Bondloc gasket seal type b518 is a red smooth thick paste easily applied cures once confined between the parts to form in place a tough flexible gasket gives an instant low pressure seal used for fuel and water pumps split crank cases on engines gearbox covers engine thermostats air compressor end caps engine timing cam covers onto blocks pump couplings fuel tanks on small implements chain saws lawn mowers etc use b518 for dressing gaskets spacers etc specifications resin modified urethane acryl