Abstract: The transparent radiator hose is configured for use with the engine cooling system of a vehicle. The transparent radiator hose diagnoses the interchange of the cooling fluid pumped through the engine cooling system with a system fluid selected from the group consisting of the engine oil, the transmission fluid, and the power steering fluid. The transparent radiator hose comprises a modified radiator hose, a plurality of tracer dyes and an ultraviolet lamp. Each tracer dye is a fluorescent compound. There is a one to one relationship between the plurality of tracer dyes and the group consisting of the engine oil, the transmission fluid, and the power steering fluid. The modified radiator hose transports the cooling fluid used to cool the combustion engine. The modified radiator hose is partially transparent such that the cooling fluid can be seen through the modified radiator hose. The ultraviolet lamp generates ultraviolet radiation.