood to keep the engine warm.

  11. Tony lewis says:

    Correction on previous message. Low oil pressure is coming on after about 20 minutes of driving.

  12. Tony lewis says:

    I just tried your method today. The oil cap has a little light chocolate look in it, not much. I checked the oil dipstick and it looks clean. I’m concerned as to if maybe I should flush the oil out and put new oil in it now as my low oil pressure alert is coming on after about 2 minutes of driving and it says to shut the engine off. In addition the temperature is running hot after about 20- 30 minutes

    • Austin Davis says:

      Does this engine have a lot of miles on it? IF so, you might want to use a manual oil pressure gauge (rent it from your local parts store) and screw it in place of the oil sending unit so you can see what the pressure is AT the engine. You might have a worn out, or stopped up oil pump screen that needs to be replaced or you could have a bad oil pressure sending unit sending wrong information to the dash.

      I would not “flush” the oil. Flushing can remove carbon build up inside the engine (which is good) but that carbon is also built up around oil seals, and when you remove it it can cause the seals to leak. Flushing works good as preventive maintenance but if you have lots of internal engine sludge it can cause other issues.

  13. Freda says:

    Hello Austin, I just happened up on your website and I have a question for you. I was told I have a blown head gasket (water is in my oil) and it needs to be replaced. My car is a 1999 Chevy Malibu, 6 cyl, will the Fiberlock head gasket and block repair work on my car. I’m lost without my car and I live near an AutoZone, so I can go get it. Can’t get the gasket replaced, as I am on a fixed income. Also, there is no white smoke or anything else coming out of my tailpipe.

    • Austin Davis says:

      Hi there, yes the K&W engine block seal additive should work just fine, as per my instructions not those on the can though. BUT first I would get a second opinion on the leak. Is there just a little moisture (chocolate milkshake looking stuff) on the inside of the oil filler cap?

      Are you having to refill the radiator with coolant regularly? Since you do not have any other signs of a headgasket leak I would get another mechanic to inspect it for you before you just run out and condemn the gasket as a failure. A cooling system pressure test should be done first to rule out a coolant leak, both internally (headgasket) and externally (hose or waterpump etc.)

      If they still feel there is a seep in the headgasket, yes try the sealer out and keep me posted.

  14. James says:

    Getting ready to use KW to, God willing, repair my 1999 Hoda Civic head gaskget. I’ve got a couple of questions:
    1. What size bottle to use
    2. When pouring the mixture of KW and water into the radiator

    • Austin Davis says:

      I think the rest of your question James was cut off?

      Use just the regular sized bottle, either the new Nanotech or the older K&W Block sealer in the hard metal can.

      then mix it up in a bucket with tap water and pour it in the radiator or overflow bottle then top off with tap water. Drive a total of 500 miles then drain out and refill with coolant and water mix.

  15. Mary says:

    We did have a bad water pump and before we had a chance to fix it the gasket went so we replaced the pump and put in the sealant the car is running but very rough is that normal the white smoke has gone down a lot but not completely will that all be fixed the longer we run it I live in the country amd I am scared of breaking down

    • Austin Davis says:

      The roughness and white smoke are due to coolant inside the cylinders that is trying to burn off. If the sealer can find the hole and seal it both of those symptoms should clear up. Running the engine 500 miles is the best way to help get that sealer to find and plug up the hole.

      The sealer will NOT work with coolant in the system, you have to drain all coolant and just fill up with tap water and a can of the K&W Block Sealer additive, or the new NanoTech sealer by K&W.

      If the hole is too big, or can’t seal it..then you will need to remove the cylinder head and replace the headgaskets and do a valve job which is an expensive repair.

      You should change the engine oil and filter too after the 500 miles unless it is very milky looking now, then I would change it now and after the 500 miles. Water in the oil is not good for the engine. The repair should be permanent if it works.

  16. Mary says:

    Our head gasket is blown I want to try the method you suggested but my boyfriend is afraid it will damage other things if we leave it in have you had any problems like that? I like many others do not not have the money to replace it and I was just hoping you could put our minds at ease…..

    • Austin Davis says:

      In my personal experiences with K&W Block Sealer (over 100 uses) I have never seen any negative effects from it. You ALREADY have the worst effect of all…a blown headgasket 🙂

      Now, if you do not repair the cause of the overheating the sealer will probably not do much good. In many cases a restricted radiator is the culprit of the initial overheating problem. Make darn sure there are no other external leaks, like a water pump etc. and that the radiator is clean and free of restrictions.

      Then use the sealer as I described on the page, works much better and easier than the instructions on the can. You can read 100’s of other reader comments on my site…it works.

  17. Alberto W. says:

    Used that stuff on my car last night, sweet sweet no more smoke. Got my fingers crossed it will make the 500 mile period you suggest. Thanks a million.

    • Austin Davis says:

      Oh ye of little faith! But I’ll keep a finger crossed for ya just in case. Should be fine, stuff is a great product and the repair should be permanent.

  18. Timothy K. says:

    OK, I will comment on this as well. If you have a headgasket leak you really need to try this stuff and follow Austin’s directions because it worked for me.

  19. Hilman says:

    Austin, I used the KW sealer as per your instructions and you saved me a ton of money my friend. That stuff worked great, and almost instantly. I had never heard of that stuff before until I found your website. Many many thanks to you. Let me know if there is anything I can do for you, really!

    • By Austin Davis says:

      Hilman, thank you so much for your kind words. Glad I was able to be assistance to you. You have never heard of KW before because it WORKS, and your local mechanic can not make any money on the repair with that cheap can of sealer anyone can use. 🙂

  20. Bella says:

    Stuff worked just like you said it would. Awesomeness.

  21. Garret says:

    Cant believe that stuff worked! Man o man you saved me a lot of money. Thank you.

    • By Austin Davis says:

      Thank you for your comment. I get 100’s of emails each month just like that. I should take stock in K&W block seal 🙂

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