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Your cart is empty.Experience the ultimate solution to coolant leaks with the K-Seal ST5516 HD, a multi-purpose, one-step permanent coolant leak repair. Our powerful formula works seamlessly with all antifreeze, making it a universal fit type for all your needs. No need for draining or flushing your system. This heavy-duty sealer was designed specifically for HGVs, tractors, heavy plant and other commercial vehicles. The K-Seal ST5516 HD, also known as a head gasket stop leak, works by sealing leaks efficiently and permanently. It also doubles as a radiator stop leak, effectively putting an end to any leaks in your radiator. The permanent leak sealer is easy to use - just shake, pour, and go. This product excels in fixing cracks and leaks in several components including the radiator, head gasket, freeze plugs, cylinder heads, heater core, water pump casing, and engine blocks. With a single 8 fluid ounce bottle of our coolant leak sealer, you can treat up to 20 quarts cooling capacity. This heavy duty stop leak sealant is a must-have for all your coolant leak issues. So, forget your coolant leak worries with the K-Seal ST5516 HD. Experience the power of a seal stop leak that stops leaks permanently, offering peace of mind and extended life for your vehicle's cooling system. Trust the K-Seal coolant leak repair for a lasting solution to all your coolant leak problems.
Customer
Reviewed in the United States on February 7, 2025
Great ProductFulfilled Expectations
Eddie Bagby
Reviewed in the United States on January 31, 2025
Works very well
pete fonseca
Reviewed in the United States on January 18, 2025
it worked on a 2017 Ford F250 6.7 power stroke. the dealer wanted to charge me 7k to fix it
Donald Cook
Reviewed in the United States on January 12, 2025
I used this on a tractor that has had a slow leak for years. One application following the directions and it worked great. Thanks
Kyle
Reviewed in the United States on November 18, 2024
Flush cycle and then back in with this product and water and then dump that water out to be able to put coolant back in it to be able to put it back in the service and a you know winter time scenario or summer to Winter scenario this stuff you just poured in and let it do its job and you're done you don't have to drain the coolant out you don't have to go through a big process of it throw it in there let her idle for a while they're back in service and go to work make some money and stuff keeps equipment and stuff operating when you don't have a chance to take it down or take it out of the field for a while and it'll get you by or it'll work as a permanent fix I wish I could get buy stocking in this stuff
johnnyjohnny
Reviewed in the United States on November 16, 2024
i used this stuff for the first time 8mo ago after reading the great reviews. i was blown away as it quickly sealed up an old waterpump on my 22yr old chevy. that it lasted 8mo.s was impressive, but the other night the water pump again began leaking. i immediately ordered this on amazon and a day later put half the 16oz bottle in, and it immediately sealed up the same waterpump. given this waterpump is super old, i don't know how long it will hold this time, but i'm already impressed by this stuff. and i still have 8oz of it left. NOTE!!!...be warned that you need to really shake this stuff up per the directions, prior to using.
Travis Maurine
Reviewed in the United States on October 30, 2024
The low coolant notification came back on within 40 miles. Didn’t even get me an extra mile.
Customer
Reviewed in Canada on October 26, 2024
saved me a lot of money
Dawg
Reviewed in Canada on December 18, 2023
I have 2015 long nose Peterbilt. Had a slow cold leak from the bottom of the radiator (only would leak as the engine cools down) then I would have to add about 1 litre of coolant the next morning. After I added this product a few weeks ago, I’ve added nothing and the coolant level is still at the top. Excellent quick fix rather than new radiator.
Alberto
Reviewed in Mexico on June 28, 2021
Funciona y es fácil de usar
Ravi
Reviewed in India on April 24, 2021
i poured 200 ml for my 7.2 l coolant capacity radiator. then ran idle engine for 30 min. It sealed whatever head gasket leakage was present. The service station asked 15,000 to replace head gasket. This cost much less - 4400. Excellent product.
A.F.
Reviewed in the United States on October 21, 2020
I bought these to use on my 2011 f350 diesel with a leak on one of the front seals behind the water pump, if I wante to fix it right I would have to take the whole front end of my truck, fan, water pump, and even the front crank cover, no way,, so I bough this mainly because the manufacturer stated that this were permanent, not temporaty fixes, so Bought it, pour just half the bottle and wow! it stoppe, I was impress, but then a cold front arrived and neded to use my heater (wich I just replaced last winter with an OEM heater core) and bam!!! mildy warm air was comming out of the vents, so.... I guess i will now have to replace the heater core wich I can do in about 5 hours (take center console out, and then dash and it literally takes less than 5 minutes to take the old heater core out and put the new one in) I guess is better that taking the front endwhat I would do different now it would be using this product and then cutting my heater core lines and splicing then togheter to bypass my heater core, let this stop leak do the magic and then flush the old coolant, put new one in and then connect back the heater lines
Customer
Reviewed in India on June 25, 2018
There was a crack in head gasket of my car and coolant was leaking from there. Results in engine overheating.I added Kseal HD in in coolant and I had driven 5000 KM after that and crack is healed hence no overheating.Authorised service centre had asked to change the head gasket , that could have costed me around Rs. 75000.Local mechanic suggested to weld the crack. That too have costed around Rs. 20000.But Kseal costed me only Rs. 3500.And it really worked for me.
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