BlueDevil Products 00205 Radiator & Block Sealer - 16 Ounce

I used blue devil because of the comments. My water pump went out on me and cracked the block right behind water pump due to over heating. After replacing water pump and putting blue devil in the radiator I watched a spray of water go from spraying water out to a trickle and then to nothing and the heat on the motor dried up all moisture. Drove my truck up the road about 8 miles and back with absolutely no issues. I’ve never seen any product work like it says it does. Blue devil does work. It took 45 minutes like it said but every time the thermostat cycled the leak got less and less. It’s unbelievable it actually sealed a cracked block.

I was going to sell my car but it only has 96k miles ...it "had" a timing chain cover leak (about $1,200 including chain to fix) and if you put pellets in there are brown remnents evrywhere BUT with Blue Devil ...your system is the same color as your raditor fluid AND the leak is stopped ...p.s. heater core too but who needs heat in Texas

Worked well for my radiator leak.

Works advertised. Great product and value.

This product was recommended to be the best to buy for this purpose. However, if you have a big leak, forget about buying any product. Nothing works or worked for us except replacing the entire radiator! Wasted my money, since this is the most pricey of these products.

I had a crack in a SBC 350 that was a junkyard find in the block (just behind the push-rods). I was putting it in my 1936 Pontiac. I saw the bump in the cast and was hoping it was a cast imperfection but alas my mechanic was right and I was losing coolant into my oil. I flushed radiator with water, filled it up with just water, drilled out inside of thermostat, and dumped this in, let it idle for the hour that it says and then let it cool overnight. The next morning I went out and the radiator was still full of blue fluid (I couldn't believe it!) and oil level was dead on the stick. Haven't had a problem since! Thanks BlueDevil!

Great stuff

Honda Civic, hairline crack in cylinder wall, had block and head milled EXACTLY flat, new head gasket too. After calling and talking with a technician there, I used High Temp JB Weld on coolant side of cylinder tube after routing a 1/16th inch slot along the hairline crack and cleaning with acetone, let that cure exactly per directions. Then I used Blue Devil product exactly as specified. It worked for two days. Not a minute more. New short block the expensive answer. Previously, on a Cadillac NorthStar engine, Blue Devil worked perfectly on a bigger crack through the outside of the engine block into the water jacket.