Belts and hoses that fail can sideline your truck when you least expect it. Carrying spares can save time and money when one of these critical parts fails on the road. Even better, take the time to periodically inspect them for signs of wear and replace any weak links before they become a problem.
Cooling system leaks are among the most frequent maintenance problems. Coolant hoses can develop leaks from abrasion, punctures, loose clamps and an improper fit between the fitting and the hose. A hose should fit snugly over the mating tube. During inspection, squeeze the hose along its length to detect cracking, softness and wear spots. Hoses that are cracked, swollen or dried instead of resilient should be replaced, advises the Technology and Maintenance Council.
Most hoses are manufactured with woven reinforcement in the walls for strength and rigidity. They are sized by their inside diameter. Standard-quality coolant hose is made of black rubber EPDM hose. Silicone hose is more expensive but is tougher and lasts longer in high-heat applications, providing higher temperature tolerances than EPDM hose, and it does not dry out or crack as quickly.
When replacing hoses, lubricate the ends and fittings with water or a solution of water and mild liquid soap. To avoid an adverse chemical reaction and deterioration of the hose, do not lubricate with ethylene glycol, propylene glycol or any petroleum-based products. Silicone-based oils should not be used with EPDM hose, says TMC.
Gates Rubber Co., a major supplier of belts, clamps and hoses, recommends checking coolant hoses when the system is flushed or whenever servicing of the radiator or water pump is required. Hoses showing obvious signs of wear and those more than 4 years old should be replaced, Gates advises. Since EPDM hoses tend to bond to metals, removal of coolant hoses from fittings must be done carefully. Avoid forcing or prying a hose to prevent damaging the fitting. Gates recommends slitting the hose lengthwise at the fitting to loosen it for removal.
During four years of testing on fleet vehicles, Gates engineers traced the cause of most coolant hose failure to an electrochemical attack on the rubber compound in the hose. Known as electrochemical degradation, the condition occurs because the hose, coolant, and engine and radiator fittings form a galvanic cell, like a battery. The chemical reaction causes the formation of microcracks in the hose tube, allowing the coolant to attack and weaken the hose reinforcement, Gates reports.
To check a coolant hose for the effects of ECD, the company recommends that you squeeze the hose near the clamps or connectors. If the hose feels soft or mushy, chances are good that the hose has been attacked by ECD and should be replaced. There should be no difference in the feel between the middle and ends of the hose. Upper radiator hoses and heater hoses tend to fail first because that is where the temperatures are the hottest.
According to Gates, it is not uncommon to find hose failures due to electrochemical damage in vehicles driven fewer than 25,000 miles. The timely replacement of a coolant hose can prevent a roadside breakdown, as well as damage to the engine. When replacing a hose, Gates recommends also replacing the hose clamps. While clamps are typically made with stainless steel bands that resist corrosion and damage, they are secured by carbon steel screws, which can fatigue and lose strength.
