Using K-Seal

It couldn’t be easier to use K-Seal products on your engine. Whether you’re using K-Seal, K-Seal Ultimate or K-Seal HD, you can find full instructions here.


Permanently seals leaks in the head, head gasket, block, radiator, heater matrix and water pump.

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A unique formula specially developed to permanently repair serious head gasket and porous block problems

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K-Seal® HD

Designed for large engines including HGV’s, tractors, heavy plant and other commercial vehicles.

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How Does K-Seal Work?

K-Seal is a specially-developed, scientifically tested formula containing ceramic microfibers and copper particles. When added to an engine’s cooling system K-Seal will flow harmlessly through, suspended in the coolant. However, if a leak is present, K-Seal will quickly coagulate around the damaged area and repair the crack permanently.

With over 6 million bottles sold worldwide, K-Seal is the only coolant leak and head gasket repair liquid to be scientifically tested and compliant with the ASTM D3147 standard. Testing by Brighton University showed K-Seal is capable of permanently sealing holes of up to 0.635mm in diameter, and cracks up to 0.254mm wide by 12.7mm long. As most holes and cracks are significantly smaller than this, K-Seal can provide a permanent, guaranteed fix for the majority of leaks.

How to use K-Seal

K-Seal is Scientifically Tested

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Expert Advice

Head Gasket Failure? Cracked Head or Block?
Leaking Radiator?

Expert Advice

Where to buy K-Seal

Have any of these symptoms? K-Seal could save you thousands on a workshop repair. Search for a stockist today!

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