K seal ultimate will permanently fix leaks in the head gasket head and block of all water cooled engines the unique ceramic micro fibres in k seal ultimate target the pressure differentials at the point of failure first sealing the leak and then curing to make a strong and long lasting repair k seal ultimate will even fix leaks where the cooling system is over pressurising due to combustion gases leaking into the coolant just follow the instructions on the bottle use k seal ultimate and sa