K&W Block Sealer

K&W engine block sealer

How much KW Sealer should we use? is the 16oz can enough for a Chevy s-10 dual core radiator?  Our truck over heated on my son Christmas blew head gasket and was blowing white smoke.

One mechanic  said  to replace the intake manifold and radiator,  a friend is helping fix it doesn’t think  the intake manifold is bad  so far we  did head gaskets & bolts a water pump, spark plugs and new radiator  after a oil & filter change  we still have oil that is milky.

He wants to do a compression test  but I cant drive it there with out making it worse will this fix that?  Or should I wait  and have the heads shaved and a new gasket set

I am running on empty cash wise this month  and  really need wheels right now  but will wait if driving it will put it further in the hole  any advice would be greatly appreciated
thank you for your time


Hi there,

The 1 can of K&W Block Sealer is plenty for your vehicle. You will need to be able to start and run the engine for the sealer to work though. So if you have lots of water/coolant dumping out of the tailpipe where the engine will not stay running, the sealer will not work.

If you can get the engine to start and stay running, then use the sealer as I described on this site…not as per instructions on the can.

My tried and true instructions for Sealer are:

1. Empty ALL coolant from the engine, radiator as best you can – sealer will not work with coolant.

2. Pour contents of the can in a bucket, mix in plain tap water into bucket and stir contents.

3. Pour contents of the bucket into the radiator and top off with plain tap water.

4. Run the vehicle for 500 miles total drive time.  You don’t have to drive 500 miles all at once, but the faster you put those miles on the better.

5. After 500 miles, drain out radiator and fill up with 50/50 water coolant mix and pray that it worked. That is all, I don’t take out the thermostat or anything else.  We have had a 80% success rate on 100’s of cars in our shop.

Warning  – You will NOT have BOIL OVER or FREEZE protection during those 500 miles so make sure to keep the engine and radiator from freezing.


Posted in: Head Gaskets

27 Comments on "K&W Block Sealer"

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  1. Jeff volkman says:

    I have a 2004 ford ranger 69,000 miles on it put new spark plugs wire etc also put 3 injectors on it still misfiring a little bit don’t have white smoke but a good amount of water coming from tailpipe any suggestions?

    • Austin Davis says:

      Get a cooling system pressure test to determine if you have an internal leak, if so, use the sealer. Water could be just normal condensation thanks to Ethanol gasoline, miss might be due to internal wear/damage in the cylinder or valves…a compression test is what I would do to check.

  2. Jake Wacker says:

    Should I run the heater while driving the 500 miles with the sealer in the systems? Or will that hurt it ?

    • Austin Davis says:

      Run the heater for a few minutes to remove any air pockets that might be in the system, then top off radiator as needed, but you dont have to use the heater anymore unless you need it. Wont hurt it.

  3. freda says:

    1997 deville smokes no oil in water but a lot white smoke when start up clears up after warm heater works great not running hot please help

    • Austin Davis says:

      I would get a cooling system pressure test first, but you might have an internal coolant leak, like a head gasket that is dripping cooling into the cylinders overnight. The sealer would be a good option if that is the case. I would expect you would be constantly adding coolant if there was an actual coolant leak, so check the radiator level.

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