Block or combustion leak tester for determining if CO²; is present in a vehicle's cooling system. CO²; in the cooling system can indicate a head gasket leak, cracked block or a warped head, etc. Simple to operate by adding blue detector fluid to the tester and placing tester onto the radiator; air is drawn through the liquid which will change colour to yellow if CO²; is present. Can be used in conjunction with a cone adaptor or an adaptor within the Draper Radiator Pressure Test Kit (Stock Nos. 14455 and 23420). Supplied with detector fluid. Display packed.