K&W 401016 Block Seal Permanent Metallic™ Block & Radiator Seal - 16 Oz

I have used this product for over 40 years. WATCH the video on "how to use". It is a great product. Not to be used with ANY anti-freeze, JUST WATER and make sure the engine is hot/operating temperature. After you drain the system, let it set up for at least 2 days. This is the difference between this product and all the other crap out there. This is a good fix, not a band-aid.

These do work! With certain assumption, depends on the leak or crack in your head gasket. I followed the directions from TrustMyMechanic . com in the you tube channel. [...] . His directions made more sense to me. You really have to drain your existing coolant out, flush it a couple of times, then fill it with tap water and then poor this bottle into the radiator cap opening. Then just drive your car for at least 500 miles. It took me about a week of driving to work and back to hit 500 miles. I check my radiator every day to top it off with water before going to work and noticed it stop leaking after about 75 miles on the odometer. So what does that mean...you really have to drive it around, get the engine hot enough and let the water/block seal get into the seams of the crack/leak. The directions on the bottle may work, but I think by doing it this way, I think it works a lot better. Like I said, it stopped leaking at around 75 miles into the 500 miles. I guess if you drive it over 500 miles and it is still leaking, then I think the crack/leak is way to big for this product to work. Or it could be leaking outside of the cylinder head. So after the 500 miles, verify that it stopped leaking by openning up your radiator cap and looking into your radiator. The top of the radiator should still be wet, there should still be water floating around at the top. If you can see the radiator fins and it's bone dry, then you still have a leak. If you are good, drain the tap water/block sealer, then flush it a couple of times. Then fill it up with coolant for your car. I use this product on a 2005 Toyota Tacoma Pre-Runner. Symptom of a crack/leak in your head gasket: Got a P0300 (random misfire), P0304 (cylinder 4 misfire), P0306 (cylinder 6 misfire). For this truck, when you drive it around town, you can hear water swooshing back and forth inside the engine bay. This is because when there is a leak in the gasket, the pressure and gases from the cylinder head pushes back into the coolant chambers and creates bubbles/air pockets thus there is open space in your coolant block that allows the coolant to move around. So if you hear that, it's an indication that you got coolant issues. Also, you will be losing coolant everyday or two when you check your radiator. Hope that helps...

This seller is re-selling “bargain” products that are defective and that they got on sale. The price label reads $3.99. The product is bad and unusable (completely solid). This review is not about the product as originally made. It’s about this seller. Stop selling junk!

Great product, unfortunately my head gaskets were too bad to seal this way

So far so good. I used this sealer close to Trust My Mechanic instructions (you tube). I did drain and flush cooling system several times before use of sealer. All antifreeze flushed out of system. I drained system by removing hose at bottom of radiator. Also I removed threaded drain plug on block each time I flushed. I added sealer after mix with water in 1 gallon jug. Half was put in to radiator the rest was put into thermostat opening. Thermostat was replaced and used during the 500 mile run in. Radiator was filled to the top before car started. Heater was turned on wide open for first 50 miles. I only have 250 miles on car so far but the internal leak has stopped. I have not added any water to cooling system after the addition of sealer. Water lever is good in overflow tank. Car is not over heating. The plan is to put 500 miles total on the car then drain cooling system and put in antifreeze 50/50. I hope it works. Check out Trust My Mechanic instructions on you tube. He has a high success rate with this product. Good luck. Update sealer failed after a few weeks of use. Would not buy again. Looks like no short cut in these kinds of situations. I wound up just buying a used engine and rebuilding it. Then replaced the one in car with it.

Slow down the block crack, but never fixed it 100%

Works as it should

Very good product

I used the this product twice and finally it worked. First time, I followed the instructions blindly without paying attention to capacity. I mixed it with 3 quarts of water. But I was only able to put half the solution to the radiator because my car has small capacity. So after doing all the things, My cars is still loosing coolant. After thinking it over, I decided to give a 2nd try. This time I mixed it with less water so I managed to put the whole can of k &w into cooling system. After going through all the procedures according to the video, it finally worked. Now I hope it will last a long time.

This item arrived on time and was just what I needed to seal my leaking rad.

Good product to return.

it worked to seal my leak but my bottle showed up almost completely dried out. Had to bash it with a screwdriver to get it out of the bottle and then beat it into submission to mix it into water before use.

I honestly didn't really expect it to work but it was worth a try