The Mazda radiator and coolant hoses are the conduits used by the engine to send hot coolant to and from the radiator so heat can be dispersed. They are made out of a flexible polymer that is reinforced to improve their ability to withstand the heat related stress they are constantly exposed to. The location of the radiator and coolant hoses are easy to spot on your Mazda. The upper hose on top supplies the radiator with hot coolant from the engine. The bottom hose is the supply hose that supplies the engine with cold coolant from the radiator, and is connected to the inlet side of the water pump. Mazda radiator hoses are constructed from a flexible reinforced polymer. Because they are made of a polymer, they will wear out in time due to their constant exposure to extreme heat. Over time the radiator and coolant hoses will show signs of weakening. This can be identified by the expansion in the circumference of the leaking (or potentially leaking) hose. The location of this expansion is most commonly at the exit port of the hot coolant from the engine on the upper hose. This is the location of the most extreme temperatures the radiator hoses will experience on your Mazda cooling system. Other common place for the radiator or coolant hoses to have a leak is anywhere they come in contact with a metal component. The transfer of heat at the contact point or just the continuous rubbing against metal on the polymer will in time be an area prone to leak. Because of this an inspection of the engine and hoses under the hood of the Mazda should be conducted on a regular bases.