Replacing the hoses of the A/C refrigeration lines should be entrusted to a car service workshop with the necessary equipment and qualifications to safely discharge the system. Never disconnect the refrigeration lines until the system is completely discharged!
General information
Under the influence of high temperatures that take place in the engine compartment of the car, the material of the rubber and plastic hoses laid inside it begins to break down over time. All hoses under the hood should be inspected regularly for cracks, leaks, signs of material hardening and loose fittings.
Detailed information on checking the condition of the hoses of the engine cooling and interior heating systems is set out in Section Checking the Status of Components.
Clamps are used to fasten some, but not all, hoses to their fittings. Check the tightness of the hose clamps - loosening of their fastening leads to the development of leaks. If the hose is fitted to a fitting without a clamp, make sure that the end of the hose remains flexible enough to fit snugly around the surface of the fitting.
Vacuum hoses
Typically, all vacuum hoses, especially those used in emission control systems, are color-coded or colored stripes are fused into their walls. Different systems may have different requirements for the wall thickness of the vacuum hoses they use. Hoses must provide varying resistance to collapse, temperature effects and other factors. Make sure that the replacement hoses meet the parameters removed from the car.
Usually, the condition of the vacuum hose can be reliably assessed only by removing it from the car. If you have to remove more than one hose, first take care to clearly mark them in order to ensure correct connection during assembly.
When checking the vacuum hose, do not forget to also evaluate the condition of its plastic fittings - inspect the fitting for cracks and make sure that the hose fits snugly on it. When pulled onto the fitting, the hose must not deform unevenly, causing vacuum loss.
A short piece of vacuum hose with an internal diameter of about 7 mm is an excellent stethoscope, with which it is quite easy to identify sources of vacuum loss. One end of the hose is pressed against the surface to be checked, the other end is pressed against the ear. Vacuum loss is always accompanied by a hiss.
When listening to components, be careful not to touch moving components inside the engine compartment, such as drive belts, fan blades, etc.!
Metal lines (every 15,000 km)
Sections of metal tubes are often used as fuel lines. Carefully inspect all rigid fuel lines for dents, kinks or other deformations. Make sure that there are no cracks or signs of the beginning of their formation.
If any section of the metal line is to be replaced, use only seamless steel tubing as replacement. Copper and aluminum tubes are not suitable as replacements, as they do not provide sufficient resistance to the vibrations that occur in the system during engine operation.
Carefully inspect the metal brake pipes at the points of their connection to the GTZ and the restrictor valve (if provided). Pay attention to defects such as cracks, try to look for signs of loose fastenings. In case of detection of traces of leaks, it is necessary to immediately check the condition of the entire brake system as a whole.
Fuel hoses (every 30,000 km)
When servicing power system components, remember that gasoline is a highly flammable liquid. Do not smoke near the place of work, do not approach it with an open flame! Immediately collect all traces of spilled fuel, put rags soaked in fuel and lubricants in a place where the possibility of accidental ignition is absolutely excluded! Always keep a class B fire extinguisher handy! Try not to get gasoline on exposed skin - prolonged contact of this kind can lead to the development of cancer. Remember that the fuel injection system path is constantly under excessive internal pressure, which must be released without fail before starting work (see chapter Power supply systems, release and reduction of toxicity of exhaust gases).
Check all rubber fuel hoses for signs of material aging and other defects. Pay special attention to the condition of the kink areas and areas immediately in front of the ends put on the fittings.
Only high quality fuel hoses should be used as replacement lines. Under no circumstances should non-reinforced vacuum hoses, transparent plastic tubes or garden hoses be installed in the power system path. Usually, spring-type clamps are used to fix the fuel hoses on the fittings. These clamps lose their firmness over time, moreover, they often unexpectedly come off at the moment the hose is disconnected. It would be wise to replace this kind of clamps with more reliable and safe worm or screw clamps.
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