Draper Expert Combustion Gas Leak Detector Kit and Fluid Range - Draper Expert 23257, Expert Quality, 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. Draper Expert 23257 Combustion Gas Leak Detector Kit