It is the ability of the Plymouth radiator and coolant hose to provide a pathway for the heat to be carried away from the engine; which will help keep it running for over 100,000 miles. Without the engineers design to remove the heat that Plymouth engines produce, it would not be able to operate efficiently or with the power they can now produce. The radiator hoses are constructed of similar material as the hydraulic hoses on your vehicle. The differences include the diameters of the coolant hoses are bigger and the walls of them are also thinner. The reason for the thinner walls is they do not have to contain the level of pressure the hydraulic hoses do, but the reinforcement in the walls is still present to help give them a long life. The Plymouth radiator and coolant hoses also have to withstand a higher level of heat than their hydraulic counterparts. This is why instead of just cracking like the hydraulic hoses, radiator hoses have their walls thinned out over time causing the leaks to occur. This is called a ballooning effect. This ballooning effect increases the diameter of the radiator and coolant hoses that breaks apart the reinforcement the walls were made with. This is how a leak will occur on your Plymouth. This ballooning will occur where the hoses are subjected to the greatest level of heat on the Plymouth engine. It is usually the upper radiator hose that handles the hottest coolant, because it is attached to the exit portal or water neck at the top of the engine near the thermostat housing. This is the place that should be checked if there is a coolant leak on your vehicle.