Bar's Leaks carbon fiber block seal head gasket and cooling sealant (p/n HG-1) is a strong formula designed to permanently seal any coolant leak in plastic, cast iron, copper and aluminum radiators, heater cores, freeze plugs, gaskets, intake manifolds, cylinder heads and engine blocks. It repairs blown head and intake gasket leaks, seals cracked cylinder heads and blocks, stops heater core and radiator leaks, fixes leaking freeze and core plugs, and stops overheating. It works in any water-cooled car, truck, van or SUV. The formula combines an antifreeze-compatible liquid glass (sodium silicate) with aramid and refractory fibers