Recommendations requested for quality "block sealer" for head

John Shelton

Registered User
I have reworked heads. Coolant is slowly disappearing and symptoms indicate a crack or porosity in an intake port - not likely a head gasket. Current coolant is demineralized water with Water Wetter.

I'm looking for a high quality block sealer that might stop the leak. Since the car runs well, I believe this might be a "permanent" fix. I am also trying to avoid all the time and expense of another head removal, rework, and replacement.

I'd appreciate any advice - such as what's best, what to avoid.

Thanks.
 
Hey John, I just went thru that. My right side head cracked from plug to plug to plug. There's a thread with a photo I posted a few days ago. It still ran great but leaked intermittently. I had to replace the head. Had I run it much longer it would have broken catastrophicaly at #2 plug hole. I used Bars Leak Liquid aluminum to stop the leak but it was temporary and I needed to keep adding it. I hear that the black gloppy stuff with the pellets is supposed to work much better but it makes a mess in the cooling system. I put flourescent dye in the radiator and checked with a black light to find my leak. It showed right up. After awhile I didn't need the black light to find it anymore.
 
Use K&B Block Sealer Drain old coolant fill with straight water and the K&B and follow instructions to the letter. I have used it many times and it works better than anything else I have tried. I worked for a used car dealer :eek: for 25 years and have had many opportunities to try different products. Good Luck
 
Thanks for the input, guys.

I saw the pics of your heads, Mike. That's some serious crack! I'm hoping that mine is a lot smaller or just a porosity problem. Also, mine is leaking to the inside.

garsc, I couldn't find K&B, but did find K&W Block Sealer by CRC. I'm assuming that's the one you meant. It seems to be pretty popular.

For the info of others that might be in need...

From my limited research, the 2 most recommended types are what I'd call one-shot (drain, clean, flush, treat, flush, replace coolant) as opposed to a long-term coolant additive:

Sodium silicate or "water glass." They seem to jamb the leak with various fibers then seal with a material that turns glassy with heat.
Examples are K&B and Bar's Leaks.

Ceramic sealers like Irontite and Moroso Ceramic Engine Seal. Looks like they create a ceramic film. I can't tell if they have any fibers in the mix. I see that these are often recommended by "performance types." Moroso's product is the only one Summit and Jegs sell. My guess is that it might be a toss-up for performance between these two.

One frequent warning I noticed is that some will react very negatively with antifreeze causing it to goop or solidify. They recommend a thorough cooling system cleaning before and a good flushing afterward. However, there are variations of some of the products that can be used with long-term antifreeze.

Unfortunately, I found that it's impossible (or not easy at best) to find information on how some products actually work or usage instructions.
 
Can you describe the leak further, what makes you think it's on the intake side things?

Did you see a porosity concern when bolting the intake manifold in? With porosity I'd think the leak would be pretty slow, and the loss would occur during the cooling system being pressurized. Is it a cold water leak, or only when hot?
 
Forget about block sealers. Crack an egg into the cooling system; it works better than any block sealer I have ever tried. Just make sure to drop it in the radiator when it is cold and drive the car right away long enough to make sure it gets up to temp and circulates through everywhere. One guy I used to work with had a 3.8NA bird that blew head gaskets, and after putting an egg in the coolant he drove the car for another 20K miles before getting rid of it, and it never used another drop of coolant.

Mike
 
Forget about block sealers. Crack an egg into the cooling system; it works better than any block sealer I have ever tried. Just make sure to drop it in the radiator when it is cold and drive the car right away long enough to make sure it gets up to temp and circulates through everywhere. One guy I used to work with had a 3.8NA bird that blew head gaskets, and after putting an egg in the coolant he drove the car for another 20K miles before getting rid of it, and it never used another drop of coolant.

Mike

I think I remember Myth Busters even verified that this works.
 
Forget about block sealers. Crack an egg into the cooling system; it works better than any block sealer I have ever tried. Just make sure to drop it in the radiator when it is cold and drive the car right away long enough to make sure it gets up to temp and circulates through everywhere. One guy I used to work with had a 3.8NA bird that blew head gaskets, and after putting an egg in the coolant he drove the car for another 20K miles before getting rid of it, and it never used another drop of coolant.

Mike

only for a bigger hole like in the radiator, egg won't work on a hair sized crack, and its not a good idea to rely on it long term, only in an emergency would i crack an egg into my coupe! (i almost did when i blew my headgsaket for the LAST time!) hello 5.0!
 
John,

I recommend Super Glue. Use only the gel and not the normal runny stuff. Works great!

Duane,

We can always count on you for out-of-the-box thinking. But, if I didn't know better, I'd say you were a lunatic. However, I believe that any man who drinks his beer from an old gas can must be a true motorhead whose wisdom should be respected.

So, do you think about a pint poured into the coolant should do it - or do you recommend intake delivery (after the MAF, of course)?
 
Can you describe the leak further, what makes you think it's on the intake side things?

Did you see a porosity concern when bolting the intake manifold in? With porosity I'd think the leak would be pretty slow, and the loss would occur during the cooling system being pressurized. Is it a cold water leak, or only when hot?

Mike, nothing was noticed pre-assembly. The leak does seem to be very slow and with no trace of seepage anywhere on the outside. It stumbles briefly on startup but clears up fast then seems to run normally. No moisture in the oil, no white smoke, and no sign of bubbles or combustion contamination in the reservoir. I think that between cruising vacuum on one side and coolant pressure on the other, it is being slowly drawn into the the intake side and "burned."

The coolant right now is demineralized water with a little Water Wetter so maybe that's why the "white smoke" of burned antifreeze is not seen.

I can't tell whether it's hot or cold when it's leaking since it's so slight.
 
Forget about block sealers. Crack an egg into the cooling system; it works better than any block sealer I have ever tried. Just make sure to drop it in the radiator when it is cold and drive the car right away long enough to make sure it gets up to temp and circulates through everywhere. One guy I used to work with had a 3.8NA bird that blew head gaskets, and after putting an egg in the coolant he drove the car for another 20K miles before getting rid of it, and it never used another drop of coolant.

Mike

MadMikey, I've heard about this too...but I just don't have the huevos to try it.;)
 
MadMikey, I've heard about this too...but I just don't have the huevos to try it.;)

I've done it on 5 cars now, and it has never caused any trouble in any of them.
First was my 91 5.0 cougar when it was stock. The radiator on that would leak from the side tank, but only right after you turned off the engine. One egg, and it never leaked again, and I still had the same radiator in the car for almost 2 years afterward.
Second was my 79 firebird that sprung a leak in the heater core in november. One egg and the leak stopped for the whole winter, which was all I needed. When spring came I bypassed it just to be safe, and then I sold the car that summer.
Third was my ex-girlfriend's 91 tbird 3.8NA. It sealed up the head gaskets good, but then she ran the car out of oil a few months later so I swapped a motor in it.
Fourth was a friend's little 80s dodge pickup with the mitsubishi 4-cyl motor. The head gasket was leaking out between the head and the block. One egg held him over for a few months until it got warm enough to do the head gasket on it.
Fifth is my 89 XR7 that I daily drive right now. I got tired of the slow leak out of the thermostat housing, so I dropped an egg in the coolant and haven't seen my low coolant light in a couple months now.

I have never tried it on a cracked head, so I don't know how well it would do in that situation, but for how cheap an egg is, its worth a try. Basically the way it works is the egg goes through the water pump and gets scrambled, then pressure builds in the cooling system and forces the egg into the crack/hole. Then the coolant heats up and it cooks the egg, which expands as it is cooked and it fills and seals the leak.
 
It stumbles briefly on startup but clears up fast then seems to run normally.
...
The coolant right now is demineralized water with a little Water Wetter so maybe that's why the "white smoke" of burned antifreeze is not seen.

If you want to know for sure, I'd let it sit over night and then pull plugs. If you're burning antifreeze, it should be obvious on the plug.

The white smoke is from water more than anything else, it's essentially steam. I think you'd know if you were loosing that much coolant.

The best way to be sure of if you're burning coolant or not is the plugs.
 
Need the yolk?

That's wild, I thought it was a joke to crack an egg into the coolant system. Should the yolk be put in there, or just the white?
 
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