Coolant hoses can certainly wear out in the life span of your vehicle -- in fact, consumers reported in a national survey that two to three times as many radiator hoses failed while driving in their vehicle's fifth year than its fourth. And according to the Car Care Council, 30 percent of the vehicles needing under-the-hood repairs needed new hoses or belts.
The average four-year-old car has been driven nearly 70,000 miles, a mileage interval that most technicians believe is the time many parts wear out. Coolant hoses are no exception and the age of the car is a good indicator of when replacement should be considered.
Traditionally, hoses have been visually inspected for failure from the outside. But with today's cars, that method isn't always the best since hoses usually fail from the inside where weakened elements can't be seen and their symptoms not always obvious.
Therefore, replacement of the coolant hoses, especially the radiator hoses, every four years is recommended, regardless of physical appearance.
The materials now used in your engine's construction are different than those of years ago. Cast iron has been replaced with aluminum, plastic and brass. Used together with the coolant, which is also conductive, these dissimilar materials can create a sort of battery with the hose conducting electricity through itself. The electrical current can create tiny cracks in the hose tube which eventually weaken and cause the hose to fail. This phenomenon is called electro-chemical degradation or ECD.
The higher operating temperatures in cramped engine compartments result in hotter temperatures for hoses. While increased temperatures result in greater engine efficiency, heat also increases the rate of ECD in hoses! In fact, for every 18-degree increase in temperature, the rate of ECD doubles. Heat can also weaken some t reducing the overall burst pressure and cooling system performance.
Vibration from rough idling engines weakens other types of hose reinforcements -- again leading to premature failure. Also, abrasion from sharp surfaces within the engine compartment can slowly rub through the outer cover of the hose, eventually causing it to burst. Cuts and nicks on the outside of the hose also contribute to premature failure, but oil is a more common threat. A hose exposed to oil will be prematurely weakened since the oil actually attacks the rubber compound on the hose cover. Any of these signs indicate a hose that could fail at anytime.
Courtesy of the Car Care Council