According to the Car Care Council, nearly 30% of the vehicles they have inspected have belts and/or hose that need replacing. Yet in most cases, the vehicle owners were totally unaware of the condition of these critical parts. Everybody wants a reliable vehicle to drive, but not many people are forward-thinking enough to practice preventive maintenance beyond the barest of basics. After all, preventive maintenance costs money and nobody likes to spend money "unnecessarily." We put unnecessarily in quotes because we want to emphasize the fact that most consumers do not appreciate the benefits of preventive maintenance when it comes to belts and hose. Changing the oil and filters every so often they can understand. Oil and filters get dirty and need to be changed. Replacing spark plugs periodically they can also understand. Spark plugs wear out and can become fouled. But replacing radiator and heater hose that have not yet failed? No way. What people often learn the hard way is that belts and hose age, and what happen when they fail. The coolant leaks out and the engine overheats. Most belts and hose fail from the inside out. Rubber hose (which are actually made of neoprene or other synthetic materials) can deteriorate with age and exposure to heat. Today's hoses can last 8 to 10 years with no problems, but eventually the hose material will become hard and brittle. Tiny cracks develop in the rubber which eventually cause the hose to split, blister or leak. Oil on the outside of coolant hose can also accelerate the breakdown of the hose material. This type of deterioration can usually be seen on the outside. But what often escapes detection is what is going on inside hose. Today's bimetal cast iron/aluminum engines and aluminum radiators can create conditions that set up an electrical current in the coolant. The inside surface of the hose becomes a conductor, which causes the material to pit and weaken. Cracks and striations tend to form near the ends of the hose that eventually eat through from the inside out causing the hose to fail. Yet until the failure occurs, the hose may look good as new on the outside. This type of deterioration can sometimes be identified by pinching hose near each end with your thumb and fingers. If you feel "ridges" or "voids" inside the hose, it is experiencing electro-chemical degradation (ECD) and needs to be replaced. But even this type of inspection may not catch all the bad hose that are out there. REPLACING ENGINE HOSE PRECAUTIONS WARNING: DO NOT attempt to loosen or remove a coolant hose or fuel hose on a hot engine. Wait until the engine cools. If replacing a coolant hose, loosen the radiator or reservoir cap to depressurize the cooling system. If replacing a fuel hose, the fuel line can be depressurized by locating the schrader test valve on the fuel injector fuel rail and depressing the valve. Or, you can locate the fuel pressure regulator on the injector fuel rail and apply vacuum to the regulator with a hand held pump. Or, you can momentarily start the engine, remove the fuel pump fuse or relay and let the engine run for a few seconds until it stalls from a lack of fuel. HOSE REPLACEMENT TIPS Replacement hose must be the same type, size and length as the original. Original equipment ring type clamps (which may lose tension with age) on coolant, fuel, vacuum or emissions hose should be replaced with screw clamps. If a coolant hose does not seem to fit properly, try switching it end for end. The inside diameters of the ends may be different depending on the application. Molded hose is also designed to fit one way. Never pry a coolant hose loose with a screwdriver or similar tool. Doing so can crush or damage the pipe connections on the heater core or radiator, creating a potential leak path. If the hose won't come off, it should be slit with a knife and peeled off. A good time to replace coolant hose is when changing the water pump or radiator. New hoses might also be needed if the engine itself is being replaced or overhauled. Hoses with over 100,000 chilometri of service should be replaced. When replacing an upper radiator hose, pay close attention to the condition of the thermostat housing, too. Aluminum housings can become badly corroded with age and may not seal properly when the new hose is installed. If the housing is pitted and rough, replace it. HOSE DESIGN Fuel, emissions and vacuum hose are made of special materials because of the liquids and vapors they carry. Fuel hose is made to withstand gasoline and alcohol, and is reinforced to hold pressure. A fuel hose is usually good for up to five years of service. The reason they need replaced is due to internal flaking of the hose which releases small pieces of rubber that can end up plugging fuel injectors or carburetor circuits. The pressure rating is printed on the hose, so be sure you use the correct type of fuel hose for the application. Hose that is pressure rated for carbureted engines (7 to 10 psi) must never be used on fuel injected engines (35 to 80 psi or higher). The higher rated EFI hose can always be used on a carbureted application but never the reverse. High pressure EFI hose often require special high pressure "rolled edge" clamps rather than standard clamps or spring clamps. Some EFI hose also use special connectors. PVC emissions hose is designed to withstand oil and fuel vapors, but is not designed to handle internal pressure like fuel hose. Emission hose need replaced when age-weakened rubber collapses under vacuum, which prevents the necessary venting of crankcase blowby vapors through the PCV valve. Hose also will become plugged with accumulated crud that blocks the flow of air through the PCV system, causing sludge to build up rapidly in the crankcase. If not corrected, this can lead to oil breakdown and major engine damage for the customer. The PCV hose should be inspected (and replaced if necessary) when the PCV valve is inspected (typically every 50,000 chilometri). Vacuum hose are designed not to collapse under vacuum, but they are not intended for carrying liquids, gasoline or oil. So be sure to use the correct hose application for the job. Replacement of vacuum hose is important in the sense that if one develops a leak, it can lead to all kinds of driveability and emissions headaches. Fairly expensive when compared to other types of hose, power steering hose usually is not replaced unless it is leaking. However, power steering needs to be inspected periodically for leaks or damage because such a hose failure can cause a loss of power steering assist. Power steering hose comes in two varieties: low pressure hose for the return line, and high pressure for the supply side. Using the right hose is critical. Flushing the power steering pump, hose and steering gear is also recommended after hose replacement if the old hose were flaking internally. Air conditioning hose comes in two basic types: barrier and nonbarrier. The latter is okay for older vehicles that have R-12 A/C systems, but is not recommended for newer vehicles or those that have been converted to R-134a refrigerant. If a leaky A/C hose is found to contain sludge or debris, the system should be flushed and an in-line filter installed to prevent orifice plugging and to protect the compressor. WHEN TO REPLACE ENGINE BELTS Belts likewise deteriorate with heat and chilometroage. Every time a belt passes around a pulley, it bends and flexes. This produces heat in the belt which hardens the rubber over time. The wear process can be greatly accelerated if the belt is loose and slips. The additional friction between belt and pulley will make a belt run even hotter. After millions of such journeys around the pulleys, even the best drive belt begins to suffer the effects of age. The rubber begins to crack and fray, and the internal cords become weakened and brittle. Eventually the belt breaks, and at that point, all cooling is lost along with whatever other functions were powered by the belt (water pump, alternator, power steering, air conditioning, etc.). You can't always determine a belt's true condition by appearances alone. Any belt that is obviously cracked and frayed should be replaced. But with many of today's "bandless" belts, there is no outside cover to peel loose and betray the belt's deteriorated condition. A belt may appear to be like new on the outside yet be on the verge of failure because of weakened cords inside. Most V-belts look the same on the outside, though there are significant differences inside that affect the life of the belt. One of the most obvious differences is in the placement of the tensile cords that hold the belt together and prevent stretching. Tensile cords are usually made of twisted polyester and run the length of the belt. Additional reinforcement is provided in the "undercord" area of most belts through the use of crosswise layers of fabric. Some manufacturers use chopped fibers blended into the rubber. Placement of the reinforcing tensile cords in the belt can affect belt life. One can see where the larger cords are placed by looking at the sides of the belt. "Center cord belts" have the tensile cords near the center and are less costly to manufacture because they produce less waste during cutting and trimming operations. Other belts, called "high cord belts," have the cords positioned closer to the top. Positioning the cords at the widest part of the "V" allows up to 40% more reinforcing cords to be used, which makes for a stronger belt. Therefore, high cord belts usually last about four times longer than center cord belts. But all high cord belts are not long-life belts. If the manufacturer uses low-quality materials and does not get a good cure when the belt is vulcanized, that particular high cord belt may not last as long as a center cord belt. Another variation in V-belt designs is the notched belt. Though not used as original equipment, it is offered as an aftermarket replacement. The notches make the belt mor…

Fonte: AA1Car.com